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function to load a relation from iterators

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Salvo 'LtWorf' Tomaselli 2020-08-15 20:54:58 +02:00
parent 94404f60f9
commit 1bbef1f1b8
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1 changed files with 21 additions and 3 deletions
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relational/relation.py
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@ -62,12 +62,30 @@ class Relation(NamedTuple):
@staticmethod
def load(filename: Union[str, Path]) -> 'Relation':
'''
Load a relation object from a csv file.
The 1st row is the header and the other rows are the content.
'''
with open(filename) as fp:
reader = csv.reader(fp) # Creating a csv reader
header = Header(next(reader)) # read 1st line
#FIXME load properly
content = frozenset((tuple(Rstring(s) for s in i) for i in reader))
return Relation(header, content)
return Relation.create_from(header, reader)
@staticmethod
def create_from(header: Iterable[str], content: Iterable[Iterable[str]]) -> 'Relation':
'''
Iterator for the header, and iterator for the content.
'''
header = Header(header)
r_content: List[Tuple[Rstring, ...]] = []
for row in content:
content_row: Tuple[Rstring, ...] = tuple(Rstring(i) for i in row)
if len(content_row) != len(header):
raise ValueError(f'Line {row} contains an incorrect amount of values')
r_content.append(content_row)
return Relation(header, frozenset(r_content))
def __iter__(self):
return iter(self.content)