<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta charset="utf-8" /> <title>Built-in Functions — Python 3.7.4 documentation</title> <link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <script type="text/javascript" src="../_static/language_data.js"></script> <script type="text/javascript" src="../_static/sidebar.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python 3.7.4 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="index" title="Index" href="../genindex.html" /> <link rel="search" title="Search" href="../search.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="next" title="Built-in Constants" href="constants.html" /> <link rel="prev" title="Introduction" href="intro.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <link rel="canonical" href="https://docs.python.org/3/library/functions.html" /> <script type="text/javascript" src="../_static/copybutton.js"></script> <script type="text/javascript" src="../_static/switchers.js"></script> <style> @media only screen { table.full-width-table { width: 100%; } } </style> </head><body> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" accesskey="I">index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="constants.html" title="Built-in Constants" accesskey="N">next</a> |</li> <li class="right" > <a href="intro.html" title="Introduction" accesskey="P">previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <span class="language_switcher_placeholder">en</span> <span class="version_switcher_placeholder">3.7.4</span> <a href="../index.html">Documentation </a> » </li> <li class="nav-item nav-item-1"><a href="index.html" accesskey="U">The Python Standard Library</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="built-in-functions"> <span id="built-in-funcs"></span><h1>Built-in Functions<a class="headerlink" href="#built-in-functions" title="Permalink to this headline">¶</a></h1> <p>The Python interpreter has a number of functions and types built into it that are always available. They are listed here in alphabetical order.</p> <table class="docutils align-center"> <colgroup> <col style="width: 21%" /> <col style="width: 18%" /> <col style="width: 20%" /> <col style="width: 20%" /> <col style="width: 22%" /> </colgroup> <thead> <tr class="row-odd"><th class="head"></th> <th class="head"></th> <th class="head"><p>Built-in Functions</p></th> <th class="head"></th> <th class="head"></th> </tr> </thead> <tbody> <tr class="row-even"><td><p><a class="reference internal" href="#abs" title="abs"><code class="xref py py-func docutils literal notranslate"><span class="pre">abs()</span></code></a></p></td> <td><p><a class="reference internal" href="#delattr" title="delattr"><code class="xref py py-func docutils literal notranslate"><span class="pre">delattr()</span></code></a></p></td> <td><p><a class="reference internal" href="#hash" title="hash"><code class="xref py py-func docutils literal notranslate"><span class="pre">hash()</span></code></a></p></td> <td><p><a class="reference internal" href="#func-memoryview"><code class="docutils literal notranslate"><span class="pre">memoryview()</span></code></a></p></td> <td><p><a class="reference internal" href="#func-set"><code class="docutils literal notranslate"><span class="pre">set()</span></code></a></p></td> </tr> <tr class="row-odd"><td><p><a class="reference internal" href="#all" title="all"><code class="xref py py-func docutils literal notranslate"><span class="pre">all()</span></code></a></p></td> <td><p><a class="reference internal" href="#func-dict"><code class="docutils literal notranslate"><span class="pre">dict()</span></code></a></p></td> <td><p><a class="reference internal" href="#help" title="help"><code class="xref py py-func docutils literal notranslate"><span class="pre">help()</span></code></a></p></td> <td><p><a class="reference internal" href="#min" title="min"><code class="xref py py-func docutils literal notranslate"><span class="pre">min()</span></code></a></p></td> <td><p><a class="reference internal" href="#setattr" title="setattr"><code class="xref py py-func docutils literal notranslate"><span class="pre">setattr()</span></code></a></p></td> </tr> <tr class="row-even"><td><p><a class="reference internal" href="#any" title="any"><code class="xref py py-func docutils literal notranslate"><span class="pre">any()</span></code></a></p></td> <td><p><a class="reference internal" href="#dir" title="dir"><code class="xref py py-func docutils literal notranslate"><span class="pre">dir()</span></code></a></p></td> <td><p><a class="reference internal" href="#hex" title="hex"><code class="xref py py-func docutils literal notranslate"><span class="pre">hex()</span></code></a></p></td> <td><p><a class="reference internal" href="#next" title="next"><code class="xref py py-func docutils literal notranslate"><span class="pre">next()</span></code></a></p></td> <td><p><a class="reference internal" href="#slice" title="slice"><code class="xref py py-func docutils literal notranslate"><span class="pre">slice()</span></code></a></p></td> </tr> <tr class="row-odd"><td><p><a class="reference internal" href="#ascii" title="ascii"><code class="xref py py-func docutils literal notranslate"><span class="pre">ascii()</span></code></a></p></td> <td><p><a class="reference internal" href="#divmod" title="divmod"><code class="xref py py-func docutils literal notranslate"><span class="pre">divmod()</span></code></a></p></td> <td><p><a class="reference internal" href="#id" title="id"><code class="xref py py-func docutils literal notranslate"><span class="pre">id()</span></code></a></p></td> <td><p><a class="reference internal" href="#object" title="object"><code class="xref py py-func docutils literal notranslate"><span class="pre">object()</span></code></a></p></td> <td><p><a class="reference internal" href="#sorted" title="sorted"><code class="xref py py-func docutils literal notranslate"><span class="pre">sorted()</span></code></a></p></td> </tr> <tr class="row-even"><td><p><a class="reference internal" href="#bin" title="bin"><code class="xref py py-func docutils literal notranslate"><span class="pre">bin()</span></code></a></p></td> <td><p><a class="reference internal" href="#enumerate" title="enumerate"><code class="xref py py-func docutils literal notranslate"><span class="pre">enumerate()</span></code></a></p></td> <td><p><a class="reference internal" href="#input" title="input"><code class="xref py py-func docutils literal notranslate"><span class="pre">input()</span></code></a></p></td> <td><p><a class="reference internal" href="#oct" title="oct"><code class="xref py py-func docutils literal notranslate"><span class="pre">oct()</span></code></a></p></td> <td><p><a class="reference internal" href="#staticmethod" title="staticmethod"><code class="xref py py-func docutils literal notranslate"><span class="pre">staticmethod()</span></code></a></p></td> </tr> <tr class="row-odd"><td><p><a class="reference internal" href="#bool" title="bool"><code class="xref py py-func docutils literal notranslate"><span class="pre">bool()</span></code></a></p></td> <td><p><a class="reference internal" href="#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a></p></td> <td><p><a class="reference internal" href="#int" title="int"><code class="xref py py-func docutils literal notranslate"><span class="pre">int()</span></code></a></p></td> <td><p><a class="reference internal" href="#open" title="open"><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code></a></p></td> <td><p><a class="reference internal" href="#func-str"><code class="docutils literal notranslate"><span class="pre">str()</span></code></a></p></td> </tr> <tr class="row-even"><td><p><a class="reference internal" href="#breakpoint" title="breakpoint"><code class="xref py py-func docutils literal notranslate"><span class="pre">breakpoint()</span></code></a></p></td> <td><p><a class="reference internal" href="#exec" title="exec"><code class="xref py py-func docutils literal notranslate"><span class="pre">exec()</span></code></a></p></td> <td><p><a class="reference internal" href="#isinstance" title="isinstance"><code class="xref py py-func docutils literal notranslate"><span class="pre">isinstance()</span></code></a></p></td> <td><p><a class="reference internal" href="#ord" title="ord"><code class="xref py py-func docutils literal notranslate"><span class="pre">ord()</span></code></a></p></td> <td><p><a class="reference internal" href="#sum" title="sum"><code class="xref py py-func docutils literal notranslate"><span class="pre">sum()</span></code></a></p></td> </tr> <tr class="row-odd"><td><p><a class="reference internal" href="#func-bytearray"><code class="docutils literal notranslate"><span class="pre">bytearray()</span></code></a></p></td> <td><p><a class="reference internal" href="#filter" title="filter"><code class="xref py py-func docutils literal notranslate"><span class="pre">filter()</span></code></a></p></td> <td><p><a class="reference internal" href="#issubclass" title="issubclass"><code class="xref py py-func docutils literal notranslate"><span class="pre">issubclass()</span></code></a></p></td> <td><p><a class="reference internal" href="#pow" title="pow"><code class="xref py py-func docutils literal notranslate"><span class="pre">pow()</span></code></a></p></td> <td><p><a class="reference internal" href="#super" title="super"><code class="xref py py-func docutils literal notranslate"><span class="pre">super()</span></code></a></p></td> </tr> <tr class="row-even"><td><p><a class="reference internal" href="#func-bytes"><code class="docutils literal notranslate"><span class="pre">bytes()</span></code></a></p></td> <td><p><a class="reference internal" href="#float" title="float"><code class="xref py py-func docutils literal notranslate"><span class="pre">float()</span></code></a></p></td> <td><p><a class="reference internal" href="#iter" title="iter"><code class="xref py py-func docutils literal notranslate"><span class="pre">iter()</span></code></a></p></td> <td><p><a class="reference internal" href="#print" title="print"><code class="xref py py-func docutils literal notranslate"><span class="pre">print()</span></code></a></p></td> <td><p><a class="reference internal" href="#func-tuple"><code class="docutils literal notranslate"><span class="pre">tuple()</span></code></a></p></td> </tr> <tr class="row-odd"><td><p><a class="reference internal" href="#callable" title="callable"><code class="xref py py-func docutils literal notranslate"><span class="pre">callable()</span></code></a></p></td> <td><p><a class="reference internal" href="#format" title="format"><code class="xref py py-func docutils literal notranslate"><span class="pre">format()</span></code></a></p></td> <td><p><a class="reference internal" href="#len" title="len"><code class="xref py py-func docutils literal notranslate"><span class="pre">len()</span></code></a></p></td> <td><p><a class="reference internal" href="#property" title="property"><code class="xref py py-func docutils literal notranslate"><span class="pre">property()</span></code></a></p></td> <td><p><a class="reference internal" href="#type" title="type"><code class="xref py py-func docutils literal notranslate"><span class="pre">type()</span></code></a></p></td> </tr> <tr class="row-even"><td><p><a class="reference internal" href="#chr" title="chr"><code class="xref py py-func docutils literal notranslate"><span class="pre">chr()</span></code></a></p></td> <td><p><a class="reference internal" href="#func-frozenset"><code class="docutils literal notranslate"><span class="pre">frozenset()</span></code></a></p></td> <td><p><a class="reference internal" href="#func-list"><code class="docutils literal notranslate"><span class="pre">list()</span></code></a></p></td> <td><p><a class="reference internal" href="#func-range"><code class="docutils literal notranslate"><span class="pre">range()</span></code></a></p></td> <td><p><a class="reference internal" href="#vars" title="vars"><code class="xref py py-func docutils literal notranslate"><span class="pre">vars()</span></code></a></p></td> </tr> <tr class="row-odd"><td><p><a class="reference internal" href="#classmethod" title="classmethod"><code class="xref py py-func docutils literal notranslate"><span class="pre">classmethod()</span></code></a></p></td> <td><p><a class="reference internal" href="#getattr" title="getattr"><code class="xref py py-func docutils literal notranslate"><span class="pre">getattr()</span></code></a></p></td> <td><p><a class="reference internal" href="#locals" title="locals"><code class="xref py py-func docutils literal notranslate"><span class="pre">locals()</span></code></a></p></td> <td><p><a class="reference internal" href="#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a></p></td> <td><p><a class="reference internal" href="#zip" title="zip"><code class="xref py py-func docutils literal notranslate"><span class="pre">zip()</span></code></a></p></td> </tr> <tr class="row-even"><td><p><a class="reference internal" href="#compile" title="compile"><code class="xref py py-func docutils literal notranslate"><span class="pre">compile()</span></code></a></p></td> <td><p><a class="reference internal" href="#globals" title="globals"><code class="xref py py-func docutils literal notranslate"><span class="pre">globals()</span></code></a></p></td> <td><p><a class="reference internal" href="#map" title="map"><code class="xref py py-func docutils literal notranslate"><span class="pre">map()</span></code></a></p></td> <td><p><a class="reference internal" href="#reversed" title="reversed"><code class="xref py py-func docutils literal notranslate"><span class="pre">reversed()</span></code></a></p></td> <td><p><a class="reference internal" href="#__import__" title="__import__"><code class="xref py py-func docutils literal notranslate"><span class="pre">__import__()</span></code></a></p></td> </tr> <tr class="row-odd"><td><p><a class="reference internal" href="#complex" title="complex"><code class="xref py py-func docutils literal notranslate"><span class="pre">complex()</span></code></a></p></td> <td><p><a class="reference internal" href="#hasattr" title="hasattr"><code class="xref py py-func docutils literal notranslate"><span class="pre">hasattr()</span></code></a></p></td> <td><p><a class="reference internal" href="#max" title="max"><code class="xref py py-func docutils literal notranslate"><span class="pre">max()</span></code></a></p></td> <td><p><a class="reference internal" href="#round" title="round"><code class="xref py py-func docutils literal notranslate"><span class="pre">round()</span></code></a></p></td> <td></td> </tr> </tbody> </table> <dl class="function"> <dt id="abs"> <code class="descname">abs</code><span class="sig-paren">(</span><em>x</em><span class="sig-paren">)</span><a class="headerlink" href="#abs" title="Permalink to this definition">¶</a></dt> <dd><p>Return the absolute value of a number. The argument may be an integer or a floating point number. If the argument is a complex number, its magnitude is returned.</p> </dd></dl> <dl class="function"> <dt id="all"> <code class="descname">all</code><span class="sig-paren">(</span><em>iterable</em><span class="sig-paren">)</span><a class="headerlink" href="#all" title="Permalink to this definition">¶</a></dt> <dd><p>Return <code class="docutils literal notranslate"><span class="pre">True</span></code> if all elements of the <em>iterable</em> are true (or if the iterable is empty). Equivalent to:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">all</span><span class="p">(</span><span class="n">iterable</span><span class="p">):</span> <span class="k">for</span> <span class="n">element</span> <span class="ow">in</span> <span class="n">iterable</span><span class="p">:</span> <span class="k">if</span> <span class="ow">not</span> <span class="n">element</span><span class="p">:</span> <span class="k">return</span> <span class="kc">False</span> <span class="k">return</span> <span class="kc">True</span> </pre></div> </div> </dd></dl> <dl class="function"> <dt id="any"> <code class="descname">any</code><span class="sig-paren">(</span><em>iterable</em><span class="sig-paren">)</span><a class="headerlink" href="#any" title="Permalink to this definition">¶</a></dt> <dd><p>Return <code class="docutils literal notranslate"><span class="pre">True</span></code> if any element of the <em>iterable</em> is true. If the iterable is empty, return <code class="docutils literal notranslate"><span class="pre">False</span></code>. Equivalent to:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">any</span><span class="p">(</span><span class="n">iterable</span><span class="p">):</span> <span class="k">for</span> <span class="n">element</span> <span class="ow">in</span> <span class="n">iterable</span><span class="p">:</span> <span class="k">if</span> <span class="n">element</span><span class="p">:</span> <span class="k">return</span> <span class="kc">True</span> <span class="k">return</span> <span class="kc">False</span> </pre></div> </div> </dd></dl> <dl class="function"> <dt id="ascii"> <code class="descname">ascii</code><span class="sig-paren">(</span><em>object</em><span class="sig-paren">)</span><a class="headerlink" href="#ascii" title="Permalink to this definition">¶</a></dt> <dd><p>As <a class="reference internal" href="#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a>, return a string containing a printable representation of an object, but escape the non-ASCII characters in the string returned by <a class="reference internal" href="#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a> using <code class="docutils literal notranslate"><span class="pre">\x</span></code>, <code class="docutils literal notranslate"><span class="pre">\u</span></code> or <code class="docutils literal notranslate"><span class="pre">\U</span></code> escapes. This generates a string similar to that returned by <a class="reference internal" href="#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a> in Python 2.</p> </dd></dl> <dl class="function"> <dt id="bin"> <code class="descname">bin</code><span class="sig-paren">(</span><em>x</em><span class="sig-paren">)</span><a class="headerlink" href="#bin" title="Permalink to this definition">¶</a></dt> <dd><p>Convert an integer number to a binary string prefixed with “0b”. The result is a valid Python expression. If <em>x</em> is not a Python <a class="reference internal" href="#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a> object, it has to define an <a class="reference internal" href="../reference/datamodel.html#object.__index__" title="object.__index__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__index__()</span></code></a> method that returns an integer. Some examples:</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">bin</span><span class="p">(</span><span class="mi">3</span><span class="p">)</span> <span class="go">'0b11'</span> <span class="gp">>>> </span><span class="nb">bin</span><span class="p">(</span><span class="o">-</span><span class="mi">10</span><span class="p">)</span> <span class="go">'-0b1010'</span> </pre></div> </div> <p>If prefix “0b” is desired or not, you can use either of the following ways.</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">format</span><span class="p">(</span><span class="mi">14</span><span class="p">,</span> <span class="s1">'#b'</span><span class="p">),</span> <span class="nb">format</span><span class="p">(</span><span class="mi">14</span><span class="p">,</span> <span class="s1">'b'</span><span class="p">)</span> <span class="go">('0b1110', '1110')</span> <span class="gp">>>> </span><span class="n">f</span><span class="s1">'</span><span class="si">{14:#b}</span><span class="s1">'</span><span class="p">,</span> <span class="n">f</span><span class="s1">'</span><span class="si">{14:b}</span><span class="s1">'</span> <span class="go">('0b1110', '1110')</span> </pre></div> </div> <p>See also <a class="reference internal" href="#format" title="format"><code class="xref py py-func docutils literal notranslate"><span class="pre">format()</span></code></a> for more information.</p> </dd></dl> <dl class="class"> <dt id="bool"> <em class="property">class </em><code class="descname">bool</code><span class="sig-paren">(</span><span class="optional">[</span><em>x</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#bool" title="Permalink to this definition">¶</a></dt> <dd><p>Return a Boolean value, i.e. one of <code class="docutils literal notranslate"><span class="pre">True</span></code> or <code class="docutils literal notranslate"><span class="pre">False</span></code>. <em>x</em> is converted using the standard <a class="reference internal" href="stdtypes.html#truth"><span class="std std-ref">truth testing procedure</span></a>. If <em>x</em> is false or omitted, this returns <code class="docutils literal notranslate"><span class="pre">False</span></code>; otherwise it returns <code class="docutils literal notranslate"><span class="pre">True</span></code>. The <a class="reference internal" href="#bool" title="bool"><code class="xref py py-class docutils literal notranslate"><span class="pre">bool</span></code></a> class is a subclass of <a class="reference internal" href="#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a> (see <a class="reference internal" href="stdtypes.html#typesnumeric"><span class="std std-ref">Numeric Types — int, float, complex</span></a>). It cannot be subclassed further. Its only instances are <code class="docutils literal notranslate"><span class="pre">False</span></code> and <code class="docutils literal notranslate"><span class="pre">True</span></code> (see <a class="reference internal" href="stdtypes.html#bltin-boolean-values"><span class="std std-ref">Boolean Values</span></a>).</p> <div class="versionchanged" id="index-0"> <p><span class="versionmodified changed">Changed in version 3.7: </span><em>x</em> is now a positional-only parameter.</p> </div> </dd></dl> <dl class="function"> <dt id="breakpoint"> <code class="descname">breakpoint</code><span class="sig-paren">(</span><em>*args</em>, <em>**kws</em><span class="sig-paren">)</span><a class="headerlink" href="#breakpoint" title="Permalink to this definition">¶</a></dt> <dd><p>This function drops you into the debugger at the call site. Specifically, it calls <a class="reference internal" href="sys.html#sys.breakpointhook" title="sys.breakpointhook"><code class="xref py py-func docutils literal notranslate"><span class="pre">sys.breakpointhook()</span></code></a>, passing <code class="docutils literal notranslate"><span class="pre">args</span></code> and <code class="docutils literal notranslate"><span class="pre">kws</span></code> straight through. By default, <code class="docutils literal notranslate"><span class="pre">sys.breakpointhook()</span></code> calls <a class="reference internal" href="pdb.html#pdb.set_trace" title="pdb.set_trace"><code class="xref py py-func docutils literal notranslate"><span class="pre">pdb.set_trace()</span></code></a> expecting no arguments. In this case, it is purely a convenience function so you don’t have to explicitly import <a class="reference internal" href="pdb.html#module-pdb" title="pdb: The Python debugger for interactive interpreters."