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Replace intermediate lists with iterators

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Some more intermediate lists created during joins are now
not created in favour of iterators instead
This commit is contained in:
Salvo 'LtWorf' Tomaselli 2015-06-05 18:15:03 +02:00
parent f974fc316d
commit d05c2e2d3c
1 changed files with 8 additions and 13 deletions
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21
relational/relation.py
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@ -297,7 +297,7 @@ class relation (object):
newt.header = header(list(self.header.attributes))
# Adds all the attributes of the 2nd, when non shared
for i in other.header.attributes:
for i in other.header:
if i not in shared:
newt.header.attributes.append(i)
# Shared ids of self
@ -306,10 +306,7 @@ class relation (object):
oid = other.header.getAttributesId(shared)
# Non shared ids of the other relation
noid = []
for i in range(len(other.header.attributes)):
if i not in oid:
noid.append(i)
noid = [i for i in range(len(other.header)) if i not in oid]
for i in self.content:
# Tuple partecipated to the join?
@ -320,17 +317,13 @@ class relation (object):
match = match and (i[sid[k]] == j[oid[k]])
if match:
item = list(i)
for l in noid:
item.append(j[l])
item = chain(i,(j[l] for l in noid))
newt.content.add(tuple(item))
added = True
# If it didn't partecipate, adds it
if not added:
item = list(i)
for l in range(len(noid)):
item.append("---")
item = chain(i,repeat('---',len(noid)))
newt.content.add(tuple(item))
return newt
@ -340,8 +333,7 @@ class relation (object):
shared attributes, it will behave as cartesian product.'''
# List of attributes in common between the relations
shared = list(set(self.header.attributes)
.intersection(set(other.header.attributes)))
shared = set(self.header).intersection(set(other.header))
newt = relation() # Creates the new relation
@ -548,6 +540,9 @@ class header (object):
def __iter__(self):
return iter(self.attributes)
def __len__(self):
return len(self.attributes)
def getAttributesId(self, param):
'''Returns a list with numeric index corresponding to field's name'''
return [self.attributes.index(i) for i in param]