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'''Algorithm functions.'''
from collections import OrderedDict
def flatten(iterable):
'''Flatten a list of iterables into a single list.'''
result = []
for item in iterable:
result.extend(item)
return result
def uniq(iterable):
'''Return list of unique items, preserving order.'''
result = []
seen = set()
for item in iterable:
if item not in seen:
seen.add(item)
result.append(item)
return result
def partition(iterable, predicate):
'''Split an iterable into two lists based on a predicate.
Args:
iterable:
The input iterable to split.
predicate (callable):
A function returning True or False for each element.
Returns:
tuple: (matched, unmatched) where
matched -- list of items for which predicate(item) is True
unmatched -- list of items for which predicate(item) is False
'''
a, b = [], []
for item in iterable:
if predicate(item):
a.append(item)
else:
b.append(item)
return (a, b)
def group_by(iterable, keyfunc):
'''Group items from an iterable by a key function.
Args:
iterable:
The input iterable of items to group.
keyfunc (callable):
Function applied to each item to determine its group key.
Returns:
OrderedDict:
A mapping of key -> list of items with that key, preserving
the order of first appearance of each key.
'''
result = OrderedDict()
for item in iterable:
val = keyfunc(item)
if val in result:
result[val].append(item)
else:
result[val] = [item]
return result
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