><code class="xref py py-mod docutils literal notranslate"><span class="pre">pdb</span></code></a> or type as much code to enter the debugger. However, <a class="reference internal" href="sys.html#sys.breakpointhook" title="sys.breakpointhook"><code class="xref py py-func docutils literal notranslate"><span class="pre">sys.breakpointhook()</span></code></a> can be set to some other function and <a class="reference internal" href="#breakpoint" title="breakpoint"><code class="xref py py-func docutils literal notranslate"><span class="pre">breakpoint()</span></code></a> will automatically call that, allowing you to drop into the debugger of choice.</p> <div class="versionadded"> <p><span class="versionmodified added">New in version 3.7.</span></p> </div> </dd></dl> <span class="target" id="func-bytearray"></span><dl class="class"> <dt> <em class="property">class </em><code class="descname">bytearray</code><span class="sig-paren">(</span><span class="optional">[</span><em>source</em><span class="optional">[</span>, <em>encoding</em><span class="optional">[</span>, <em>errors</em><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span></dt> <dd><p>Return a new array of bytes. The <a class="reference internal" href="stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a> class is a mutable sequence of integers in the range 0 <= x < 256. It has most of the usual methods of mutable sequences, described in <a class="reference internal" href="stdtypes.html#typesseq-mutable"><span class="std std-ref">Mutable Sequence Types</span></a>, as well as most methods that the <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> type has, see <a class="reference internal" href="stdtypes.html#bytes-methods"><span class="std std-ref">Bytes and Bytearray Operations</span></a>.</p> <p>The optional <em>source</em> parameter can be used to initialize the array in a few different ways:</p> <ul class="simple"> <li><p>If it is a <em>string</em>, you must also give the <em>encoding</em> (and optionally, <em>errors</em>) parameters; <a class="reference internal" href="stdtypes.html#bytearray" title="bytearray"><code class="xref py py-func docutils literal notranslate"><span class="pre">bytearray()</span></code></a> then converts the string to bytes using <a class="reference internal" href="stdtypes.html#str.encode" title="str.encode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">str.encode()</span></code></a>.</p></li> <li><p>If it is an <em>integer</em>, the array will have that size and will be initialized with null bytes.</p></li> <li><p>If it is an object conforming to the <em>buffer</em> interface, a read-only buffer of the object will be used to initialize the bytes array.</p></li> <li><p>If it is an <em>iterable</em>, it must be an iterable of integers in the range <code class="docutils literal notranslate"><span class="pre">0</span> <span class="pre"><=</span> <span class="pre">x</span> <span class="pre"><</span> <span class="pre">256</span></code>, which are used as the initial contents of the array.</p></li> </ul> <p>Without an argument, an array of size 0 is created.</p> <p>See also <a class="reference internal" href="stdtypes.html#binaryseq"><span class="std std-ref">Binary Sequence Types — bytes, bytearray, memoryview</span></a> and <a class="reference internal" href="stdtypes.html#typebytearray"><span class="std std-ref">Bytearray Objects</span></a>.</p> </dd></dl> <span class="target" id="func-bytes"></span><dl class="class"> <dt> <em class="property">class </em><code class="descname">bytes</code><span class="sig-paren">(</span><span class="optional">[</span><em>source</em><span class="optional">[</span>, <em>encoding</em><span class="optional">[</span>, <em>errors</em><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span></dt> <dd><p>Return a new “bytes” object, which is an immutable sequence of integers in the range <code class="docutils literal notranslate"><span class="pre">0</span> <span class="pre"><=</span> <span class="pre">x</span> <span class="pre"><</span> <span class="pre">256</span></code>. <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> is an immutable version of <a class="reference internal" href="stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a> – it has the same non-mutating methods and the same indexing and slicing behavior.</p> <p>Accordingly, constructor arguments are interpreted as for <a class="reference internal" href="stdtypes.html#bytearray" title="bytearray"><code class="xref py py-func docutils literal notranslate"><span class="pre">bytearray()</span></code></a>.</p> <p>Bytes objects can also be created with literals, see <a class="reference internal" href="../reference/lexical_analysis.html#strings"><span class="std std-ref">String and Bytes literals</span></a>.</p> <p>See also <a class="reference internal" href="stdtypes.html#binaryseq"><span class="std std-ref">Binary Sequence Types — bytes, bytearray, memoryview</span></a>, <a class="reference internal" href="stdtypes.html#typebytes"><span class="std std-ref">Bytes Objects</span></a>, and <a class="reference internal" href="stdtypes.html#bytes-methods"><span class="std std-ref">Bytes and Bytearray Operations</span></a>.</p> </dd></dl> <dl class="function"> <dt id="callable"> <code class="descname">callable</code><span class="sig-paren">(</span><em>object</em><span class="sig-paren">)</span><a class="headerlink" href="#callable" title="Permalink to this definition">¶</a></dt> <dd><p>Return <a class="reference internal" href="constants.html#True" title="True"><code class="xref py py-const docutils literal notranslate"><span class="pre">True</span></code></a> if the <em>object</em> argument appears callable, <a class="reference internal" href="constants.html#False" title="False"><code class="xref py py-const docutils literal notranslate"><span class="pre">False</span></code></a> if not. If this returns true, it is still possible that a call fails, but if it is false, calling <em>object</em> will never succeed. Note that classes are callable (calling a class returns a new instance); instances are callable if their class has a <a class="reference internal" href="../reference/datamodel.html#object.__call__" title="object.__call__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__call__()</span></code></a> method.</p> <div class="versionadded"> <p><span class="versionmodified added">New in version 3.2: </span>This function was first removed in Python 3.0 and then brought back in Python 3.2.</p> </div> </dd></dl> <dl class="function"> <dt id="chr"> <code class="descname">chr</code><span class="sig-paren">(</span><em>i</em><span class="sig-paren">)</span><a class="headerlink" href="#chr" title="Permalink to this definition">¶</a></dt> <dd><p>Return the string representing a character whose Unicode code point is the integer <em>i</em>. For example, <code class="docutils literal notranslate"><span class="pre">chr(97)</span></code> returns the string <code class="docutils literal notranslate"><span class="pre">'a'</span></code>, while <code class="docutils literal notranslate"><span class="pre">chr(8364)</span></code> returns the string <code class="docutils literal notranslate"><span class="pre">'€'</span></code>. This is the inverse of <a class="reference internal" href="#ord" title="ord"><code class="xref py py-func docutils literal notranslate"><span class="pre">ord()</span></code></a>.</p> <p>The valid range for the argument is from 0 through 1,114,111 (0x10FFFF in base 16). <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> will be raised if <em>i</em> is outside that range.</p> </dd></dl> <dl class="function"> <dt id="classmethod"> <code class="descclassname">@</code><code class="descname">classmethod</code><a class="headerlink" href="#classmethod" title="Permalink to this definition">¶</a></dt> <dd><p>Transform a method into a class method.</p> <p>A class method receives the class as implicit first argument, just like an instance method receives the instance. To declare a class method, use this idiom:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">C</span><span class="p">:</span> <span class="nd">@classmethod</span> <span class="k">def</span> <span class="nf">f</span><span class="p">(</span><span class="bp">cls</span><span class="p">,</span> <span class="n">arg1</span><span class="p">,</span> <span class="n">arg2</span><span class="p">,</span> <span class="o">...</span><span class="p">):</span> <span class="o">...</span> </pre></div> </div> <p>The <code class="docutils literal notranslate"><span class="pre">@classmethod</span></code> form is a function <a class="reference internal" href="../glossary.html#term-decorator"><span class="xref std std-term">decorator</span></a> – see <a class="reference internal" href="../reference/compound_stmts.html#function"><span class="std std-ref">Function definitions</span></a> for details.</p> <p>A class method can be called either on the class (such as <code class="docutils literal notranslate"><span class="pre">C.f()</span></code>) or on an instance (such as <code class="docutils literal notranslate"><span class="pre">C().f()</span></code>). The instance is ignored except for its class. If a class method is called for a derived class, the derived class object is passed as the implied first argument.</p> <p>Class methods are different than C++ or Java static methods. If you want those, see <a class="reference internal" href="#staticmethod" title="staticmethod"><code class="xref py py-func docutils literal notranslate"><span class="pre">staticmethod()</span></code></a>.</p> <p>For more information on class methods, see <a class="reference internal" href="../reference/datamodel.html#types"><span class="std std-ref">The standard type hierarchy</span></a>.</p> </dd></dl> <dl class="function"> <dt id="compile"> <code class="descname">compile</code><span class="sig-paren">(</span><em>source</em>, <em>filename</em>, <em>mode</em>, <em>flags=0</em>, <em>dont_inherit=False</em>, <em>optimize=-1</em><span class="sig-paren">)</span><a class="headerlink" href="#compile" title="Permalink to this definition">¶</a></dt> <dd><p>Compile the <em>source</em> into a code or AST object. Code objects can be executed by <a class="reference internal" href="#exec" title="exec"><code class="xref py py-func docutils literal notranslate"><span class="pre">exec()</span></code></a> or <a class="reference internal" href="#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a>. <em>source</em> can either be a normal string, a byte string, or an AST object. Refer to the <a class="reference internal" href="ast.html#module-ast" title="ast: Abstract Syntax Tree classes and manipulation."><code class="xref py py-mod docutils literal notranslate"><span class="pre">ast</span></code></a> module documentation for information on how to work with AST objects.</p> <p>The <em>filename</em> argument should give the file from which the code was read; pass some recognizable value if it wasn’t read from a file (<code class="docutils literal notranslate"><span class="pre">'<string>'</span></code> is commonly used).</p> <p>The <em>mode</em> argument specifies what kind of code must be compiled; it can be <code class="docutils literal notranslate"><span class="pre">'exec'</span></code> if <em>source</em> consists of a sequence of statements, <code class="docutils literal notranslate"><span class="pre">'eval'</span></code> if it consists of a single expression, or <code class="docutils literal notranslate"><span class="pre">'single'</span></code> if it consists of a single interactive statement (in the latter case, expression statements that evaluate to something other than <code class="docutils literal notranslate"><span class="pre">None</span></code> will be printed).</p> <p>The optional arguments <em>flags</em> and <em>dont_inherit</em> control which <a class="reference internal" href="../reference/simple_stmts.html#future"><span class="std std-ref">future statements</span></a> affect the compilation of <em>source</em>. If neither is present (or both are zero) the code is compiled with those future statements that are in effect in the code that is calling <a class="reference internal" href="#compile" title="compile"><code class="xref py py-func docutils literal notranslate"><span class="pre">compile()</span></code></a>. If the <em>flags</em> argument is given and <em>dont_inherit</em> is not (or is zero) then the future statements specified by the <em>flags</em> argument are used in addition to those that would be used anyway. If <em>dont_inherit</em> is a non-zero integer then the <em>flags</em> argument is it – the future statements in effect around the call to compile are ignored.</p> <p>Future statements are specified by bits which can be bitwise ORed together to specify multiple statements. The bitfield required to specify a given feature can be found as the <code class="xref py py-attr docutils literal notranslate"><span class="pre">compiler_flag</span></code> attribute on the <code class="xref py py-class docutils literal notranslate"><span class="pre">_Feature</span></code> instance in the <a class="reference internal" href="__future__.html#module-__future__" title="__future__: Future statement definitions"><code class="xref py py-mod docutils literal notranslate"><span class="pre">__future__</span></code></a> module.</p> <p>The argument <em>optimize</em> specifies the optimization level of the compiler; the default value of <code class="docutils literal notranslate"><span class="pre">-1</span></code> selects the optimization level of the interpreter as given by <a class="reference internal" href="../using/cmdline.html#cmdoption-o"><code class="xref std std-option docutils literal notranslate"><span class="pre">-O</span></code></a> options. Explicit levels are <code class="docutils literal notranslate"><span class="pre">0</span></code> (no optimization; <code class="docutils literal notranslate"><span class="pre">__debug__</span></code> is true), <code class="docutils literal notranslate"><span class="pre">1</span></code> (asserts are removed, <code class="docutils literal notranslate"><span class="pre">__debug__</span></code> is false) or <code class="docutils literal notranslate"><span class="pre">2</span></code> (docstrings are removed too).</p> <p>This function raises <a class="reference internal" href="exceptions.html#SyntaxError" title="SyntaxError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SyntaxError</span></code></a> if the compiled source is invalid, and <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> if the source contains null bytes.</p> <p>If you want to parse Python code into its AST representation, see <a class="reference internal" href="ast.html#ast.parse" title="ast.parse"><code class="xref py py-func docutils literal notranslate"><span class="pre">ast.parse()</span></code></a>.</p> <div class="admonition note"> <p class="admonition-title">Note</p> <p>When compiling a string with multi-line code in <code class="docutils literal notranslate"><span class="pre">'single'</span></code> or <code class="docutils literal notranslate"><span class="pre">'eval'</span></code> mode, input must be terminated by at least one newline character. This is to facilitate detection of incomplete and complete statements in the <a class="reference internal" href="code.html#module-code" title="code: Facilities to implement read-eval-print loops."><code class="xref py py-mod docutils literal notranslate"><span class="pre">code</span></code></a> module.</p> </div> <div class="admonition warning"> <p class="admonition-title">Warning</p> <p>It is possible to crash the Python interpreter with a sufficiently large/complex string when compiling to an AST object due to stack depth limitations in Python’s AST compiler.</p> </div> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.2: </span>Allowed use of Windows and Mac newlines. Also input in <code class="docutils literal notranslate"><span class="pre">'exec'</span></code> mode does not have to end in a newline anymore. Added the <em>optimize</em> parameter.</p> </div> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.5: </span>Previously, <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> was raised when null bytes were encountered in <em>source</em>.</p> </div> </dd></dl> <dl class="class"> <dt id="complex"> <em class="property">class </em><code class="descname">complex</code><span class="sig-paren">(</span><span class="optional">[</span><em>real</em><span class="optional">[</span>, <em>imag</em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#complex" title="Permalink to this definition">¶</a></dt> <dd><p>Return a complex number with the value <em>real</em> + <em>imag</em>*1j or convert a string or number to a complex number. If the first parameter is a string, it will be interpreted as a complex number and the function must be called without a second parameter. The second parameter can never be a string. Each argument may be any numeric type (including complex). If <em>imag</em> is omitted, it defaults to zero and the constructor serves as a numeric conversion like <a class="reference internal" href="#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a> and <a class="reference internal" href="#float" title="float"><code class="xref py py-class docutils literal notranslate"><span class="pre">float</span></code></a>. If both arguments are omitted, returns <code class="docutils literal notranslate"><span class="pre">0j</span></code>.</p> <div class="admonition note"> <p class="admonition-title">Note</p> <p>When converting from a string, the string must not contain whitespace around the central <code class="docutils literal notranslate"><span class="pre">+</span></code> or <code class="docutils literal notranslate"><span class="pre">-</span></code> operator. For example, <code class="docutils literal notranslate"><span class="pre">complex('1+2j')</span></code> is fine, but <code class="docutils literal notranslate"><span class="pre">complex('1</span> <span class="pre">+</span> <span class="pre">2j')</span></code> raises <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a>.</p> </div> <p>The complex type is described in <a class="reference internal" href="stdtypes.html#typesnumeric"><span class="std std-ref">Numeric Types — int, float, complex</span></a>.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.6: </span>Grouping digits with underscores as in code literals is allowed.</p> </div> </dd></dl> <dl class="function"> <dt id="delattr"> <code class="descname">delattr</code><span class="sig-paren">(</span><em>object</em>, <em>name</em><span class="sig-paren">)</span><a class="headerlink" href="#delattr" title="Permalink to this definition">¶</a></dt> <dd><p>This is a relative of <a class="reference internal" href="#setattr" title="setattr"><code class="xref py py-func docutils literal notranslate"><span class="pre">setattr()</span></code></a>. The arguments are an object and a string. The string must be the name of one of the object’s attributes. The function deletes the named attribute, provided the object allows it. For example, <code class="docutils literal notranslate"><span class="pre">delattr(x,</span> <span class="pre">'foobar')</span></code> is equivalent to <code class="docutils literal notranslate"><span class="pre">del</span> <span class="pre">x.foobar</span></code>.</p> </dd></dl> <span class="target" id="func-dict"></span><dl class="class"> <dt> <em class="property">class </em><code class="descname">dict</code><span class="sig-paren">(</span><em>**kwarg</em><span class="sig-paren">)</span></dt> <dt> <em class="property">class </em><code class="descname">dict</code><span class="sig-paren">(</span><em>mapping</em>, <em>**kwarg</em><span class="sig-paren">)</span></dt> <dt> <em class="property">class </em><code class="descname">dict</code><span class="sig-paren">(</span><em>iterable</em>, <em>**kwarg</em><span class="sig-paren">)</span></dt> <dd><p>Create a new dictionary. The <a class="reference internal" href="stdtypes.html#dict" title="dict"><code class="xref py py-class docutils literal notranslate"><span class="pre">dict</span></code></a> object is the dictionary class. See <a class="reference internal" href="stdtypes.html#dict" title="dict"><code class="xref py py-class docutils literal notranslate"><span class="pre">dict</span></code></a> and <a class="reference internal" href="stdtypes.html#typesmapping"><span class="std std-ref">Mapping Types — dict</span></a> for documentation about this class.</p> <p>For other containers see the built-in <a class="reference internal" href="stdtypes.html#list" title="list"><code class="xref py py-class docutils literal notranslate"><span class="pre">list</span></code></a>, <a class="reference internal" href="stdtypes.html#set" title="set"><code class="xref py py-class docutils literal notranslate"><span class="pre">set</span></code></a>, and <a class="reference internal" href="stdtypes.html#tuple" title="tuple"><code class="xref py py-class docutils literal notranslate"><span class="pre">tuple</span></code></a> classes, as well as the <a class="reference internal" href="collections.html#module-collections" title="collections: Container datatypes"><code class="xref py py-mod docutils literal notranslate"><span class="pre">collections</span></code></a> module.</p> </dd></dl> <dl class="function"> <dt id="dir"> <code class="descname">dir</code><span class="sig-paren">(</span><span class="optional">[</span><em>object</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#dir" title="Permalink to this definition">¶</a></dt> <dd><p>Without arguments, return the list of names in the current local scope. With an argument, attempt to return a list of valid attributes for that object.</p> <p>If the object has a method named <a class="reference internal" href="../reference/datamodel.html#object.__dir__" title="object.__dir__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__dir__()</span></code></a>, this method will be called and must return the list of attributes. This allows objects that implement a custom <a class="reference internal" href="../reference/datamodel.html#object.__getattr__" title="object.__getattr__"><code class="xref py py-func docutils literal notranslate"><span class="pre">__getattr__()</span></code></a> or <a class="reference internal" href="../reference/datamodel.html#object.__getattribute__" title="object.__getattribute__"><code class="xref py py-func docutils literal notranslate"><span class="pre">__getattribute__()</span></code></a> function to customize the way <a class="reference internal" href="#dir" title="dir"><code class="xref py py-func docutils literal notranslate"><span class="pre">dir()</span></code></a> reports their attributes.</p> <p>If the object does not provide <a class="reference internal" href="../reference/datamodel.html#object.__dir__" title="object.__dir__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__dir__()</span></code></a>, the function tries its best to gather information from the object’s <a class="reference internal" href="stdtypes.html#object.__dict__" title="object.__dict__"><code class="xref py py-attr docutils literal notranslate"><span class="pre">__dict__</span></code></a> attribute, if defined, and from its type object. The resulting list is not necessarily complete, and may be inaccurate when the object has a custom <a class="reference internal" href="../reference/datamodel.html#object.__getattr__" title="object.__getattr__"><code class="xref py py-func docutils literal notranslate"><span class="pre">__getattr__()</span></code></a>.