一组python的幂集和笛卡尔积

Question

I am trying to find the cartesian product of two different sets. I can not find anything on the web about cartesian products of sets it's either of list or dictionaries.

Also power set is very confusing.

Neither one of these are in my book I have been using.

Could one of yall point me to the right direction.

Answer 1

For the Cartesian product, check outitertools.product .

For the powerset, the itertools docs also give us a recipe:

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 example:

>>> test = {1, 2, 3}
>>> list(powerset(test))
[(), (1,), (2,), (3,), (1, 2), (1, 3), (2, 3), (1, 2, 3)]
>>> list(product(test, test))
[(1, 1), (1, 2), (1, 3), (2, 1), (2, 2), (2, 3), (3, 1), (3, 2), (3, 3)]