python: create iterator through subsets of a set for a loop

Question

I have a sequence of consecutive integers, for example [1, 2, 3]. I'd like to create an iterator that goes through all the subsets of the set. In this case [], [1],...,[1,2,3]. How could I do this?

Answer 1

The itertools documentation contains a recipe for this construction under the name powerset, if that's what you need.

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))