</p> <p>The default <a class="reference internal" href="#dir" title="dir"><code class="xref py py-func docutils literal notranslate"><span class="pre">dir()</span></code></a> mechanism behaves differently with different types of objects, as it attempts to produce the most relevant, rather than complete, information:</p> <ul class="simple"> <li><p>If the object is a module object, the list contains the names of the module’s attributes.</p></li> <li><p>If the object is a type or class object, the list contains the names of its attributes, and recursively of the attributes of its bases.</p></li> <li><p>Otherwise, the list contains the object’s attributes’ names, the names of its class’s attributes, and recursively of the attributes of its class’s base classes.</p></li> </ul> <p>The resulting list is sorted alphabetically. For example:</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">struct</span> <span class="gp">>>> </span><span class="nb">dir</span><span class="p">()</span> <span class="c1"># show the names in the module namespace # doctest: +SKIP</span> <span class="go">['__builtins__', '__name__', 'struct']</span> <span class="gp">>>> </span><span class="nb">dir</span><span class="p">(</span><span class="n">struct</span><span class="p">)</span> <span class="c1"># show the names in the struct module # doctest: +SKIP</span> <span class="go">['Struct', '__all__', '__builtins__', '__cached__', '__doc__', '__file__',</span> <span class="go"> '__initializing__', '__loader__', '__name__', '__package__',</span> <span class="go"> '_clearcache', 'calcsize', 'error', 'pack', 'pack_into',</span> <span class="go"> 'unpack', 'unpack_from']</span> <span class="gp">>>> </span><span class="k">class</span> <span class="nc">Shape</span><span class="p">:</span> <span class="gp">... </span> <span class="k">def</span> <span class="nf">__dir__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="gp">... </span> <span class="k">return</span> <span class="p">[</span><span class="s1">'area'</span><span class="p">,</span> <span class="s1">'perimeter'</span><span class="p">,</span> <span class="s1">'location'</span><span class="p">]</span> <span class="gp">>>> </span><span class="n">s</span> <span class="o">=</span> <span class="n">Shape</span><span class="p">()</span> <span class="gp">>>> </span><span class="nb">dir</span><span class="p">(</span><span class="n">s</span><span class="p">)</span> <span class="go">['area', 'location', 'perimeter']</span> </pre></div> </div> <div class="admonition note"> <p class="admonition-title">Note</p> <p>Because <a class="reference internal" href="#dir" title="dir"><code class="xref py py-func docutils literal notranslate"><span class="pre">dir()</span></code></a> is supplied primarily as a convenience for use at an interactive prompt, it tries to supply an interesting set of names more than it tries to supply a rigorously or consistently defined set of names, and its detailed behavior may change across releases. For example, metaclass attributes are not in the result list when the argument is a class.</p> </div> </dd></dl> <dl class="function"> <dt id="divmod"> <code class="descname">divmod</code><span class="sig-paren">(</span><em>a</em>, <em>b</em><span class="sig-paren">)</span><a class="headerlink" href="#divmod" title="Permalink to this definition">¶</a></dt> <dd><p>Take two (non complex) numbers as arguments and return a pair of numbers consisting of their quotient and remainder when using integer division. With mixed operand types, the rules for binary arithmetic operators apply. For integers, the result is the same as <code class="docutils literal notranslate"><span class="pre">(a</span> <span class="pre">//</span> <span class="pre">b,</span> <span class="pre">a</span> <span class="pre">%</span> <span class="pre">b)</span></code>. For floating point numbers the result is <code class="docutils literal notranslate"><span class="pre">(q,</span> <span class="pre">a</span> <span class="pre">%</span> <span class="pre">b)</span></code>, where <em>q</em> is usually <code class="docutils literal notranslate"><span class="pre">math.floor(a</span> <span class="pre">/</span> <span class="pre">b)</span></code> but may be 1 less than that. In any case <code class="docutils literal notranslate"><span class="pre">q</span> <span class="pre">*</span> <span class="pre">b</span> <span class="pre">+</span> <span class="pre">a</span> <span class="pre">%</span> <span class="pre">b</span></code> is very close to <em>a</em>, if <code class="docutils literal notranslate"><span class="pre">a</span> <span class="pre">%</span> <span class="pre">b</span></code> is non-zero it has the same sign as <em>b</em>, and <code class="docutils literal notranslate"><span class="pre">0</span> <span class="pre"><=</span> <span class="pre">abs(a</span> <span class="pre">%</span> <span class="pre">b)</span> <span class="pre"><</span> <span class="pre">abs(b)</span></code>.</p> </dd></dl> <dl class="function"> <dt id="enumerate"> <code class="descname">enumerate</code><span class="sig-paren">(</span><em>iterable</em>, <em>start=0</em><span class="sig-paren">)</span><a class="headerlink" href="#enumerate" title="Permalink to this definition">¶</a></dt> <dd><p>Return an enumerate object. <em>iterable</em> must be a sequence, an <a class="reference internal" href="../glossary.html#term-iterator"><span class="xref std std-term">iterator</span></a>, or some other object which supports iteration. The <a class="reference internal" href="stdtypes.html#iterator.__next__" title="iterator.__next__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__next__()</span></code></a> method of the iterator returned by <a class="reference internal" href="#enumerate" title="enumerate"><code class="xref py py-func docutils literal notranslate"><span class="pre">enumerate()</span></code></a> returns a tuple containing a count (from <em>start</em> which defaults to 0) and the values obtained from iterating over <em>iterable</em>.</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">seasons</span> <span class="o">=</span> <span class="p">[</span><span class="s1">'Spring'</span><span class="p">,</span> <span class="s1">'Summer'</span><span class="p">,</span> <span class="s1">'Fall'</span><span class="p">,</span> <span class="s1">'Winter'</span><span class="p">]</span> <span class="gp">>>> </span><span class="nb">list</span><span class="p">(</span><span class="nb">enumerate</span><span class="p">(</span><span class="n">seasons</span><span class="p">))</span> <span class="go">[(0, 'Spring'), (1, 'Summer'), (2, 'Fall'), (3, 'Winter')]</span> <span class="gp">>>> </span><span class="nb">list</span><span class="p">(</span><span class="nb">enumerate</span><span class="p">(</span><span class="n">seasons</span><span class="p">,</span> <span class="n">start</span><span class="o">=</span><span class="mi">1</span><span class="p">))</span> <span class="go">[(1, 'Spring'), (2, 'Summer'), (3, 'Fall'), (4, 'Winter')]</span> </pre></div> </div> <p>Equivalent to:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">enumerate</span><span class="p">(</span><span class="n">sequence</span><span class="p">,</span> <span class="n">start</span><span class="o">=</span><span class="mi">0</span><span class="p">):</span> <span class="n">n</span> <span class="o">=</span> <span class="n">start</span> <span class="k">for</span> <span class="n">elem</span> <span class="ow">in</span> <span class="n">sequence</span><span class="p">:</span> <span class="k">yield</span> <span class="n">n</span><span class="p">,</span> <span class="n">elem</span> <span class="n">n</span> <span class="o">+=</span> <span class="mi">1</span> </pre></div> </div> </dd></dl> <dl class="function"> <dt id="eval"> <code class="descname">eval</code><span class="sig-paren">(</span><em>expression</em>, <em>globals=None</em>, <em>locals=None</em><span class="sig-paren">)</span><a class="headerlink" href="#eval" title="Permalink to this definition">¶</a></dt> <dd><p>The arguments are a string and optional globals and locals. If provided, <em>globals</em> must be a dictionary. If provided, <em>locals</em> can be any mapping object.</p> <p>The <em>expression</em> argument is parsed and evaluated as a Python expression (technically speaking, a condition list) using the <em>globals</em> and <em>locals</em> dictionaries as global and local namespace. If the <em>globals</em> dictionary is present and does not contain a value for the key <code class="docutils literal notranslate"><span class="pre">__builtins__</span></code>, a reference to the dictionary of the built-in module <a class="reference internal" href="builtins.html#module-builtins" title="builtins: The module that provides the built-in namespace."><code class="xref py py-mod docutils literal notranslate"><span class="pre">builtins</span></code></a> is inserted under that key before <em>expression</em> is parsed. This means that <em>expression</em> normally has full access to the standard <a class="reference internal" href="builtins.html#module-builtins" title="builtins: The module that provides the built-in namespace."><code class="xref py py-mod docutils literal notranslate"><span class="pre">builtins</span></code></a> module and restricted environments are propagated. If the <em>locals</em> dictionary is omitted it defaults to the <em>globals</em> dictionary. If both dictionaries are omitted, the expression is executed in the environment where <a class="reference internal" href="#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a> is called. The return value is the result of the evaluated expression. Syntax errors are reported as exceptions. Example:</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">x</span> <span class="o">=</span> <span class="mi">1</span> <span class="gp">>>> </span><span class="nb">eval</span><span class="p">(</span><span class="s1">'x+1'</span><span class="p">)</span> <span class="go">2</span> </pre></div> </div> <p>This function can also be used to execute arbitrary code objects (such as those created by <a class="reference internal" href="#compile" title="compile"><code class="xref py py-func docutils literal notranslate"><span class="pre">compile()</span></code></a>). In this case pass a code object instead of a string. If the code object has been compiled with <code class="docutils literal notranslate"><span class="pre">'exec'</span></code> as the <em>mode</em> argument, <a class="reference internal" href="#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a>’s return value will be <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p> <p>Hints: dynamic execution of statements is supported by the <a class="reference internal" href="#exec" title="exec"><code class="xref py py-func docutils literal notranslate"><span class="pre">exec()</span></code></a> function. The <a class="reference internal" href="#globals" title="globals"><code class="xref py py-func docutils literal notranslate"><span class="pre">globals()</span></code></a> and <a class="reference internal" href="#locals" title="locals"><code class="xref py py-func docutils literal notranslate"><span class="pre">locals()</span></code></a> functions returns the current global and local dictionary, respectively, which may be useful to pass around for use by <a class="reference internal" href="#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a> or <a class="reference internal" href="#exec" title="exec"><code class="xref py py-func docutils literal notranslate"><span class="pre">exec()</span></code></a>.</p> <p>See <a class="reference internal" href="ast.html#ast.literal_eval" title="ast.literal_eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">ast.literal_eval()</span></code></a> for a function that can safely evaluate strings with expressions containing only literals.</p> </dd></dl> <span class="target" id="index-1"></span><dl class="function"> <dt id="exec"> <code class="descname">exec</code><span class="sig-paren">(</span><em>object</em><span class="optional">[</span>, <em>globals</em><span class="optional">[</span>, <em>locals</em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#exec" title="Permalink to this definition">¶</a></dt> <dd><p>This function supports dynamic execution of Python code. <em>object</em> must be either a string or a code object. If it is a string, the string is parsed as a suite of Python statements which is then executed (unless a syntax error occurs). <a class="footnote-reference brackets" href="#id2" id="id1">1</a> If it is a code object, it is simply executed. In all cases, the code that’s executed is expected to be valid as file input (see the section “File input” in the Reference Manual). Be aware that the <a class="reference internal" href="../reference/simple_stmts.html#return"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">return</span></code></a> and <a class="reference internal" href="../reference/simple_stmts.html#yield"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">yield</span></code></a> statements may not be used outside of function definitions even within the context of code passed to the <a class="reference internal" href="#exec" title="exec"><code class="xref py py-func docutils literal notranslate"><span class="pre">exec()</span></code></a> function. The return value is <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p> <p>In all cases, if the optional parts are omitted, the code is executed in the current scope. If only <em>globals</em> is provided, it must be a dictionary, which will be used for both the global and the local variables. If <em>globals</em> and <em>locals</em> are given, they are used for the global and local variables, respectively. If provided, <em>locals</em> can be any mapping object. Remember that at module level, globals and locals are the same dictionary. If exec gets two separate objects as <em>globals</em> and <em>locals</em>, the code will be executed as if it were embedded in a class definition.</p> <p>If the <em>globals</em> dictionary does not contain a value for the key <code class="docutils literal notranslate"><span class="pre">__builtins__</span></code>, a reference to the dictionary of the built-in module <a class="reference internal" href="builtins.html#module-builtins" title="builtins: The module that provides the built-in namespace."><code class="xref py py-mod docutils literal notranslate"><span class="pre">builtins</span></code></a> is inserted under that key. That way you can control what builtins are available to the executed code by inserting your own <code class="docutils literal notranslate"><span class="pre">__builtins__</span></code> dictionary into <em>globals</em> before passing it to <a class="reference internal" href="#exec" title="exec"><code class="xref py py-func docutils literal notranslate"><span class="pre">exec()</span></code></a>.</p> <div class="admonition note"> <p class="admonition-title">Note</p> <p>The built-in functions <a class="reference internal" href="#globals" title="globals"><code class="xref py py-func docutils literal notranslate"><span class="pre">globals()</span></code></a> and <a class="reference internal" href="#locals" title="locals"><code class="xref py py-func docutils literal notranslate"><span class="pre">locals()</span></code></a> return the current global and local dictionary, respectively, which may be useful to pass around for use as the second and third argument to <a class="reference internal" href="#exec" title="exec"><code class="xref py py-func docutils literal notranslate"><span class="pre">exec()</span></code></a>.</p> </div> <div class="admonition note"> <p class="admonition-title">Note</p> <p>The default <em>locals</em> act as described for function <a class="reference internal" href="#locals" title="locals"><code class="xref py py-func docutils literal notranslate"><span class="pre">locals()</span></code></a> below: modifications to the default <em>locals</em> dictionary should not be attempted. Pass an explicit <em>locals</em> dictionary if you need to see effects of the code on <em>locals</em> after function <a class="reference internal" href="#exec" title="exec"><code class="xref py py-func docutils literal notranslate"><span class="pre">exec()</span></code></a> returns.</p> </div> </dd></dl> <dl class="function"> <dt id="filter"> <code class="descname">filter</code><span class="sig-paren">(</span><em>function</em>, <em>iterable</em><span class="sig-paren">)</span><a class="headerlink" href="#filter" title="Permalink to this definition">¶</a></dt> <dd><p>Construct an iterator from those elements of <em>iterable</em> for which <em>function</em> returns true. <em>iterable</em> may be either a sequence, a container which supports iteration, or an iterator. If <em>function</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code>, the identity function is assumed, that is, all elements of <em>iterable</em> that are false are removed.</p> <p>Note that <code class="docutils literal notranslate"><span class="pre">filter(function,</span> <span class="pre">iterable)</span></code> is equivalent to the generator expression <code class="docutils literal notranslate"><span class="pre">(item</span> <span class="pre">for</span> <span class="pre">item</span> <span class="pre">in</span> <span class="pre">iterable</span> <span class="pre">if</span> <span class="pre">function(item))</span></code> if function is not <code class="docutils literal notranslate"><span class="pre">None</span></code> and <code class="docutils literal notranslate"><span class="pre">(item</span> <span class="pre">for</span> <span class="pre">item</span> <span class="pre">in</span> <span class="pre">iterable</span> <span class="pre">if</span> <span class="pre">item)</span></code> if function is <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p> <p>See <a class="reference internal" href="itertools.html#itertools.filterfalse" title="itertools.filterfalse"><code class="xref py py-func docutils literal notranslate"><span class="pre">itertools.filterfalse()</span></code></a> for the complementary function that returns elements of <em>iterable</em> for which <em>function</em> returns false.</p> </dd></dl> <dl class="class"> <dt id="float"> <em class="property">class </em><code class="descname">float</code><span class="sig-paren">(</span><span class="optional">[</span><em>x</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#float" title="Permalink to this definition">¶</a></dt> <dd><p id="index-2">Return a floating point number constructed from a number or string <em>x</em>.</p> <p>If the argument is a string, it should contain a decimal number, optionally preceded by a sign, and optionally embedded in whitespace. The optional sign may be <code class="docutils literal notranslate"><span class="pre">'+'</span></code> or <code class="docutils literal notranslate"><span class="pre">'-'</span></code>; a <code class="docutils literal notranslate"><span class="pre">'+'</span></code> sign has no effect on the value produced. The argument may also be a string representing a NaN (not-a-number), or a positive or negative infinity. More precisely, the input must conform to the following grammar after leading and trailing whitespace characters are removed:</p> <pre> <strong id="grammar-token-sign">sign </strong> ::= "+" | "-" <strong id="grammar-token-infinity">infinity </strong> ::= "Infinity" | "inf" <strong id="grammar-token-nan">nan </strong> ::= "nan" <strong id="grammar-token-numeric-value">numeric_value </strong> ::= <a class="reference internal" href="../reference/lexical_analysis.html#grammar-token-floatnumber"><code class="xref docutils literal notranslate"><span class="pre">floatnumber</span></code></a> | <a class="reference internal" href="#grammar-token-infinity"><code class="xref docutils literal notranslate"><span class="pre">infinity</span></code></a> | <a class="reference internal" href="#grammar-token-nan"><code class="xref docutils literal notranslate"><span class="pre">nan</span></code></a> <strong id="grammar-token-numeric-string">numeric_string</strong> ::= [<a class="reference internal" href="string.html#grammar-token-sign"><code class="xref docutils literal notranslate"><span class="pre">sign</span></code></a>] <a class="reference internal" href="#grammar-token-numeric-value"><code class="xref docutils literal notranslate"><span class="pre">numeric_value</span></code></a> </pre> <p>Here <code class="docutils literal notranslate"><span class="pre">floatnumber</span></code> is the form of a Python floating-point literal, described in <a class="reference internal" href="../reference/lexical_analysis.html#floating"><span class="std std-ref">Floating point literals</span></a>. Case is not significant, so, for example, “inf”, “Inf”, “INFINITY” and “iNfINity” are all acceptable spellings for positive infinity.</p> <p>Otherwise, if the argument is an integer or a floating point number, a floating point number with the same value (within Python’s floating point precision) is returned. If the argument is outside the range of a Python float, an <a class="reference internal" href="exceptions.html#OverflowError" title="OverflowError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OverflowError</span></code></a> will be raised.</p> <p>For a general Python object <code class="docutils literal notranslate"><span class="pre">x</span></code>, <code class="docutils literal notranslate"><span class="pre">float(x)</span></code> delegates to <code class="docutils literal notranslate"><span class="pre">x.__float__()</span></code>.</p> <p>If no argument is given, <code class="docutils literal notranslate"><span class="pre">0.0</span></code> is returned.</p> <p>Examples:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">float</span><span class="p">(</span><span class="s1">'+1.23'</span><span class="p">)</span> <span class="go">1.23</span> <span class="gp">>>> </span><span class="nb">float</span><span class="p">(</span><span class="s1">' -12345</span><span class="se">\n</span><span class="s1">'</span><span class="p">)</span> <span class="go">-12345.0</span> <span class="gp">>>> </span><span class="nb">float</span><span class="p">(</span><span class="s1">'1e-003'</span><span class="p">)</span> <span class="go">0.001</span> <span class="gp">>>> </span><span class="nb">float</span><span class="p">(</span><span class="s1">'+1E6'</span><span class="p">)</span> <span class="go">1000000.0</span> <span class="gp">>>> </span><span class="nb">float</span><span class="p">(</span><span class="s1">'-Infinity'</span><span class="p">)</span> <span class="go">-inf</span> </pre></div> </div> <p>The float type is described in <a class="reference internal" href="stdtypes.html#typesnumeric"><span class="std std-ref">Numeric Types — int, float, complex</span></a>.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.6: </span>Grouping digits with underscores as in code literals is allowed.</p> </div> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.7: </span><em>x</em> is now a positional-only parameter.</p> </div> </dd></dl> <span class="target" id="index-3"></span><dl class="function"> <dt id="format"> <code class="descname">format</code><span class="sig-paren">(</span><em>value</em><span class="optional">[</span>, <em>format_spec</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#format" title="Permalink to this definition">¶</a></dt> <dd><p>Convert a <em>value</em> to a “formatted” representation, as controlled by <em>format_spec</em>. The interpretation of <em>format_spec</em> will depend on the type of the <em>value</em> argument, however there is a standard formatting syntax that is used by most built-in types: <a class="reference internal" href="string.html#formatspec"><span class="std std-ref">Format Specification Mini-Language</span></a>.