Powersets in Python using itertools

itertools functions return iterators, objects that produce results lazily, on demand.

You could either loop over the object with a for loop, or turn the result into a list by calling list() on it:

from itertools import chain, combinations

def powerset(iterable):
    "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
    s = list(iterable)
    return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))

for result in powerset([1, 2, 3]):

results = list(powerset([1, 2, 3]))

You can also store the object in a variable and use the next() function to get results from the iterator one by one.

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