Powersets in Python using itertools

I'm trying to create a powerset in Python 3. I found a reference to the itertools module, and I've used the powerset code provided on that page. The problem: the code returns a reference to an itertools.chain object, whereas I want access to the elements in the powerset. My question: how to accomplish this?

Many thanks in advance for your insights.

Solution

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]):
    print(result)

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

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