</p> <p>The default <em>format_spec</em> is an empty string which usually gives the same effect as calling <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-func docutils literal notranslate"><span class="pre">str(value)</span></code></a>.</p> <p>A call to <code class="docutils literal notranslate"><span class="pre">format(value,</span> <span class="pre">format_spec)</span></code> is translated to <code class="docutils literal notranslate"><span class="pre">type(value).__format__(value,</span> <span class="pre">format_spec)</span></code> which bypasses the instance dictionary when searching for the value’s <a class="reference internal" href="../reference/datamodel.html#object.__format__" title="object.__format__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__format__()</span></code></a> method. A <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> exception is raised if the method search reaches <a class="reference internal" href="#object" title="object"><code class="xref py py-mod docutils literal notranslate"><span class="pre">object</span></code></a> and the <em>format_spec</em> is non-empty, or if either the <em>format_spec</em> or the return value are not strings.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.4: </span><code class="docutils literal notranslate"><span class="pre">object().__format__(format_spec)</span></code> raises <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> if <em>format_spec</em> is not an empty string.</p> </div> </dd></dl> <span class="target" id="func-frozenset"></span><dl class="class"> <dt> <em class="property">class </em><code class="descname">frozenset</code><span class="sig-paren">(</span><span class="optional">[</span><em>iterable</em><span class="optional">]</span><span class="sig-paren">)</span></dt> <dd><p>Return a new <a class="reference internal" href="stdtypes.html#frozenset" title="frozenset"><code class="xref py py-class docutils literal notranslate"><span class="pre">frozenset</span></code></a> object, optionally with elements taken from <em>iterable</em>. <code class="docutils literal notranslate"><span class="pre">frozenset</span></code> is a built-in class. See <a class="reference internal" href="stdtypes.html#frozenset" title="frozenset"><code class="xref py py-class docutils literal notranslate"><span class="pre">frozenset</span></code></a> and <a class="reference internal" href="stdtypes.html#types-set"><span class="std std-ref">Set Types — set, frozenset</span></a> for documentation about this class.</p> <p>For other containers see the built-in <a class="reference internal" href="stdtypes.html#set" title="set"><code class="xref py py-class docutils literal notranslate"><span class="pre">set</span></code></a>, <a class="reference internal" href="stdtypes.html#list" title="list"><code class="xref py py-class docutils literal notranslate"><span class="pre">list</span></code></a>, <a class="reference internal" href="stdtypes.html#tuple" title="tuple"><code class="xref py py-class docutils literal notranslate"><span class="pre">tuple</span></code></a>, and <a class="reference internal" href="stdtypes.html#dict" title="dict"><code class="xref py py-class docutils literal notranslate"><span class="pre">dict</span></code></a> classes, as well as the <a class="reference internal" href="collections.html#module-collections" title="collections: Container datatypes"><code class="xref py py-mod docutils literal notranslate"><span class="pre">collections</span></code></a> module.</p> </dd></dl> <dl class="function"> <dt id="getattr"> <code class="descname">getattr</code><span class="sig-paren">(</span><em>object</em>, <em>name</em><span class="optional">[</span>, <em>default</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#getattr" title="Permalink to this definition">¶</a></dt> <dd><p>Return the value of the named attribute of <em>object</em>. <em>name</em> must be a string. If the string is the name of one of the object’s attributes, the result is the value of that attribute. For example, <code class="docutils literal notranslate"><span class="pre">getattr(x,</span> <span class="pre">'foobar')</span></code> is equivalent to <code class="docutils literal notranslate"><span class="pre">x.foobar</span></code>. If the named attribute does not exist, <em>default</em> is returned if provided, otherwise <a class="reference internal" href="exceptions.html#AttributeError" title="AttributeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">AttributeError</span></code></a> is raised.</p> </dd></dl> <dl class="function"> <dt id="globals"> <code class="descname">globals</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#globals" title="Permalink to this definition">¶</a></dt> <dd><p>Return a dictionary representing the current global symbol table. This is always the dictionary of the current module (inside a function or method, this is the module where it is defined, not the module from which it is called).</p> </dd></dl> <dl class="function"> <dt id="hasattr"> <code class="descname">hasattr</code><span class="sig-paren">(</span><em>object</em>, <em>name</em><span class="sig-paren">)</span><a class="headerlink" href="#hasattr" title="Permalink to this definition">¶</a></dt> <dd><p>The arguments are an object and a string. The result is <code class="docutils literal notranslate"><span class="pre">True</span></code> if the string is the name of one of the object’s attributes, <code class="docutils literal notranslate"><span class="pre">False</span></code> if not. (This is implemented by calling <code class="docutils literal notranslate"><span class="pre">getattr(object,</span> <span class="pre">name)</span></code> and seeing whether it raises an <a class="reference internal" href="exceptions.html#AttributeError" title="AttributeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">AttributeError</span></code></a> or not.)</p> </dd></dl> <dl class="function"> <dt id="hash"> <code class="descname">hash</code><span class="sig-paren">(</span><em>object</em><span class="sig-paren">)</span><a class="headerlink" href="#hash" title="Permalink to this definition">¶</a></dt> <dd><p>Return the hash value of the object (if it has one). Hash values are integers. They are used to quickly compare dictionary keys during a dictionary lookup. Numeric values that compare equal have the same hash value (even if they are of different types, as is the case for 1 and 1.0).</p> <div class="admonition note"> <p class="admonition-title">Note</p> <p>For objects with custom <a class="reference internal" href="../reference/datamodel.html#object.__hash__" title="object.__hash__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__hash__()</span></code></a> methods, note that <a class="reference internal" href="#hash" title="hash"><code class="xref py py-func docutils literal notranslate"><span class="pre">hash()</span></code></a> truncates the return value based on the bit width of the host machine. See <a class="reference internal" href="../reference/datamodel.html#object.__hash__" title="object.__hash__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__hash__()</span></code></a> for details.</p> </div> </dd></dl> <dl class="function"> <dt id="help"> <code class="descname">help</code><span class="sig-paren">(</span><span class="optional">[</span><em>object</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#help" title="Permalink to this definition">¶</a></dt> <dd><p>Invoke the built-in help system. (This function is intended for interactive use.) If no argument is given, the interactive help system starts on the interpreter console. If the argument is a string, then the string is looked up as the name of a module, function, class, method, keyword, or documentation topic, and a help page is printed on the console. If the argument is any other kind of object, a help page on the object is generated.</p> <p>Note that if a slash(/) appears in the parameter list of a function, when invoking <a class="reference internal" href="#help" title="help"><code class="xref py py-func docutils literal notranslate"><span class="pre">help()</span></code></a>, it means that the parameters prior to the slash are positional-only. For more info, see <a class="reference internal" href="../faq/programming.html#faq-positional-only-arguments"><span class="std std-ref">the FAQ entry on positional-only parameters</span></a>.</p> <p>This function is added to the built-in namespace by the <a class="reference internal" href="site.html#module-site" title="site: Module responsible for site-specific configuration."><code class="xref py py-mod docutils literal notranslate"><span class="pre">site</span></code></a> module.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.4: </span>Changes to <a class="reference internal" href="pydoc.html#module-pydoc" title="pydoc: Documentation generator and online help system."><code class="xref py py-mod docutils literal notranslate"><span class="pre">pydoc</span></code></a> and <a class="reference internal" href="inspect.html#module-inspect" title="inspect: Extract information and source code from live objects."><code class="xref py py-mod docutils literal notranslate"><span class="pre">inspect</span></code></a> mean that the reported signatures for callables are now more comprehensive and consistent.</p> </div> </dd></dl> <dl class="function"> <dt id="hex"> <code class="descname">hex</code><span class="sig-paren">(</span><em>x</em><span class="sig-paren">)</span><a class="headerlink" href="#hex" title="Permalink to this definition">¶</a></dt> <dd><p>Convert an integer number to a lowercase hexadecimal string prefixed with “0x”. If <em>x</em> is not a Python <a class="reference internal" href="#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a> object, it has to define an <a class="reference internal" href="../reference/datamodel.html#object.__index__" title="object.__index__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__index__()</span></code></a> method that returns an integer. Some examples:</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">hex</span><span class="p">(</span><span class="mi">255</span><span class="p">)</span> <span class="go">'0xff'</span> <span class="gp">>>> </span><span class="nb">hex</span><span class="p">(</span><span class="o">-</span><span class="mi">42</span><span class="p">)</span> <span class="go">'-0x2a'</span> </pre></div> </div> <p>If you want to convert an integer number to an uppercase or lower hexadecimal string with prefix or not, you can use either of the following ways:</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="s1">'</span><span class="si">%#x</span><span class="s1">'</span> <span class="o">%</span> <span class="mi">255</span><span class="p">,</span> <span class="s1">'</span><span class="si">%x</span><span class="s1">'</span> <span class="o">%</span> <span class="mi">255</span><span class="p">,</span> <span class="s1">'</span><span class="si">%X</span><span class="s1">'</span> <span class="o">%</span> <span class="mi">255</span> <span class="go">('0xff', 'ff', 'FF')</span> <span class="gp">>>> </span><span class="nb">format</span><span class="p">(</span><span class="mi">255</span><span class="p">,</span> <span class="s1">'#x'</span><span class="p">),</span> <span class="nb">format</span><span class="p">(</span><span class="mi">255</span><span class="p">,</span> <span class="s1">'x'</span><span class="p">),</span> <span class="nb">format</span><span class="p">(</span><span class="mi">255</span><span class="p">,</span> <span class="s1">'X'</span><span class="p">)</span> <span class="go">('0xff', 'ff', 'FF')</span> <span class="gp">>>> </span><span class="n">f</span><span class="s1">'</span><span class="si">{255:#x}</span><span class="s1">'</span><span class="p">,</span> <span class="n">f</span><span class="s1">'</span><span class="si">{255:x}</span><span class="s1">'</span><span class="p">,</span> <span class="n">f</span><span class="s1">'</span><span class="si">{255:X}</span><span class="s1">'</span> <span class="go">('0xff', 'ff', 'FF')</span> </pre></div> </div> <p>See also <a class="reference internal" href="#format" title="format"><code class="xref py py-func docutils literal notranslate"><span class="pre">format()</span></code></a> for more information.</p> <p>See also <a class="reference internal" href="#int" title="int"><code class="xref py py-func docutils literal notranslate"><span class="pre">int()</span></code></a> for converting a hexadecimal string to an integer using a base of 16.</p> <div class="admonition note"> <p class="admonition-title">Note</p> <p>To obtain a hexadecimal string representation for a float, use the <a class="reference internal" href="stdtypes.html#float.hex" title="float.hex"><code class="xref py py-meth docutils literal notranslate"><span class="pre">float.hex()</span></code></a> method.</p> </div> </dd></dl> <dl class="function"> <dt id="id"> <code class="descname">id</code><span class="sig-paren">(</span><em>object</em><span class="sig-paren">)</span><a class="headerlink" href="#id" title="Permalink to this definition">¶</a></dt> <dd><p>Return the “identity” of an object. This is an integer which is guaranteed to be unique and constant for this object during its lifetime. Two objects with non-overlapping lifetimes may have the same <a class="reference internal" href="#id" title="id"><code class="xref py py-func docutils literal notranslate"><span class="pre">id()</span></code></a> value.</p> <div class="impl-detail compound"> <p><strong>CPython implementation detail:</strong> This is the address of the object in memory.</p> </div> </dd></dl> <dl class="function"> <dt id="input"> <code class="descname">input</code><span class="sig-paren">(</span><span class="optional">[</span><em>prompt</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#input" title="Permalink to this definition">¶</a></dt> <dd><p>If the <em>prompt</em> argument is present, it is written to standard output without a trailing newline. The function then reads a line from input, converts it to a string (stripping a trailing newline), and returns that. When EOF is read, <a class="reference internal" href="exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a> is raised. Example:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">s</span> <span class="o">=</span> <span class="nb">input</span><span class="p">(</span><span class="s1">'--> '</span><span class="p">)</span> <span class="go">--> Monty Python's Flying Circus</span> <span class="gp">>>> </span><span class="n">s</span> <span class="go">"Monty Python's Flying Circus"</span> </pre></div> </div> <p>If the <a class="reference internal" href="readline.html#module-readline" title="readline: GNU readline support for Python. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">readline</span></code></a> module was loaded, then <a class="reference internal" href="#input" title="input"><code class="xref py py-func docutils literal notranslate"><span class="pre">input()</span></code></a> will use it to provide elaborate line editing and history features.</p> </dd></dl> <dl class="class"> <dt id="int"> <em class="property">class </em><code class="descname">int</code><span class="sig-paren">(</span><span class="optional">[</span><em>x</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#int" title="Permalink to this definition">¶</a></dt> <dt> <em class="property">class </em><code class="descname">int</code><span class="sig-paren">(</span><em>x</em>, <em>base=10</em><span class="sig-paren">)</span></dt> <dd><p>Return an integer object constructed from a number or string <em>x</em>, or return <code class="docutils literal notranslate"><span class="pre">0</span></code> if no arguments are given. If <em>x</em> defines <a class="reference internal" href="../reference/datamodel.html#object.__int__" title="object.__int__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__int__()</span></code></a>, <code class="docutils literal notranslate"><span class="pre">int(x)</span></code> returns <code class="docutils literal notranslate"><span class="pre">x.__int__()</span></code>. If <em>x</em> defines <a class="reference internal" href="../reference/datamodel.html#object.__trunc__" title="object.__trunc__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__trunc__()</span></code></a>, it returns <code class="docutils literal notranslate"><span class="pre">x.__trunc__()</span></code>. For floating point numbers, this truncates towards zero.</p> <p>If <em>x</em> is not a number or if <em>base</em> is given, then <em>x</em> must be a string, <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>, or <a class="reference internal" href="stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a> instance representing an <a class="reference internal" href="../reference/lexical_analysis.html#integers"><span class="std std-ref">integer literal</span></a> in radix <em>base</em>. Optionally, the literal can be preceded by <code class="docutils literal notranslate"><span class="pre">+</span></code> or <code class="docutils literal notranslate"><span class="pre">-</span></code> (with no space in between) and surrounded by whitespace. A base-n literal consists of the digits 0 to n-1, with <code class="docutils literal notranslate"><span class="pre">a</span></code> to <code class="docutils literal notranslate"><span class="pre">z</span></code> (or <code class="docutils literal notranslate"><span class="pre">A</span></code> to <code class="docutils literal notranslate"><span class="pre">Z</span></code>) having values 10 to 35. The default <em>base</em> is 10. The allowed values are 0 and 2–36. Base-2, -8, and -16 literals can be optionally prefixed with <code class="docutils literal notranslate"><span class="pre">0b</span></code>/<code class="docutils literal notranslate"><span class="pre">0B</span></code>, <code class="docutils literal notranslate"><span class="pre">0o</span></code>/<code class="docutils literal notranslate"><span class="pre">0O</span></code>, or <code class="docutils literal notranslate"><span class="pre">0x</span></code>/<code class="docutils literal notranslate"><span class="pre">0X</span></code>, as with integer literals in code. Base 0 means to interpret exactly as a code literal, so that the actual base is 2, 8, 10, or 16, and so that <code class="docutils literal notranslate"><span class="pre">int('010',</span> <span class="pre">0)</span></code> is not legal, while <code class="docutils literal notranslate"><span class="pre">int('010')</span></code> is, as well as <code class="docutils literal notranslate"><span class="pre">int('010',</span> <span class="pre">8)</span></code>.</p> <p>The integer type is described in <a class="reference internal" href="stdtypes.html#typesnumeric"><span class="std std-ref">Numeric Types — int, float, complex</span></a>.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.4: </span>If <em>base</em> is not an instance of <a class="reference internal" href="#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a> and the <em>base</em> object has a <a class="reference internal" href="../reference/datamodel.html#object.__index__" title="object.__index__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">base.__index__</span></code></a> method, that method is called to obtain an integer for the base. Previous versions used <a class="reference internal" href="../reference/datamodel.html#object.__int__" title="object.__int__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">base.__int__</span></code></a> instead of <a class="reference internal" href="../reference/datamodel.html#object.__index__" title="object.__index__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">base.__index__</span></code></a>.</p> </div> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.6: </span>Grouping digits with underscores as in code literals is allowed.</p> </div> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.7: </span><em>x</em> is now a positional-only parameter.</p> </div> </dd></dl> <dl class="function"> <dt id="isinstance"> <code class="descname">isinstance</code><span class="sig-paren">(</span><em>object</em>, <em>classinfo</em><span class="sig-paren">)</span><a class="headerlink" href="#isinstance" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if the <em>object</em> argument is an instance of the <em>classinfo</em> argument, or of a (direct, indirect or <a class="reference internal" href="../glossary.html#term-abstract-base-class"><span class="xref std std-term">virtual</span></a>) subclass thereof. If <em>object</em> is not an object of the given type, the function always returns false. If <em>classinfo</em> is a tuple of type objects (or recursively, other such tuples), return true if <em>object</em> is an instance of any of the types. If <em>classinfo</em> is not a type or tuple of types and such tuples, a <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> exception is raised.</p> </dd></dl> <dl class="function"> <dt id="issubclass"> <code class="descname">issubclass</code><span class="sig-paren">(</span><em>class</em>, <em>classinfo</em><span class="sig-paren">)</span><a class="headerlink" href="#issubclass" title="Permalink to this definition">¶</a></dt> <dd><p>Return true if <em>class</em> is a subclass (direct, indirect or <a class="reference internal" href="../glossary.html#term-abstract-base-class"><span class="xref std std-term">virtual</span></a>) of <em>classinfo</em>. A class is considered a subclass of itself. <em>classinfo</em> may be a tuple of class objects, in which case every entry in <em>classinfo</em> will be checked. In any other case, a <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> exception is raised.</p> </dd></dl> <dl class="function"> <dt id="iter"> <code class="descname">iter</code><span class="sig-paren">(</span><em>object</em><span class="optional">[</span>, <em>sentinel</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#iter" title="Permalink to this definition">¶</a></dt> <dd><p>Return an <a class="reference internal" href="../glossary.html#term-iterator"><span class="xref std std-term">iterator</span></a> object. The first argument is interpreted very differently depending on the presence of the second argument. Without a second argument, <em>object</em> must be a collection object which supports the iteration protocol (the <a class="reference internal" href="../reference/datamodel.html#object.__iter__" title="object.__iter__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__iter__()</span></code></a> method), or it must support the sequence protocol (the <a class="reference internal" href="../reference/datamodel.html#object.__getitem__" title="object.__getitem__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__getitem__()</span></code></a> method with integer arguments starting at <code class="docutils literal notranslate"><span class="pre">0</span></code>). If it does not support either of those protocols, <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> is raised. If the second argument, <em>sentinel</em>, is given, then <em>object</em> must be a callable object. The iterator created in this case will call <em>object</em> with no arguments for each call to its <a class="reference internal" href="stdtypes.html#iterator.__next__" title="iterator.