最快的方法是使用itertools，尤其是链和组合：
>>> from itertools import chain, combinations
>>> i = set([1, 2, 3])
>>> for z in chain.from_iterable(combinations(i, r) for r in range(len(i)+1)):
print z
()
(1,)
(2,)
(3,)
(1, 2)
(1, 3)
(2, 3)
(1, 2, 3)
>>>
def powerset_generator(i):
for subset in chain.from_iterable(combinations(i, r) for r in range(len(i)+1)):
yield set(subset)
然后简单地：
>>> for i in powerset_generator(i):
print i
set([])
set([1])
set([2])
set([3])
set([1, 2])
set([1, 3])
set([2, 3])
set([1, 2, 3])
>>>
602392714
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