__next__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__next__()</span></code></a> method; if the value returned is equal to <em>sentinel</em>, <a class="reference internal" href="exceptions.html#StopIteration" title="StopIteration"><code class="xref py py-exc docutils literal notranslate"><span class="pre">StopIteration</span></code></a> will be raised, otherwise the value will be returned.</p> <p>See also <a class="reference internal" href="stdtypes.html#typeiter"><span class="std std-ref">Iterator Types</span></a>.</p> <p>One useful application of the second form of <a class="reference internal" href="#iter" title="iter"><code class="xref py py-func docutils literal notranslate"><span class="pre">iter()</span></code></a> is to build a block-reader. For example, reading fixed-width blocks from a binary database file until the end of file is reached:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">functools</span> <span class="k">import</span> <span class="n">partial</span> <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'mydata.db'</span><span class="p">,</span> <span class="s1">'rb'</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span> <span class="k">for</span> <span class="n">block</span> <span class="ow">in</span> <span class="nb">iter</span><span class="p">(</span><span class="n">partial</span><span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="n">read</span><span class="p">,</span> <span class="mi">64</span><span class="p">),</span> <span class="sa">b</span><span class="s1">''</span><span class="p">):</span> <span class="n">process_block</span><span class="p">(</span><span class="n">block</span><span class="p">)</span> </pre></div> </div> </dd></dl> <dl class="function"> <dt id="len"> <code class="descname">len</code><span class="sig-paren">(</span><em>s</em><span class="sig-paren">)</span><a class="headerlink" href="#len" title="Permalink to this definition">¶</a></dt> <dd><p>Return the length (the number of items) of an object. The argument may be a sequence (such as a string, bytes, tuple, list, or range) or a collection (such as a dictionary, set, or frozen set).</p> </dd></dl> <span class="target" id="func-list"></span><dl class="class"> <dt> <em class="property">class </em><code class="descname">list</code><span class="sig-paren">(</span><span class="optional">[</span><em>iterable</em><span class="optional">]</span><span class="sig-paren">)</span></dt> <dd><p>Rather than being a function, <a class="reference internal" href="stdtypes.html#list" title="list"><code class="xref py py-class docutils literal notranslate"><span class="pre">list</span></code></a> is actually a mutable sequence type, as documented in <a class="reference internal" href="stdtypes.html#typesseq-list"><span class="std std-ref">Lists</span></a> and <a class="reference internal" href="stdtypes.html#typesseq"><span class="std std-ref">Sequence Types — list, tuple, range</span></a>.</p> </dd></dl> <dl class="function"> <dt id="locals"> <code class="descname">locals</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#locals" title="Permalink to this definition">¶</a></dt> <dd><p>Update and return a dictionary representing the current local symbol table. Free variables are returned by <a class="reference internal" href="#locals" title="locals"><code class="xref py py-func docutils literal notranslate"><span class="pre">locals()</span></code></a> when it is called in function blocks, but not in class blocks. Note that at the module level, <a class="reference internal" href="#locals" title="locals"><code class="xref py py-func docutils literal notranslate"><span class="pre">locals()</span></code></a> and <a class="reference internal" href="#globals" title="globals"><code class="xref py py-func docutils literal notranslate"><span class="pre">globals()</span></code></a> are the same dictionary.</p> <div class="admonition note"> <p class="admonition-title">Note</p> <p>The contents of this dictionary should not be modified; changes may not affect the values of local and free variables used by the interpreter.</p> </div> </dd></dl> <dl class="function"> <dt id="map"> <code class="descname">map</code><span class="sig-paren">(</span><em>function</em>, <em>iterable</em>, <em>...</em><span class="sig-paren">)</span><a class="headerlink" href="#map" title="Permalink to this definition">¶</a></dt> <dd><p>Return an iterator that applies <em>function</em> to every item of <em>iterable</em>, yielding the results. If additional <em>iterable</em> arguments are passed, <em>function</em> must take that many arguments and is applied to the items from all iterables in parallel. With multiple iterables, the iterator stops when the shortest iterable is exhausted. For cases where the function inputs are already arranged into argument tuples, see <a class="reference internal" href="itertools.html#itertools.starmap" title="itertools.starmap"><code class="xref py py-func docutils literal notranslate"><span class="pre">itertools.starmap()</span></code></a>.</p> </dd></dl> <dl class="function"> <dt id="max"> <code class="descname">max</code><span class="sig-paren">(</span><em>iterable</em>, <em>*</em><span class="optional">[</span>, <em>key</em>, <em>default</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#max" title="Permalink to this definition">¶</a></dt> <dt> <code class="descname">max</code><span class="sig-paren">(</span><em>arg1</em>, <em>arg2</em>, <em>*args</em><span class="optional">[</span>, <em>key</em><span class="optional">]</span><span class="sig-paren">)</span></dt> <dd><p>Return the largest item in an iterable or the largest of two or more arguments.</p> <p>If one positional argument is provided, it should be an <a class="reference internal" href="../glossary.html#term-iterable"><span class="xref std std-term">iterable</span></a>. The largest item in the iterable is returned. If two or more positional arguments are provided, the largest of the positional arguments is returned.</p> <p>There are two optional keyword-only arguments. The <em>key</em> argument specifies a one-argument ordering function like that used for <a class="reference internal" href="stdtypes.html#list.sort" title="list.sort"><code class="xref py py-meth docutils literal notranslate"><span class="pre">list.sort()</span></code></a>. The <em>default</em> argument specifies an object to return if the provided iterable is empty. If the iterable is empty and <em>default</em> is not provided, a <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> is raised.</p> <p>If multiple items are maximal, the function returns the first one encountered. This is consistent with other sort-stability preserving tools such as <code class="docutils literal notranslate"><span class="pre">sorted(iterable,</span> <span class="pre">key=keyfunc,</span> <span class="pre">reverse=True)[0]</span></code> and <code class="docutils literal notranslate"><span class="pre">heapq.nlargest(1,</span> <span class="pre">iterable,</span> <span class="pre">key=keyfunc)</span></code>.</p> <div class="versionadded"> <p><span class="versionmodified added">New in version 3.4: </span>The <em>default</em> keyword-only argument.</p> </div> </dd></dl> <span class="target" id="func-memoryview"></span><dl class="function"> <dt> <code class="descname">memoryview</code><span class="sig-paren">(</span><em>obj</em><span class="sig-paren">)</span></dt> <dd><p>Return a “memory view” object created from the given argument. See <a class="reference internal" href="stdtypes.html#typememoryview"><span class="std std-ref">Memory Views</span></a> for more information.</p> </dd></dl> <dl class="function"> <dt id="min"> <code class="descname">min</code><span class="sig-paren">(</span><em>iterable</em>, <em>*</em><span class="optional">[</span>, <em>key</em>, <em>default</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#min" title="Permalink to this definition">¶</a></dt> <dt> <code class="descname">min</code><span class="sig-paren">(</span><em>arg1</em>, <em>arg2</em>, <em>*args</em><span class="optional">[</span>, <em>key</em><span class="optional">]</span><span class="sig-paren">)</span></dt> <dd><p>Return the smallest item in an iterable or the smallest of two or more arguments.</p> <p>If one positional argument is provided, it should be an <a class="reference internal" href="../glossary.html#term-iterable"><span class="xref std std-term">iterable</span></a>. The smallest item in the iterable is returned. If two or more positional arguments are provided, the smallest of the positional arguments is returned.</p> <p>There are two optional keyword-only arguments. The <em>key</em> argument specifies a one-argument ordering function like that used for <a class="reference internal" href="stdtypes.html#list.sort" title="list.sort"><code class="xref py py-meth docutils literal notranslate"><span class="pre">list.sort()</span></code></a>. The <em>default</em> argument specifies an object to return if the provided iterable is empty. If the iterable is empty and <em>default</em> is not provided, a <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> is raised.</p> <p>If multiple items are minimal, the function returns the first one encountered. This is consistent with other sort-stability preserving tools such as <code class="docutils literal notranslate"><span class="pre">sorted(iterable,</span> <span class="pre">key=keyfunc)[0]</span></code> and <code class="docutils literal notranslate"><span class="pre">heapq.nsmallest(1,</span> <span class="pre">iterable,</span> <span class="pre">key=keyfunc)</span></code>.</p> <div class="versionadded"> <p><span class="versionmodified added">New in version 3.4: </span>The <em>default</em> keyword-only argument.</p> </div> </dd></dl> <dl class="function"> <dt id="next"> <code class="descname">next</code><span class="sig-paren">(</span><em>iterator</em><span class="optional">[</span>, <em>default</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#next" title="Permalink to this definition">¶</a></dt> <dd><p>Retrieve the next item from the <em>iterator</em> by calling its <a class="reference internal" href="stdtypes.html#iterator.__next__" title="iterator.__next__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__next__()</span></code></a> method. If <em>default</em> is given, it is returned if the iterator is exhausted, otherwise <a class="reference internal" href="exceptions.html#StopIteration" title="StopIteration"><code class="xref py py-exc docutils literal notranslate"><span class="pre">StopIteration</span></code></a> is raised.</p> </dd></dl> <dl class="class"> <dt id="object"> <em class="property">class </em><code class="descname">object</code><a class="headerlink" href="#object" title="Permalink to this definition">¶</a></dt> <dd><p>Return a new featureless object. <a class="reference internal" href="#object" title="object"><code class="xref py py-class docutils literal notranslate"><span class="pre">object</span></code></a> is a base for all classes. It has the methods that are common to all instances of Python classes. This function does not accept any arguments.</p> <div class="admonition note"> <p class="admonition-title">Note</p> <p><a class="reference internal" href="#object" title="object"><code class="xref py py-class docutils literal notranslate"><span class="pre">object</span></code></a> does <em>not</em> have a <a class="reference internal" href="stdtypes.html#object.__dict__" title="object.__dict__"><code class="xref py py-attr docutils literal notranslate"><span class="pre">__dict__</span></code></a>, so you can’t assign arbitrary attributes to an instance of the <a class="reference internal" href="#object" title="object"><code class="xref py py-class docutils literal notranslate"><span class="pre">object</span></code></a> class.</p> </div> </dd></dl> <dl class="function"> <dt id="oct"> <code class="descname">oct</code><span class="sig-paren">(</span><em>x</em><span class="sig-paren">)</span><a class="headerlink" href="#oct" title="Permalink to this definition">¶</a></dt> <dd><p>Convert an integer number to an octal string prefixed with “0o”. The result is a valid Python expression. If <em>x</em> is not a Python <a class="reference internal" href="#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a> object, it has to define an <a class="reference internal" href="../reference/datamodel.html#object.__index__" title="object.__index__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__index__()</span></code></a> method that returns an integer. For example:</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="nb">oct</span><span class="p">(</span><span class="mi">8</span><span class="p">)</span> <span class="go">'0o10'</span> <span class="gp">>>> </span><span class="nb">oct</span><span class="p">(</span><span class="o">-</span><span class="mi">56</span><span class="p">)</span> <span class="go">'-0o70'</span> </pre></div> </div> <p>If you want to convert an integer number to octal string either with prefix “0o” or not, you can use either of the following ways.</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="s1">'</span><span class="si">%#o</span><span class="s1">'</span> <span class="o">%</span> <span class="mi">10</span><span class="p">,</span> <span class="s1">'</span><span class="si">%o</span><span class="s1">'</span> <span class="o">%</span> <span class="mi">10</span> <span class="go">('0o12', '12')</span> <span class="gp">>>> </span><span class="nb">format</span><span class="p">(</span><span class="mi">10</span><span class="p">,</span> <span class="s1">'#o'</span><span class="p">),</span> <span class="nb">format</span><span class="p">(</span><span class="mi">10</span><span class="p">,</span> <span class="s1">'o'</span><span class="p">)</span> <span class="go">('0o12', '12')</span> <span class="gp">>>> </span><span class="n">f</span><span class="s1">'</span><span class="si">{10:#o}</span><span class="s1">'</span><span class="p">,</span> <span class="n">f</span><span class="s1">'</span><span class="si">{10:o}</span><span class="s1">'</span> <span class="go">('0o12', '12')</span> </pre></div> </div> <p>See also <a class="reference internal" href="#format" title="format"><code class="xref py py-func docutils literal notranslate"><span class="pre">format()</span></code></a> for more information.</p> <blockquote> <div><span class="target" id="index-4"></span></div></blockquote> </dd></dl> <dl class="function"> <dt id="open"> <code class="descname">open</code><span class="sig-paren">(</span><em>file</em>, <em>mode='r'</em>, <em>buffering=-1</em>, <em>encoding=None</em>, <em>errors=None</em>, <em>newline=None</em>, <em>closefd=True</em>, <em>opener=None</em><span class="sig-paren">)</span><a class="headerlink" href="#open" title="Permalink to this definition">¶</a></dt> <dd><p>Open <em>file</em> and return a corresponding <a class="reference internal" href="../glossary.html#term-file-object"><span class="xref std std-term">file object</span></a>. If the file cannot be opened, an <a class="reference internal" href="exceptions.html#OSError" title="OSError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OSError</span></code></a> is raised.</p> <p><em>file</em> is a <a class="reference internal" href="../glossary.html#term-path-like-object"><span class="xref std std-term">path-like object</span></a> giving the pathname (absolute or relative to the current working directory) of the file to be opened or an integer file descriptor of the file to be wrapped. (If a file descriptor is given, it is closed when the returned I/O object is closed, unless <em>closefd</em> is set to <code class="docutils literal notranslate"><span class="pre">False</span></code>.)</p> <p><em>mode</em> is an optional string that specifies the mode in which the file is opened. It defaults to <code class="docutils literal notranslate"><span class="pre">'r'</span></code> which means open for reading in text mode. Other common values are <code class="docutils literal notranslate"><span class="pre">'w'</span></code> for writing (truncating the file if it already exists), <code class="docutils literal notranslate"><span class="pre">'x'</span></code> for exclusive creation and <code class="docutils literal notranslate"><span class="pre">'a'</span></code> for appending (which on <em>some</em> Unix systems, means that <em>all</em> writes append to the end of the file regardless of the current seek position). In text mode, if <em>encoding</em> is not specified the encoding used is platform dependent: <code class="docutils literal notranslate"><span class="pre">locale.getpreferredencoding(False)</span></code> is called to get the current locale encoding. (For reading and writing raw bytes use binary mode and leave <em>encoding</em> unspecified.) The available modes are:</p> <span class="target" id="filemodes"></span><table class="docutils align-center" id="index-5"> <colgroup> <col style="width: 13%" /> <col style="width: 88%" /> </colgroup> <thead> <tr class="row-odd"><th class="head"><p>Character</p></th> <th class="head"><p>Meaning</p></th> </tr> </thead> <tbody> <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'r'</span></code></p></td> <td><p>open for reading (default)</p></td> </tr> <tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'w'</span></code></p></td> <td><p>open for writing, truncating the file first</p></td> </tr> <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'x'</span></code></p></td> <td><p>open for exclusive creation, failing if the file already exists</p></td> </tr> <tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'a'</span></code></p></td> <td><p>open for writing, appending to the end of the file if it exists</p></td> </tr> <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'b'</span></code></p></td> <td><p>binary mode</p></td> </tr> <tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'t'</span></code></p></td> <td><p>text mode (default)</p></td> </tr> <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'+'</span></code></p></td> <td><p>open a disk file for updating (reading and writing)</p></td> </tr> </tbody> </table> <p>The default mode is <code class="docutils literal notranslate"><span class="pre">'r'</span></code> (open for reading text, synonym of <code class="docutils literal notranslate"><span class="pre">'rt'</span></code>). For binary read-write access, the mode <code class="docutils literal notranslate"><span class="pre">'w+b'</span></code> opens and truncates the file to 0 bytes. <code class="docutils literal notranslate"><span class="pre">'r+b'</span></code> opens the file without truncation.</p> <p>As mentioned in the <a class="reference internal" href="io.html#io-overview"><span class="std std-ref">Overview</span></a>, Python distinguishes between binary and text I/O. Files opened in binary mode (including <code class="docutils literal notranslate"><span class="pre">'b'</span></code> in the <em>mode</em> argument) return contents as <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> objects without any decoding. In text mode (the default, or when <code class="docutils literal notranslate"><span class="pre">'t'</span></code> is included in the <em>mode</em> argument), the contents of the file are returned as <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a>, the bytes having been first decoded using a platform-dependent encoding or using the specified <em>encoding</em> if given.</p> <p>There is an additional mode character permitted, <code class="docutils literal notranslate"><span class="pre">'U'</span></code>, which no longer has any effect, and is considered deprecated. It previously enabled <a class="reference internal" href="../glossary.html#term-universal-newlines"><span class="xref std std-term">universal newlines</span></a> in text mode, which became the default behaviour in Python 3.0. Refer to the documentation of the <a class="reference internal" href="#open-newline-parameter"><span class="std std-ref">newline</span></a> parameter for further details.</p> <div class="admonition note"> <p class="admonition-title">Note</p> <p>Python doesn’t depend on the underlying operating system’s notion of text files; all the processing is done by Python itself, and is therefore platform-independent.</p> </div> <p><em>buffering</em> is an optional integer used to set the buffering policy. Pass 0 to switch buffering off (only allowed in binary mode), 1 to select line buffering (only usable in text mode), and an integer > 1 to indicate the size in bytes of a fixed-size chunk buffer. When no <em>buffering</em> argument is given, the default buffering policy works as follows:</p> <ul class="simple"> <li><p>Binary files are buffered in fixed-size chunks; the size of the buffer is chosen using a heuristic trying to determine the underlying device’s “block size” and falling back on <a class="reference internal" href="io.html#io.DEFAULT_BUFFER_SIZE" title="io.DEFAULT_BUFFER_SIZE"><code class="xref py py-attr docutils literal notranslate"><span class="pre">io.DEFAULT_BUFFER_SIZE</span></code></a>. On many systems, the buffer will typically be 4096 or 8192 bytes long.</p></li> <li><p>“Interactive” text files (files for which <a class="reference internal" href="io.html#io.IOBase.isatty" title="io.IOBase.isatty"><code class="xref py py-meth docutils literal notranslate"><span class="pre">isatty()</span></code></a> returns <code class="docutils literal notranslate"><span class="pre">True</span></code>) use line buffering. Other text files use the policy described above for binary files.</p></li> </ul> <p><em>encoding</em> is the name of the encoding used to decode or encode the file. This should only be used in text mode. The default encoding is platform dependent (whatever <a class="reference internal" href="locale.html#locale.getpreferredencoding" title="locale.getpreferredencoding"><code class="xref py py-func docutils literal notranslate"><span class="pre">locale.getpreferredencoding()</span></code></a> returns), but any <a class="reference internal" href="../glossary.html#term-text-encoding"><span class="xref std std-term">text encoding</span></a> supported by Python can be used. See the <a class="reference internal" href="codecs.html#module-codecs" title="codecs: Encode and decode data and streams."><code class="xref py py-mod docutils literal notranslate"><span class="pre">codecs</span></code></a> module for the list of supported encodings.</p> <p><em>errors</em> is an optional string that specifies how encoding and decoding errors are to be handled—this cannot be used in binary mode. A variety of standard error handlers are available (listed under <a class="reference internal" href="codecs.html#error-handlers"><span class="std std-ref">Error Handlers</span></a>), though any error handling name that has been registered with <a class="reference internal" href="codecs.html#codecs.register_error" title="codecs.register_error"><code class="xref py py-func docutils literal notranslate"><span class="pre">codecs.register_error()</span></code></a> is also valid. The standard names include:</p> <ul class="simple"> <li><p><code class="docutils literal notranslate"><span class="pre">'strict'</span></code> to raise a <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> exception if there is an encoding error. The default value of <code class="docutils literal notranslate"><span class="pre">None</span></code> has the same effect.</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">'ignore'</span></code> ignores errors. Note that ignoring encoding errors can lead to data loss.</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">'replace'</span></code> causes a replacement marker (such as <code class="docutils literal notranslate"><span class="pre">'?'</span></code>) to be inserted where there is malformed data.</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">'surrogateescape'</span></code> will represent any incorrect bytes as code points in the Unicode Private Use Area ranging from U+DC80 to U+DCFF. These private code points will then be turned back into the same bytes when the <code class="docutils literal notranslate"><span class="pre">surrogateescape</span></code> error handler is used when writing data. This is useful for processing files in an unknown encoding.</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">'xmlcharrefreplace'</span></code> is only supported when writing to a file. Characters not supported by the encoding are replaced with the appropriate XML character reference <code class="docutils literal notranslate"><span class="pre">&#nnn;</span></code>.</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">'backslashreplace'</span></code> replaces malformed data by Python’s backslashed escape sequences.</p></li> <li><p><code class="docutils literal notranslate"><span class="pre">'namereplace'</span></code> (also only supported when writing) replaces unsupported characters with <code class="docutils literal notranslate"><span class="pre">\N{...}</span></code> escape sequences.</p></li> </ul> <p id="open-newline-parameter"><span id="index-6"></span><em>newline</em> controls how <a class="reference internal" href="../glossary.html#term-universal-newlines"><span class="xref std std-term">universal newlines</span></a> mode works (it only applies to text mode). It can be <code class="docutils literal notranslate"><span class="pre">None</span></code>, <code class="docutils literal notranslate"><span class="pre">''</span></code>, <code class="docutils literal notranslate"><span class="pre">'\n'</span></code>, <code class="docutils literal notranslate"><span class="pre">'\r'</span></code>, and <code class="docutils literal notranslate"><span class="pre">'\r\n'</span></code>. It works as follows:</p> <ul class="simple"> <li><p>When reading input from the stream, if <em>newline</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code>, universal newlines mode is enabled. Lines in the input can end in <code class="docutils literal notranslate"><span class="pre">'\n'</span></code>, <code class="docutils literal notranslate"><span class="pre">'\r'</span></code>, or <code class="docutils literal notranslate"><span class="pre">'\r\n'</span></code>, and these are translated into <code class="docutils literal notranslate"><span class="pre">'\n'</span></code> before being returned to the caller. If it is <code class="docutils literal notranslate"><span class="pre">''</span></code>, universal newlines mode is enabled, but line endings are returned to the caller untranslated. If it has any of the other legal values, input lines are only terminated by the given string, and the line ending is returned to the caller untranslated.</p></li> <li><p>When writing output to the stream, if <em>newline</em> is <code class="docutils literal notranslate"><span class="pre">None</span></code>, any <code class="docutils literal notranslate"><span class="pre">'\n'</span></code> characters written are translated to the system default line separator, <a class="reference internal" href="os.html#os.linesep" title="os.linesep"><code class="xref py py-data docutils literal notranslate"><span class="pre">os.linesep</span></code></a>. If <em>newline</em> is <code class="docutils literal notranslate"><span class="pre">''</span></code> or <code class="docutils literal notranslate"><span class="pre">'\n'</span></code>, no translation takes place. If <em>newline</em> is any of the other legal values, any <code class="docutils literal notranslate"><span class="pre">'\n'</span></code> characters written are translated to the given string.</p></li> </ul> <p>If <em>closefd</em> is <code class="docutils literal notranslate"><span class="pre">False</span></code> and a file descriptor rather than a filename was given, the underlying file descriptor will be kept open when the file is closed. If a filename is given <em>closefd</em> must be <code class="docutils literal notranslate"><span class="pre">True</span></code> (the default) otherwise an error will be raised.</p> <p>A custom opener can be used by passing a callable as <em>opener</em>. The underlying file descriptor for the file object is then obtained by calling <em>opener</em> with (<em>file</em>, <em>flags</em>). <em>opener</em> must return an open file descriptor (passing <a class="reference internal" href="os.html#os.open" title="os.open"><code class="xref py py-mod docutils literal notranslate"><span class="pre">os.open</span></code></a> as <em>opener</em> results in functionality similar to passing <code class="docutils literal notranslate"><span class="pre">None</span></code>).</p> <p>The newly created file is <a class="reference internal" href="os.html#fd-inheritance"><span class="std std-ref">non-inheritable</span></a>.</p> <p>The following example uses the <a class="reference internal" href="os.html#dir-fd"><span class="std std-ref">dir_fd</span></a> parameter of the <a class="reference internal" href="os.html#os.open" title="os.open"><code class="xref py py-func docutils literal notranslate"><span class="pre">os.open()</span></code></a> function to open a file relative to a given directory:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">os</span> <span class="gp">>>> </span><span class="n">dir_fd</span> <span class="o">=</span> <span class="n">os</span><span class="o">.</span><span class="n">open</span><span class="p">(</span><span class="s1">'somedir'</span><span class="p">,</span> <span class="n">os</span><span class="o">.</span><span class="n">O_RDONLY</span><span class="p">)</span> <span class="gp">>>> </span><span class="k">def</span> <span class="nf">opener</span><span class="p">(</span><span class="n">path</span><span class="p">,</span> <span class="n">flags</span><span class="p">):</span> <span class="gp">... </span> <span class="k">return</span> <span class="n">os</span><span class="o">.</span><span class="n">open</span><span class="p">(</span><span class="n">path</span><span class="p">,</span> <span class="n">flags</span><span class="p">,</span> <span class="n">dir_fd</span><span class="o">=</span><span class="n">dir_fd</span><span class="p">)</span> <span class="gp">...</span> <span class="gp">>>> </span><span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'spamspam.txt'</span><span class="p">,</span> <span class="s1">'w'</span><span class="p">,</span> <span class="n">opener</span><span class="o">=</span><span class="n">opener</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span> <span class="gp">... </span> <span class="nb">print</span><span class="p">(</span><span class="s1">'This will be written to somedir/spamspam.txt'</span><span class="p">,</span> <span class="n">file</span><span class="o">=</span><span class="n">f</span><span class="p">)</span> <span class="gp">...</span> <span class="gp">>>> </span><span class="n">os</span><span class="o">.</span><span class="n">close</span><span class="p">(</span><span class="n">dir_fd</span><span class="p">)</span> <span class="c1"># don't leak a file descriptor</span> </pre></div> </div> <p>The type of <a class="reference internal" href="../glossary.html#term-file-object"><span class="xref std std-term">file object</span></a> returned by the <a class="reference internal" href="#open" title="open"><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code></a> function depends on the mode. When <a class="reference internal" href="#open" title="open"><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code></a> is used to open a file in a text mode (<code class="docutils literal notranslate"><span class="pre">'w'</span></code>, <code class="docutils literal notranslate"><span class="pre">'r'</span></code>, <code class="docutils literal notranslate"><span class="pre">'wt'</span></code>, <code class="docutils literal notranslate"><span class="pre">'rt'</span></code>, etc.), it returns a subclass of <a class="reference internal" href="io.html#io.TextIOBase" title="io.TextIOBase"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.TextIOBase</span></code></a> (specifically <a class="reference internal" href="io.html#io.TextIOWrapper" title="io.TextIOWrapper"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.TextIOWrapper</span></code></a>). When used to open a file in a binary mode with buffering, the returned class is a subclass of <a class="reference internal" href="io.html#io.BufferedIOBase" title="io.BufferedIOBase"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.BufferedIOBase</span></code></a>. The exact class varies: in read binary mode, it returns an <a class="reference internal" href="io.html#io.BufferedReader" title="io.BufferedReader"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.BufferedReader</span></code></a>; in write binary and append binary modes, it returns an <a class="reference internal" href="io.html#io.BufferedWriter" title="io.BufferedWriter"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.BufferedWriter</span></code></a>, and in read/write mode, it returns an <a class="reference internal" href="io.html#io.BufferedRandom" title="io.BufferedRandom"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.BufferedRandom</span></code></a>. When buffering is disabled, the raw stream, a subclass of <a class="reference internal" href="io.html#io.RawIOBase" title="io.RawIOBase"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.RawIOBase</span></code></a>, <a class="reference internal" href="io.html#io.FileIO" title="io.FileIO"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.FileIO</span></code></a>, is returned.</p> <p id="index-7">See also the file handling modules, such as, <a class="reference internal" href="fileinput.html#module-fileinput" title="fileinput: Loop over standard input or a list of files."><code class="xref py py-mod docutils literal notranslate"><span class="pre">fileinput</span></code></a>, <a class="reference internal" href="io.html#module-io" title="io: Core tools for working with streams."><code class="xref py py-mod docutils literal notranslate"><span class="pre">io</span></code></a> (where <a class="reference internal" href="#open" title="open"><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code></a> is declared), <a class="reference internal" href="os.html#module-os" title="os: Miscellaneous operating system interfaces."><code class="xref py py-mod docutils literal notranslate"><span class="pre">os</span></code></a>, <a class="reference internal" href="os.path.html#module-os.path" title="os.path: Operations on pathnames."><code class="xref py py-mod docutils literal notranslate"><span class="pre">os.path</span></code></a>, <a class="reference internal" href="tempfile.html#module-tempfile" title="tempfile: Generate temporary files and directories."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tempfile</span></code></a>, and <a class="reference internal" href="shutil.html#module-shutil" title="shutil: High-level file operations, including copying."><code class="xref py py-mod docutils literal notranslate"><span class="pre">shutil</span></code></a>.</p> <div class="versionchanged"> <blockquote> <div><span class="versionmodified changed">Changed in version 3.3: </span><ul class="simple"> <li><p>The <em>opener</em> parameter was added.</p></li> <li><p>The <code class="docutils literal notranslate"><span class="pre">'x'</span></code> mode was added.</p></li> <li><p><a class="reference internal" href="exceptions.html#IOError" title="IOError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">IOError</span></code></a> used to be raised, it is now an alias of <a class="reference internal" href="exceptions.html#OSError" title="OSError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OSError</span></code></a>.</p></li> <li><p><a class="reference internal" href="exceptions.html#FileExistsError" title="FileExistsError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">FileExistsError</span></code></a> is now raised if the file opened in exclusive creation mode (<code class="docutils literal notranslate"><span class="pre">'x'</span></code>) already exists.</p></li> </ul> </div></blockquote> </div> <div class="versionchanged"> <blockquote> <div><span class="versionmodified changed">Changed in version 3.4: </span><ul class="simple"> <li><p>The file is now non-inheritable.</p></li> </ul> </div></blockquote> </div> <div class="deprecated"> <p><span class="versionmodified">Deprecated since version 3.4, will be removed in version 4.0: </span>The <code class="docutils literal notranslate"><span class="pre">'U'</span></code> mode.</p> </div> <div class="versionchanged"> <blockquote> <div><span class="versionmodified changed">Changed in version 3.5: </span><ul class="simple"> <li><p>If the system call is interrupted and the signal handler does not raise an exception, the function now retries the system call instead of raising an <a class="reference internal" href="exceptions.html#InterruptedError" title="InterruptedError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">InterruptedError</span></code></a> exception (see <span class="target" id="index-8"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0475"><strong>PEP 475</strong></a> for the rationale).</p></li> <li><p>The <code class="docutils literal notranslate"><span class="pre">'namereplace'</span></code> error handler was added.</p></li> </ul> </div></blockquote> </div> <div class="versionchanged"> <blockquote> <div><span class="versionmodified changed">Changed in version 3.6: </span><ul class="simple"> <li><p>Support added to accept objects implementing <a class="reference internal" href="os.html#os.PathLike" title="os.PathLike"><code class="xref py py-class docutils literal notranslate"><span class="pre">os.PathLike</span></code></a>.</p></li> <li><p>On Windows, opening a console buffer may return a subclass of <a class="reference internal" href="io.html#io.RawIOBase" title="io.RawIOBase"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.RawIOBase</span></code></a> other than <a class="reference internal" href="io.html#io.FileIO" title="io.FileIO"><code class="xref py py-class docutils literal notranslate"><span class="pre">io.FileIO</span></code></a>.</p></li> </ul> </div></blockquote> </div> </dd></dl> <dl class="function"> <dt id="ord"> <code class="descname">ord</code><span class="sig-paren">(</span><em>c</em><span class="sig-paren">)</span><a class="headerlink" href="#ord" title="Permalink to this definition">¶</a></dt> <dd><p>Given a string representing one Unicode character, return an integer representing the Unicode code point of that character. For example, <code class="docutils literal notranslate"><span class="pre">ord('a')</span></code> returns the integer <code class="docutils literal notranslate"><span class="pre">97</span></code> and <code class="docutils literal notranslate"><span class="pre">ord('€')</span></code> (Euro sign) returns <code class="docutils literal notranslate"><span class="pre">8364</span></code>. This is the inverse of <a class="reference internal" href="#chr" title="chr"><code class="xref py py-func docutils literal notranslate"><span class="pre">chr()</span></code></a>.</p> </dd></dl> <dl class="function"> <dt id="pow"> <code class="descname">pow</code><span class="sig-paren">(</span><em>x</em>, <em>y</em><span class="optional">[</span>, <em>z</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pow" title="Permalink to this definition">¶</a></dt> <dd><p>Return <em>x</em> to the power <em>y</em>; if <em>z</em> is present, return <em>x</em> to the power <em>y</em>, modulo <em>z</em> (computed more efficiently than <code class="docutils literal notranslate"><span class="pre">pow(x,</span> <span class="pre">y)</span> <span class="pre">%</span> <span class="pre">z</span></code>). The two-argument form <code class="docutils literal notranslate"><span class="pre">pow(x,</span> <span class="pre">y)</span></code> is equivalent to using the power operator: <code class="docutils literal notranslate"><span class="pre">x**y</span></code>.</p> <p>The arguments must have numeric types. With mixed operand types, the coercion rules for binary arithmetic operators apply. For <a class="reference internal" href="#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a> operands, the result has the same type as the operands (after coercion) unless the second argument is negative; in that case, all arguments are converted to float and a float result is delivered. For example, <code class="docutils literal notranslate"><span class="pre">10**2</span></code> returns <code class="docutils literal notranslate"><span class="pre">100</span></code>, but <code class="docutils literal notranslate"><span class="pre">10**-2</span></code> returns <code class="docutils literal notranslate"><span class="pre">0.01</span></code>. If the second argument is negative, the third argument must be omitted. If <em>z</em> is present, <em>x</em> and <em>y</em> must be of integer types, and <em>y</em> must be non-negative.</p> </dd></dl> <dl class="function"> <dt id="print"> <code class="descname">print</code><span class="sig-paren">(</span><em>*objects</em>, <em>sep=' '</em>, <em>end='\n'</em>, <em>file=sys.stdout</em>, <em>flush=False</em><span class="sig-paren">)</span><a class="headerlink" href="#print" title="Permalink to this definition">¶</a></dt> <dd><p>Print <em>objects</em> to the text stream <em>file</em>, separated by <em>sep</em> and followed by <em>end</em>. <em>sep</em>, <em>end</em>, <em>file</em> and <em>flush</em>, if present, must be given as keyword arguments.</p> <p>All non-keyword arguments are converted to strings like <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-func docutils literal notranslate"><span class="pre">str()</span></code></a> does and written to the stream, separated by <em>sep</em> and followed by <em>end</em>. Both <em>sep</em> and <em>end</em> must be strings; they can also be <code class="docutils literal notranslate"><span class="pre">None</span></code>, which means to use the default values. If no <em>objects</em> are given, <a class="reference internal" href="#print" title="print"><code class="xref py py-func docutils literal notranslate"><span class="pre">print()</span></code></a> will just write <em>end</em>.</p> <p>The <em>file</em> argument must be an object with a <code class="docutils literal notranslate"><span class="pre">write(string)</span></code> method; if it is not present or <code class="docutils literal notranslate"><span class="pre">None</span></code>, <a class="reference internal" href="sys.html#sys.stdout" title="sys.stdout"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.stdout</span></code></a> will be used. Since printed arguments are converted to text strings, <a class="reference internal" href="#print" title="print"><code class="xref py py-func docutils literal notranslate"><span class="pre">print()</span></code></a> cannot be used with binary mode file objects. For these, use <code class="docutils literal notranslate"><span class="pre">file.write(...)</span></code> instead.</p> <p>Whether output is buffered is usually determined by <em>file</em>, but if the <em>flush</em> keyword argument is true, the stream is forcibly flushed.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.3: </span>Added the <em>flush</em> keyword argument.</p> </div> </dd></dl> <dl class="class"> <dt id="property"> <em class="property">class </em><code class="descname">property</code><span class="sig-paren">(</span><em>fget=None</em>, <em>fset=None</em>, <em>fdel=None</em>, <em>doc=None</em><span class="sig-paren">)</span><a class="headerlink" href="#property" title="Permalink to this definition">¶</a></dt> <dd><p>Return a property attribute.</p> <p><em>fget</em> is a function for getting an attribute value. <em>fset</em> is a function for setting an attribute value. <em>fdel</em> is a function for deleting an attribute value. And <em>doc</em> creates a docstring for the attribute.</p> <p>A typical use is to define a managed attribute <code class="docutils literal notranslate"><span class="pre">x</span></code>:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">C</span><span class="p">:</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">_x</span> <span class="o">=</span> <span class="kc">None</span> <span class="k">def</span> <span class="nf">getx</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_x</span> <span class="k">def</span> <span class="nf">setx</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">value</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">_x</span> <span class="o">=</span> <span class="n">value</span> <span class="k">def</span> <span class="nf">delx</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="k">del</span> <span class="bp">self</span><span class="o">.</span><span class="n">_x</span> <span class="n">x</span> <span class="o">=</span> <span class="nb">property</span><span class="p">(</span><span class="n">getx</span><span class="p">,</span> <span class="n">setx</span><span class="p">,</span> <span class="n">delx</span><span class="p">,</span> <span class="s2">"I'm the 'x' property."</span><span class="p">)</span> </pre></div> </div> <p>If <em>c</em> is an instance of <em>C</em>, <code class="docutils literal notranslate"><span class="pre">c.x</span></code> will invoke the getter, <code class="docutils literal notranslate"><span class="pre">c.x</span> <span class="pre">=</span> <span class="pre">value</span></code> will invoke the setter and <code class="docutils literal notranslate"><span class="pre">del</span> <span class="pre">c.x</span></code> the deleter.</p> <p>If given, <em>doc</em> will be the docstring of the property attribute. Otherwise, the property will copy <em>fget</em>’s docstring (if it exists). This makes it possible to create read-only properties easily using <a class="reference internal" href="#property" title="property"><code class="xref py py-func docutils literal notranslate"><span class="pre">property()</span></code></a> as a <a class="reference internal" href="../glossary.html#term-decorator"><span class="xref std std-term">decorator</span></a>:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Parrot</span><span class="p">:</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">_voltage</span> <span class="o">=</span> <span class="mi">100000</span> <span class="nd">@property</span> <span class="k">def</span> <span class="nf">voltage</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="sd">"""Get the current voltage."""</span> <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_voltage</span> </pre></div> </div> <p>The <code class="docutils literal notranslate"><span class="pre">@property</span></code> decorator turns the <code class="xref py py-meth docutils literal notranslate"><span class="pre">voltage()</span></code> method into a “getter” for a read-only attribute with the same name, and it sets the docstring for <em>voltage</em> to “Get the current voltage.”</p> <p>A property object has <code class="xref py py-attr docutils literal notranslate"><span class="pre">getter</span></code>, <code class="xref py py-attr docutils literal notranslate"><span class="pre">setter</span></code>, and <code class="xref py py-attr docutils literal notranslate"><span class="pre">deleter</span></code> methods usable as decorators that create a copy of the property with the corresponding accessor function set to the decorated function. This is best explained with an example:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">C</span><span class="p">:</span> <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">_x</span> <span class="o">=</span> <span class="kc">None</span> <span class="nd">@property</span> <span class="k">def</span> <span class="nf">x</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="sd">"""I'm the 'x' property."""</span> <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_x</span> <span class="nd">@x</span><span class="o">.</span><span class="n">setter</span> <span class="k">def</span> <span class="nf">x</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">value</span><span class="p">):</span> <span class="bp">self</span><span class="o">.</span><span class="n">_x</span> <span class="o">=</span> <span class="n">value</span> <span class="nd">@x</span><span class="o">.</span><span class="n">deleter</span> <span class="k">def</span> <span class="nf">x</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="k">del</span> <span class="bp">self</span><span class="o">.</span><span class="n">_x</span> </pre></div> </div> <p>This code is exactly equivalent to the first example. Be sure to give the additional functions the same name as the original property (<code class="docutils literal notranslate"><span class="pre">x</span></code> in this case.)</p> <p>The returned property object also has the attributes <code class="docutils literal notranslate"><span class="pre">fget</span></code>, <code class="docutils literal notranslate"><span class="pre">fset</span></code>, and <code class="docutils literal notranslate"><span class="pre">fdel</span></code> corresponding to the constructor arguments.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.5: </span>The docstrings of property objects are now writeable.</p> </div> </dd></dl> <span class="target" id="func-range"></span><dl class="function"> <dt> <code class="descname">range</code><span class="sig-paren">(</span><em>stop</em><span class="sig-paren">)</span></dt> <dt> <code class="descname">range</code><span class="sig-paren">(</span><em>start</em>, <em>stop</em><span class="optional">[</span>, <em>step</em><span class="optional">]</span><span class="sig-paren">)</span></dt> <dd><p>Rather than being a function, <a class="reference internal" href="stdtypes.html#range" title="range"><code class="xref py py-class docutils literal notranslate"><span class="pre">range</span></code></a> is actually an immutable sequence type, as documented in <a class="reference internal" href="stdtypes.html#typesseq-range"><span class="std std-ref">Ranges</span></a> and <a class="reference internal" href="stdtypes.html#typesseq"><span class="std std-ref">Sequence Types — list, tuple, range</span></a>.</p> </dd></dl> <dl class="function"> <dt id="repr"> <code class="descname">repr</code><span class="sig-paren">(</span><em>object</em><span class="sig-paren">)</span><a class="headerlink" href="#repr" title="Permalink to this definition">¶</a></dt> <dd><p>Return a string containing a printable representation of an object. For many types, this function makes an attempt to return a string that would yield an object with the same value when passed to <a class="reference internal" href="#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a>, otherwise the representation is a string enclosed in angle brackets that contains the name of the type of the object together with additional information often including the name and address of the object. A class can control what this function returns for its instances by defining a <a class="reference internal" href="../reference/datamodel.html#object.__repr__" title="object.__repr__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__repr__()</span></code></a> method.</p> </dd></dl> <dl class="function"> <dt id="reversed"> <code class="descname">reversed</code><span class="sig-paren">(</span><em>seq</em><span class="sig-paren">)</span><a class="headerlink" href="#reversed" title="Permalink to this definition">¶</a></dt> <dd><p>Return a reverse <a class="reference internal" href="../glossary.html#term-iterator"><span class="xref std std-term">iterator</span></a>. <em>seq</em> must be an object which has a <a class="reference internal" href="../reference/datamodel.html#object.__reversed__" title="object.__reversed__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__reversed__()</span></code></a> method or supports the sequence protocol (the <a class="reference internal" href="../reference/datamodel.html#object.__len__" title="object.__len__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__len__()</span></code></a> method and the <a class="reference internal" href="../reference/datamodel.html#object.__getitem__" title="object.__getitem__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__getitem__()</span></code></a> method with integer arguments starting at <code class="docutils literal notranslate"><span class="pre">0</span></code>).</p> </dd></dl> <dl class="function"> <dt id="round"> <code class="descname">round</code><span class="sig-paren">(</span><em>number</em><span class="optional">[</span>, <em>ndigits</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#round" title="Permalink to this definition">¶</a></dt> <dd><p>Return <em>number</em> rounded to <em>ndigits</em> precision after the decimal point. If <em>ndigits</em> is omitted or is <code class="docutils literal notranslate"><span class="pre">None</span></code>, it returns the nearest integer to its input.</p> <p>For the built-in types supporting <a class="reference internal" href="#round" title="round"><code class="xref py py-func docutils literal notranslate"><span class="pre">round()</span></code></a>, values are rounded to the closest multiple of 10 to the power minus <em>ndigits</em>; if two multiples are equally close, rounding is done toward the even choice (so, for example, both <code class="docutils literal notranslate"><span class="pre">round(0.5)</span></code> and <code class="docutils literal notranslate"><span class="pre">round(-0.5)</span></code> are <code class="docutils literal notranslate"><span class="pre">0</span></code>, and <code class="docutils literal notranslate"><span class="pre">round(1.5)</span></code> is <code class="docutils literal notranslate"><span class="pre">2</span></code>). Any integer value is valid for <em>ndigits</em> (positive, zero, or negative). The return value is an integer if <em>ndigits</em> is omitted or <code class="docutils literal notranslate"><span class="pre">None</span></code>. Otherwise the return value has the same type as <em>number</em>.</p> <p>For a general Python object <code class="docutils literal notranslate"><span class="pre">number</span></code>, <code class="docutils literal notranslate"><span class="pre">round</span></code> delegates to <code class="docutils literal notranslate"><span class="pre">number.__round__</span></code>.</p> <div class="admonition note"> <p class="admonition-title">Note</p> <p>The behavior of <a class="reference internal" href="#round" title="round"><code class="xref py py-func docutils literal notranslate"><span class="pre">round()</span></code></a> for floats can be surprising: for example, <code class="docutils literal notranslate"><span class="pre">round(2.675,</span> <span class="pre">2)</span></code> gives <code class="docutils literal notranslate"><span class="pre">2.67</span></code> instead of the expected <code class="docutils literal notranslate"><span class="pre">2.68</span></code>. This is not a bug: it’s a result of the fact that most decimal fractions can’t be represented exactly as a float. See <a class="reference internal" href="../tutorial/floatingpoint.html#tut-fp-issues"><span class="std std-ref">Floating Point Arithmetic: Issues and Limitations</span></a> for more information.</p> </div> </dd></dl> <span class="target" id="func-set"></span><dl class="class"> <dt> <em class="property">class </em><code class="descname">set</code><span class="sig-paren">(</span><span class="optional">[</span><em>iterable</em><span class="optional">]</span><span class="sig-paren">)</span></dt> <dd><p>Return a new <a class="reference internal" href="stdtypes.html#set" title="set"><code class="xref py py-class docutils literal notranslate"><span class="pre">set</span></code></a> object, optionally with elements taken from <em>iterable</em>. <code class="docutils literal notranslate"><span class="pre">set</span></code> is a built-in class. See <a class="reference internal" href="stdtypes.html#set" title="set"><code class="xref py py-class docutils literal notranslate"><span class="pre">set</span></code></a> and <a class="reference internal" href="stdtypes.html#types-set"><span class="std std-ref">Set Types — set, frozenset</span></a> for documentation about this class.</p> <p>For other containers see the built-in <a class="reference internal" href="stdtypes.html#frozenset" title="frozenset"><code class="xref py py-class docutils literal notranslate"><span class="pre">frozenset</span></code></a>, <a class="reference internal" href="stdtypes.html#list" title="list"><code class="xref py py-class docutils literal notranslate"><span class="pre">list</span></code></a>, <a class="reference internal" href="stdtypes.html#tuple" title="tuple"><code class="xref py py-class docutils literal notranslate"><span class="pre">tuple</span></code></a>, and <a class="reference internal" href="stdtypes.html#dict" title="dict"><code class="xref py py-class docutils literal notranslate"><span class="pre">dict</span></code></a> classes, as well as the <a class="reference internal" href="collections.html#module-collections" title="collections: Container datatypes"><code class="xref py py-mod docutils literal notranslate"><span class="pre">collections</span></code></a> module.</p> </dd></dl> <dl class="function"> <dt id="setattr"> <code class="descname">setattr</code><span class="sig-paren">(</span><em>object</em>, <em>name</em>, <em>value</em><span class="sig-paren">)</span><a class="headerlink" href="#setattr" title="Permalink to this definition">¶</a></dt> <dd><p>This is the counterpart of <a class="reference internal" href="#getattr" title="getattr"><code class="xref py py-func docutils literal notranslate"><span class="pre">getattr()</span></code></a>. The arguments are an object, a string and an arbitrary value. The string may name an existing attribute or a new attribute. The function assigns the value to the attribute, provided the object allows it. For example, <code class="docutils literal notranslate"><span class="pre">setattr(x,</span> <span class="pre">'foobar',</span> <span class="pre">123)</span></code> is equivalent to <code class="docutils literal notranslate"><span class="pre">x.foobar</span> <span class="pre">=</span> <span class="pre">123</span></code>.</p> </dd></dl> <dl class="class"> <dt id="slice"> <em class="property">class </em><code class="descname">slice</code><span class="sig-paren">(</span><em>stop</em><span class="sig-paren">)</span><a class="headerlink" href="#slice" title="Permalink to this definition">¶</a></dt> <dt> <em class="property">class </em><code class="descname">slice</code><span class="sig-paren">(</span><em>start</em>, <em>stop</em><span class="optional">[</span>, <em>step</em><span class="optional">]</span><span class="sig-paren">)</span></dt> <dd><p id="index-9">Return a <a class="reference internal" href="../glossary.html#term-slice"><span class="xref std std-term">slice</span></a> object representing the set of indices specified by <code class="docutils literal notranslate"><span class="pre">range(start,</span> <span class="pre">stop,</span> <span class="pre">step)</span></code>. The <em>start</em> and <em>step</em> arguments default to <code class="docutils literal notranslate"><span class="pre">None</span></code>. Slice objects have read-only data attributes <code class="xref py py-attr docutils literal notranslate"><span class="pre">start</span></code>, <code class="xref py py-attr docutils literal notranslate"><span class="pre">stop</span></code> and <code class="xref py py-attr docutils literal notranslate"><span class="pre">step</span></code> which merely return the argument values (or their default). They have no other explicit functionality; however they are used by Numerical Python and other third party extensions. Slice objects are also generated when extended indexing syntax is used. For example: <code class="docutils literal notranslate"><span class="pre">a[start:stop:step]</span></code> or <code class="docutils literal notranslate"><span class="pre">a[start:stop,</span> <span class="pre">i]</span></code>. See <a class="reference internal" href="itertools.html#itertools.islice" title="itertools.islice"><code class="xref py py-func docutils literal notranslate"><span class="pre">itertools.islice()</span></code></a> for an alternate version that returns an iterator.</p> </dd></dl> <dl class="function"> <dt id="sorted"> <code class="descname">sorted</code><span class="sig-paren">(</span><em>iterable</em>, <em>*</em>, <em>key=None</em>, <em>reverse=False</em><span class="sig-paren">)</span><a class="headerlink" href="#sorted" title="Permalink to this definition">¶</a></dt> <dd><p>Return a new sorted list from the items in <em>iterable</em>.</p> <p>Has two optional arguments which must be specified as keyword arguments.</p> <p><em>key</em> specifies a function of one argument that is used to extract a comparison key from each element in <em>iterable</em> (for example, <code class="docutils literal notranslate"><span class="pre">key=str.lower</span></code>). The default value is <code class="docutils literal notranslate"><span class="pre">None</span></code> (compare the elements directly).</p> <p><em>reverse</em> is a boolean value. If set to <code class="docutils literal notranslate"><span class="pre">True</span></code>, then the list elements are sorted as if each comparison were reversed.</p> <p>Use <a class="reference internal" href="functools.html#functools.cmp_to_key" title="functools.cmp_to_key"><code class="xref py py-func docutils literal notranslate"><span class="pre">functools.cmp_to_key()</span></code></a> to convert an old-style <em>cmp</em> function to a <em>key</em> function.</p> <p>The built-in <a class="reference internal" href="#sorted" title="sorted"><code class="xref py py-func docutils literal notranslate"><span class="pre">sorted()</span></code></a> function is guaranteed to be stable. A sort is stable if it guarantees not to change the relative order of elements that compare equal — this is helpful for sorting in multiple passes (for example, sort by department, then by salary grade).</p> <p>For sorting examples and a brief sorting tutorial, see <a class="reference internal" href="../howto/sorting.html#sortinghowto"><span class="std std-ref">Sorting HOW TO</span></a>.</p> </dd></dl> <dl class="function"> <dt id="staticmethod"> <code class="descclassname">@</code><code class="descname">staticmethod</code><a class="headerlink" href="#staticmethod" title="Permalink to this definition">¶</a></dt> <dd><p>Transform a method into a static method.</p> <p>A static method does not receive an implicit first argument. To declare a static method, use this idiom:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">C</span><span class="p">:</span> <span class="nd">@staticmethod</span> <span class="k">def</span> <span class="nf">f</span><span class="p">(</span><span class="n">arg1</span><span class="p">,</span> <span class="n">arg2</span><span class="p">,</span> <span class="o">...</span><span class="p">):</span> <span class="o">...</span> </pre></div> </div> <p>The <code class="docutils literal notranslate"><span class="pre">@staticmethod</span></code> form is a function <a class="reference internal" href="../glossary.html#term-decorator"><span class="xref std std-term">decorator</span></a> – see <a class="reference internal" href="../reference/compound_stmts.html#function"><span class="std std-ref">Function definitions</span></a> for details.</p> <p>A static method can be called either on the class (such as <code class="docutils literal notranslate"><span class="pre">C.f()</span></code>) or on an instance (such as <code class="docutils literal notranslate"><span class="pre">C().f()</span></code>).</p> <p>Static methods in Python are similar to those found in Java or C++. Also see <a class="reference internal" href="#classmethod" title="classmethod"><code class="xref py py-func docutils literal notranslate"><span class="pre">classmethod()</span></code></a> for a variant that is useful for creating alternate class constructors.</p> <p>Like all decorators, it is also possible to call <code class="docutils literal notranslate"><span class="pre">staticmethod</span></code> as a regular function and do something with its result. This is needed in some cases where you need a reference to a function from a class body and you want to avoid the automatic transformation to instance method. For these cases, use this idiom:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">C</span><span class="p">:</span> <span class="n">builtin_open</span> <span class="o">=</span> <span class="nb">staticmethod</span><span class="p">(</span><span class="nb">open</span><span class="p">)</span> </pre></div> </div> <p>For more information on static methods, see <a class="reference internal" href="../reference/datamodel.html#types"><span class="std std-ref">The standard type hierarchy</span></a>.</p> </dd></dl> <span class="target" id="func-str"><span id="index-10"></span></span><dl class="class"> <dt> <em class="property">class </em><code class="descname">str</code><span class="sig-paren">(</span><em>object=''</em><span class="sig-paren">)</span></dt> <dt> <em class="property">class </em><code class="descname">str</code><span class="sig-paren">(</span><em>object=b''</em>, <em>encoding='utf-8'</em>, <em>errors='strict'</em><span class="sig-paren">)</span></dt> <dd><p>Return a <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code></a> version of <em>object</em>. See <a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-func docutils literal notranslate"><span class="pre">str()</span></code></a> for details.</p> <p><code class="docutils literal notranslate"><span class="pre">str</span></code> is the built-in string <a class="reference internal" href="../glossary.html#term-class"><span class="xref std std-term">class</span></a>. For general information about strings, see <a class="reference internal" href="stdtypes.html#textseq"><span class="std std-ref">Text Sequence Type — str</span></a>.</p> </dd></dl> <dl class="function"> <dt id="sum"> <code class="descname">sum</code><span class="sig-paren">(</span><em>iterable</em><span class="optional">[</span>, <em>start</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#sum" title="Permalink to this definition">¶</a></dt> <dd><p>Sums <em>start</em> and the items of an <em>iterable</em> from left to right and returns the total. <em>start</em> defaults to <code class="docutils literal notranslate"><span class="pre">0</span></code>. The <em>iterable</em>’s items are normally numbers, and the start value is not allowed to be a string.</p> <p>For some use cases, there are good alternatives to <a class="reference internal" href="#sum" title="sum"><code class="xref py py-func docutils literal notranslate"><span class="pre">sum()</span></code></a>. The preferred, fast way to concatenate a sequence of strings is by calling <code class="docutils literal notranslate"><span class="pre">''.join(sequence)</span></code>. To add floating point values with extended precision, see <a class="reference internal" href="math.html#math.fsum" title="math.fsum"><code class="xref py py-func docutils literal notranslate"><span class="pre">math.fsum()</span></code></a>. To concatenate a series of iterables, consider using <a class="reference internal" href="itertools.html#itertools.chain" title="itertools.chain"><code class="xref py py-func docutils literal notranslate"><span class="pre">itertools.chain()</span></code></a>.</p> </dd></dl> <dl class="function"> <dt id="super"> <code class="descname">super</code><span class="sig-paren">(</span><span class="optional">[</span><em>type</em><span class="optional">[</span>, <em>object-or-type</em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#super" title="Permalink to this definition">¶</a></dt> <dd><p>Return a proxy object that delegates method calls to a parent or sibling class of <em>type</em>. This is useful for accessing inherited methods that have been overridden in a class. The search order is same as that used by <a class="reference internal" href="#getattr" title="getattr"><code class="xref py py-func docutils literal notranslate"><span class="pre">getattr()</span></code></a> except that the <em>type</em> itself is skipped.</p> <p>The <a class="reference internal" href="stdtypes.html#class.__mro__" title="class.__mro__"><code class="xref py py-attr docutils literal notranslate"><span class="pre">__mro__</span></code></a> attribute of the <em>type</em> lists the method resolution search order used by both <a class="reference internal" href="#getattr" title="getattr"><code class="xref py py-func docutils literal notranslate"><span class="pre">getattr()</span></code></a> and <a class="reference internal" href="#super" title="super"><code class="xref py py-func docutils literal notranslate"><span class="pre">super()</span></code></a>. The attribute is dynamic and can change whenever the inheritance hierarchy is updated.</p> <p>If the second argument is omitted, the super object returned is unbound. If the second argument is an object, <code class="docutils literal notranslate"><span class="pre">isinstance(obj,</span> <span class="pre">type)</span></code> must be true. If the second argument is a type, <code class="docutils literal notranslate"><span class="pre">issubclass(type2,</span> <span class="pre">type)</span></code> must be true (this is useful for classmethods).</p> <p>There are two typical use cases for <em>super</em>. In a class hierarchy with single inheritance, <em>super</em> can be used to refer to parent classes without naming them explicitly, thus making the code more maintainable. This use closely parallels the use of <em>super</em> in other programming languages.</p> <p>The second use case is to support cooperative multiple inheritance in a dynamic execution environment. This use case is unique to Python and is not found in statically compiled languages or languages that only support single inheritance. This makes it possible to implement “diamond diagrams” where multiple base classes implement the same method. Good design dictates that this method have the same calling signature in every case (because the order of calls is determined at runtime, because that order adapts to changes in the class hierarchy, and because that order can include sibling classes that are unknown prior to runtime).</p> <p>For both use cases, a typical superclass call looks like this:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">C</span><span class="p">(</span><span class="n">B</span><span class="p">):</span> <span class="k">def</span> <span class="nf">method</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="nb">super</span><span class="p">()</span><span class="o">.</span><span class="n">method</span><span class="p">(</span><span class="n">arg</span><span class="p">)</span> <span class="c1"># This does the same thing as:</span> <span class="c1"># super(C, self).method(arg)</span> </pre></div> </div> <p>Note that <a class="reference internal" href="#super" title="super"><code class="xref py py-func docutils literal notranslate"><span class="pre">super()</span></code></a> is implemented as part of the binding process for explicit dotted attribute lookups such as <code class="docutils literal notranslate"><span class="pre">super().__getitem__(name)</span></code>. It does so by implementing its own <a class="reference internal" href="../reference/datamodel.html#object.__getattribute__" title="object.__getattribute__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__getattribute__()</span></code></a> method for searching classes in a predictable order that supports cooperative multiple inheritance. Accordingly, <a class="reference internal" href="#super" title="super"><code class="xref py py-func docutils literal notranslate"><span class="pre">super()</span></code></a> is undefined for implicit lookups using statements or operators such as <code class="docutils literal notranslate"><span class="pre">super()[name]</span></code>.</p> <p>Also note that, aside from the zero argument form, <a class="reference internal" href="#super" title="super"><code class="xref py py-func docutils literal notranslate"><span class="pre">super()</span></code></a> is not limited to use inside methods. The two argument form specifies the arguments exactly and makes the appropriate references. The zero argument form only works inside a class definition, as the compiler fills in the necessary details to correctly retrieve the class being defined, as well as accessing the current instance for ordinary methods.</p> <p>For practical suggestions on how to design cooperative classes using <a class="reference internal" href="#super" title="super"><code class="xref py py-func docutils literal notranslate"><span class="pre">super()</span></code></a>, see <a class="reference external" href="https://rhettinger.wordpress.com/2011/05/26/super-considered-super/">guide to using super()</a>.</p> </dd></dl> <span class="target" id="func-tuple"></span><dl class="function"> <dt> <code class="descname">tuple</code><span class="sig-paren">(</span><span class="optional">[</span><em>iterable</em><span class="optional">]</span><span class="sig-paren">)</span></dt> <dd><p>Rather than being a function, <a class="reference internal" href="stdtypes.html#tuple" title="tuple"><code class="xref py py-class docutils literal notranslate"><span class="pre">tuple</span></code></a> is actually an immutable sequence type, as documented in <a class="reference internal" href="stdtypes.html#typesseq-tuple"><span class="std std-ref">Tuples</span></a> and <a class="reference internal" href="stdtypes.html#typesseq"><span class="std std-ref">Sequence Types — list, tuple, range</span></a>.</p> </dd></dl> <dl class="class"> <dt id="type"> <em class="property">class </em><code class="descname">type</code><span class="sig-paren">(</span><em>object</em><span class="sig-paren">)</span><a class="headerlink" href="#type" title="Permalink to this definition">¶</a></dt> <dt> <em class="property">class </em><code class="descname">type</code><span class="sig-paren">(</span><em>name</em>, <em>bases</em>, <em>dict</em><span class="sig-paren">)</span></dt> <dd><p id="index-11">With one argument, return the type of an <em>object</em>. The return value is a type object and generally the same object as returned by <a class="reference internal" href="stdtypes.html#instance.__class__" title="instance.__class__"><code class="xref py py-attr docutils literal notranslate"><span class="pre">object.__class__</span></code></a>.</p> <p>The <a class="reference internal" href="#isinstance" title="isinstance"><code class="xref py py-func docutils literal notranslate"><span class="pre">isinstance()</span></code></a> built-in function is recommended for testing the type of an object, because it takes subclasses into account.</p> <p>With three arguments, return a new type object. This is essentially a dynamic form of the <a class="reference internal" href="../reference/compound_stmts.html#class"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">class</span></code></a> statement. The <em>name</em> string is the class name and becomes the <a class="reference internal" href="stdtypes.html#definition.__name__" title="definition.__name__"><code class="xref py py-attr docutils literal notranslate"><span class="pre">__name__</span></code></a> attribute; the <em>bases</em> tuple itemizes the base classes and becomes the <a class="reference internal" href="stdtypes.html#class.__bases__" title="class.__bases__"><code class="xref py py-attr docutils literal notranslate"><span class="pre">__bases__</span></code></a> attribute; and the <em>dict</em> dictionary is the namespace containing definitions for class body and is copied to a standard dictionary to become the <a class="reference internal" href="stdtypes.html#object.__dict__" title="object.__dict__"><code class="xref py py-attr docutils literal notranslate"><span class="pre">__dict__</span></code></a> attribute. For example, the following two statements create identical <a class="reference internal" href="#type" title="type"><code class="xref py py-class docutils literal notranslate"><span class="pre">type</span></code></a> objects:</p> <div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="k">class</span> <span class="nc">X</span><span class="p">:</span> <span class="gp">... </span> <span class="n">a</span> <span class="o">=</span> <span class="mi">1</span> <span class="gp">...</span> <span class="gp">>>> </span><span class="n">X</span> <span class="o">=</span> <span class="nb">type</span><span class="p">(</span><span class="s1">'X'</span><span class="p">,</span> <span class="p">(</span><span class="nb">object</span><span class="p">,),</span> <span class="nb">dict</span><span class="p">(</span><span class="n">a</span><span class="o">=</span><span class="mi">1</span><span class="p">))</span> </pre></div> </div> <p>See also <a class="reference internal" href="stdtypes.html#bltin-type-objects"><span class="std std-ref">Type Objects</span></a>.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.6: </span>Subclasses of <a class="reference internal" href="#type" title="type"><code class="xref py py-class docutils literal notranslate"><span class="pre">type</span></code></a> which don’t override <code class="docutils literal notranslate"><span class="pre">type.__new__</span></code> may no longer use the one-argument form to get the type of an object.</p> </div> </dd></dl> <dl class="function"> <dt id="vars"> <code class="descname">vars</code><span class="sig-paren">(</span><span class="optional">[</span><em>object</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#vars" title="Permalink to this definition">¶</a></dt> <dd><p>Return the <a class="reference internal" href="stdtypes.html#object.__dict__" title="object.__dict__"><code class="xref py py-attr docutils literal notranslate"><span class="pre">__dict__</span></code></a> attribute for a module, class, instance, or any other object with a <a class="reference internal" href="stdtypes.html#object.__dict__" title="object.__dict__"><code class="xref py py-attr docutils literal notranslate"><span class="pre">__dict__</span></code></a> attribute.</p> <p>Objects such as modules and instances have an updateable <a class="reference internal" href="stdtypes.html#object.__dict__" title="object.__dict__"><code class="xref py py-attr docutils literal notranslate"><span class="pre">__dict__</span></code></a> attribute; however, other objects may have write restrictions on their <a class="reference internal" href="stdtypes.html#object.__dict__" title="object.__dict__"><code class="xref py py-attr docutils literal notranslate"><span class="pre">__dict__</span></code></a> attributes (for example, classes use a <a class="reference internal" href="types.html#types.MappingProxyType" title="types.MappingProxyType"><code class="xref py py-class docutils literal notranslate"><span class="pre">types.MappingProxyType</span></code></a> to prevent direct dictionary updates).</p> <p>Without an argument, <a class="reference internal" href="#vars" title="vars"><code class="xref py py-func docutils literal notranslate"><span class="pre">vars()</span></code></a> acts like <a class="reference internal" href="#locals" title="locals"><code class="xref py py-func docutils literal notranslate"><span class="pre">locals()</span></code></a>. Note, the locals dictionary is only useful for reads since updates to the locals dictionary are ignored.</p> </dd></dl> <dl class="function"> <dt id="zip"> <code class="descname">zip</code><span class="sig-paren">(</span><em>*iterables</em><span class="sig-paren">)</span><a class="headerlink" href="#zip" title="Permalink to this definition">¶</a></dt> <dd><p>Make an iterator that aggregates elements from each of the iterables.</p> <p>Returns an iterator of tuples, where the <em>i</em>-th tuple contains the <em>i</em>-th element from each of the argument sequences or iterables. The iterator stops when the shortest input iterable is exhausted. With a single iterable argument, it returns an iterator of 1-tuples. With no arguments, it returns an empty iterator. Equivalent to:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">zip</span><span class="p">(</span><span class="o">*</span><span class="n">iterables</span><span class="p">):</span> <span class="c1"># zip('ABCD', 'xy') --> Ax By</span> <span class="n">sentinel</span> <span class="o">=</span> <span class="nb">object</span><span class="p">()</span> <span class="n">iterators</span> <span class="o">=</span> <span class="p">[</span><span class="nb">iter</span><span class="p">(</span><span class="n">it</span><span class="p">)</span> <span class="k">for</span> <span class="n">it</span> <span class="ow">in</span> <span class="n">iterables</span><span class="p">]</span> <span class="k">while</span> <span class="n">iterators</span><span class="p">:</span> <span class="n">result</span> <span class="o">=</span> <span class="p">[]</span> <span class="k">for</span> <span class="n">it</span> <span class="ow">in</span> <span class="n">iterators</span><span class="p">:</span> <span class="n">elem</span> <span class="o">=</span> <span class="nb">next</span><span class="p">(</span><span class="n">it</span><span class="p">,</span> <span class="n">sentinel</span><span class="p">)</span> <span class="k">if</span> <span class="n">elem</span> <span class="ow">is</span> <span class="n">sentinel</span><span class="p">:</span> <span class="k">return</span> <span class="n">result</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">elem</span><span class="p">)</span> <span class="k">yield</span> <span class="nb">tuple</span><span class="p">(</span><span class="n">result</span><span class="p">)</span> </pre></div> </div> <p>The left-to-right evaluation order of the iterables is guaranteed. This makes possible an idiom for clustering a data series into n-length groups using <code class="docutils literal notranslate"><span class="pre">zip(*[iter(s)]*n)</span></code>. This repeats the <em>same</em> iterator <code class="docutils literal notranslate"><span class="pre">n</span></code> times so that each output tuple has the result of <code class="docutils literal notranslate"><span class="pre">n</span></code> calls to the iterator. This has the effect of dividing the input into n-length chunks.</p> <p><a class="reference internal" href="#zip" title="zip"><code class="xref py py-func docutils literal notranslate"><span class="pre">zip()</span></code></a> should only be used with unequal length inputs when you don’t care about trailing, unmatched values from the longer iterables. If those values are important, use <a class="reference internal" href="itertools.html#itertools.zip_longest" title="itertools.zip_longest"><code class="xref py py-func docutils literal notranslate"><span class="pre">itertools.zip_longest()</span></code></a> instead.</p> <p><a class="reference internal" href="#zip" title="zip"><code class="xref py py-func docutils literal notranslate"><span class="pre">zip()</span></code></a> in conjunction with the <code class="docutils literal notranslate"><span class="pre">*</span></code> operator can be used to unzip a list:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">x</span> <span class="o">=</span> <span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">]</span> <span class="gp">>>> </span><span class="n">y</span> <span class="o">=</span> <span class="p">[</span><span class="mi">4</span><span class="p">,</span> <span class="mi">5</span><span class="p">,</span> <span class="mi">6</span><span class="p">]</span> <span class="gp">>>> </span><span class="n">zipped</span> <span class="o">=</span> <span class="nb">zip</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">)</span> <span class="gp">>>> </span><span class="nb">list</span><span class="p">(</span><span class="n">zipped</span><span class="p">)</span> <span class="go">[(1, 4), (2, 5), (3, 6)]</span> <span class="gp">>>> </span><span class="n">x2</span><span class="p">,</span> <span class="n">y2</span> <span class="o">=</span> <span class="nb">zip</span><span class="p">(</span><span class="o">*</span><span class="nb">zip</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">))</span> <span class="gp">>>> </span><span class="n">x</span> <span class="o">==</span> <span class="nb">list</span><span class="p">(</span><span class="n">x2</span><span class="p">)</span> <span class="ow">and</span> <span class="n">y</span> <span class="o">==</span> <span class="nb">list</span><span class="p">(</span><span class="n">y2</span><span class="p">)</span> <span class="go">True</span> </pre></div> </div> </dd></dl> <dl class="function"> <dt id="__import__"> <code class="descname">__import__</code><span class="sig-paren">(</span><em>name</em>, <em>globals=None</em>, <em>locals=None</em>, <em>fromlist=()</em>, <em>level=0</em><span class="sig-paren">)</span><a class="headerlink" href="#__import__" title="Permalink to this definition">¶</a></dt> <dd><div class="admonition note" id="index-12"> <p class="admonition-title">Note</p> <p>This is an advanced function that is not needed in everyday Python programming, unlike <a class="reference internal" href="importlib.html#importlib.import_module" title="importlib.import_module"><code class="xref py py-func docutils literal notranslate"><span class="pre">importlib.import_module()</span></code></a>.</p> </div> <p>This function is invoked by the <a class="reference internal" href="../reference/simple_stmts.html#import"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">import</span></code></a> statement. It can be replaced (by importing the <a class="reference internal" href="builtins.html#module-builtins" title="builtins: The module that provides the built-in namespace."><code class="xref py py-mod docutils literal notranslate"><span class="pre">builtins</span></code></a> module and assigning to <code class="docutils literal notranslate"><span class="pre">builtins.__import__</span></code>) in order to change semantics of the <code class="xref std std-keyword docutils literal notranslate"><span class="pre">import</span></code> statement, but doing so is <strong>strongly</strong> discouraged as it is usually simpler to use import hooks (see <span class="target" id="index-13"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0302"><strong>PEP 302</strong></a>) to attain the same goals and does not cause issues with code which assumes the default import implementation is in use. Direct use of <a class="reference internal" href="#__import__" title="__import__"><code class="xref py py-func docutils literal notranslate"><span class="pre">__import__()</span></code></a> is also discouraged in favor of <a class="reference internal" href="importlib.html#importlib.import_module" title="importlib.import_module"><code class="xref py py-func docutils literal notranslate"><span class="pre">importlib.import_module()</span></code></a>.</p> <p>The function imports the module <em>name</em>, potentially using the given <em>globals</em> and <em>locals</em> to determine how to interpret the name in a package context. The <em>fromlist</em> gives the names of objects or submodules that should be imported from the module given by <em>name</em>. The standard implementation does not use its <em>locals</em> argument at all, and uses its <em>globals</em> only to determine the package context of the <a class="reference internal" href="../reference/simple_stmts.html#import"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">import</span></code></a> statement.</p> <p><em>level</em> specifies whether to use absolute or relative imports. <code class="docutils literal notranslate"><span class="pre">0</span></code> (the default) means only perform absolute imports. Positive values for <em>level</em> indicate the number of parent directories to search relative to the directory of the module calling <a class="reference internal" href="#__import__" title="__import__"><code class="xref py py-func docutils literal notranslate"><span class="pre">__import__()</span></code></a> (see <span class="target" id="index-14"></span><a class="pep reference external" href="https://www.python.org/dev/peps/pep-0328"><strong>PEP 328</strong></a> for the details).</p> <p>When the <em>name</em> variable is of the form <code class="docutils literal notranslate"><span class="pre">package.module</span></code>, normally, the top-level package (the name up till the first dot) is returned, <em>not</em> the module named by <em>name</em>. However, when a non-empty <em>fromlist</em> argument is given, the module named by <em>name</em> is returned.</p> <p>For example, the statement <code class="docutils literal notranslate"><span class="pre">import</span> <span class="pre">spam</span></code> results in bytecode resembling the following code:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">spam</span> <span class="o">=</span> <span class="nb">__import__</span><span class="p">(</span><span class="s1">'spam'</span><span class="p">,</span> <span class="nb">globals</span><span class="p">(),</span> <span class="nb">locals</span><span class="p">(),</span> <span class="p">[],</span> <span class="mi">0</span><span class="p">)</span> </pre></div> </div> <p>The statement <code class="docutils literal notranslate"><span class="pre">import</span> <span class="pre">spam.ham</span></code> results in this call:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">spam</span> <span class="o">=</span> <span class="nb">__import__</span><span class="p">(</span><span class="s1">'spam.ham'</span><span class="p">,</span> <span class="nb">globals</span><span class="p">(),</span> <span class="nb">locals</span><span class="p">(),</span> <span class="p">[],</span> <span class="mi">0</span><span class="p">)</span> </pre></div> </div> <p>Note how <a class="reference internal" href="#__import__" title="__import__"><code class="xref py py-func docutils literal notranslate"><span class="pre">__import__()</span></code></a> returns the toplevel module here because this is the object that is bound to a name by the <a class="reference internal" href="../reference/simple_stmts.html#import"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">import</span></code></a> statement.</p> <p>On the other hand, the statement <code class="docutils literal notranslate"><span class="pre">from</span> <span class="pre">spam.ham</span> <span class="pre">import</span> <span class="pre">eggs,</span> <span class="pre">sausage</span> <span class="pre">as</span> <span class="pre">saus</span></code> results in</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">_temp</span> <span class="o">=</span> <span class="nb">__import__</span><span class="p">(</span><span class="s1">'spam.ham'</span><span class="p">,</span> <span class="nb">globals</span><span class="p">(),</span> <span class="nb">locals</span><span class="p">(),</span> <span class="p">[</span><span class="s1">'eggs'</span><span class="p">,</span> <span class="s1">'sausage'</span><span class="p">],</span> <span class="mi">0</span><span class="p">)</span> <span class="n">eggs</span> <span class="o">=</span> <span class="n">_temp</span><span class="o">.</span><span class="n">eggs</span> <span class="n">saus</span> <span class="o">=</span> <span class="n">_temp</span><span class="o">.</span><span class="n">sausage</span> </pre></div> </div> <p>Here, the <code class="docutils literal notranslate"><span class="pre">spam.ham</span></code> module is returned from <a class="reference internal" href="#__import__" title="__import__"><code class="xref py py-func docutils literal notranslate"><span class="pre">__import__()</span></code></a>. From this object, the names to import are retrieved and assigned to their respective names.</p> <p>If you simply want to import a module (potentially within a package) by name, use <a class="reference internal" href="importlib.html#importlib.import_module" title="importlib.import_module"><code class="xref py py-func docutils literal notranslate"><span class="pre">importlib.import_module()</span></code></a>.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.3: </span>Negative values for <em>level</em> are no longer supported (which also changes the default value to 0).</p> </div> </dd></dl> <p class="rubric">Footnotes</p> <dl class="footnote brackets"> <dt class="label" id="id2"><span class="brackets"><a class="fn-backref" href="#id1">1</a></span></dt> <dd><p>Note that the parser only accepts the Unix-style end of line convention. If you are reading the code from a file, make sure to use newline conversion mode to convert Windows or Mac-style newlines.</p> </dd> </dl> </div> </div> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h4>Previous topic</h4> <p class="topless"><a href="intro.html" title="previous chapter">Introduction</a></p> <h4>Next topic</h4> <p class="topless"><a href="constants.html" title="next chapter">Built-in Constants</a></p> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li> <a href="https://github.com/python/cpython/blob/3.7/Doc/library/functions.rst" rel="nofollow">Show Source </a> </li> </ul> </div> </div> </div> <div class="clearer"></div> </div> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="constants.html" title="Built-in Constants" >next</a> |</li> <li class="right" > <a href="intro.html" title="Introduction" >previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <span class="language_switcher_placeholder">en</span> <span class="version_switcher_placeholder">3.7.4</span> <a href="../index.html">Documentation </a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="footer"> © <a href="../copyright.html">Copyright</a> 2001-2019, Python Software Foundation. <br /> The Python Software Foundation is a non-profit corporation. <a href="https://www.python.org/psf/donations/">Please donate.</a> <br /> Last updated on Jul 13, 2019. <a href="../bugs.html">Found a bug</a>? <br /> Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 2.0.1. </div> </body> </html>