如何从python的同一列表中获取不同长度的多个组合？

Question

Suppose I have the tuple (3, 2, 1, 4). I would like to find every possible combination that involves taking 3 elements from range(5), 2 elements from range(5), 1 elements from range(5), and then 4 elements from range(5). The order between each individual combination matters, so I cannot just take combinations of length 9 from range(5) or something like that.

In case what I wrote above wasn't clear, a sample combination might be

[0, 1, 4,   2, 3,   2,   0, 1, 2, 3].

I introduced the spacing in the list above just to make it clear that the ordering between them matters.

I imagine that this should be simple to implement with itertools, but I just don't know how.

Answer 1

Assuming you are looking for combinations rather than permutations , the following should do what you want.

from itertools import chain, combinations, product

lengths = (3, 2, 1, 4)
for L in product(*(combinations(range(5), length) for length in lengths)):
    print(list(chain.from_iterable(L)))

Answer 2

if the order is important for you this give you what you want :

>>> l1=list(combinations(range(5), 1))
>>> l2=list(combinations(range(5), 2))
>>> l3=list(combinations(range(5), 3))
>>> l4=list(combinations(range(5), 4))

>>> tl=[l3,l2,l1,l4]
>>> list(product(*tl))

[((0, 1, 2), (0, 1), (0,), (0, 1, 2, 3)), ((0, 1, 2), (0, 1), (0,), (0, 1, 2, 4)), ((0, 1, 2), (0, 1), (0,), (0, 1, 3, 4)), ((0, 1, 2), (0, 1), (0,), (0, 2, 3, 4)), ((0, 1, 2), (0, 1), (0,), (1, 2, 3, 4)), ((0, 1, 2), (0, 1), (1,), (0, 1, 2, 3)), ((0, 1, 2), (0, 1), (1,), (0, 1, 2, 4)), ((0, 1, 2), (0, 1), (1,), (0, 1, 3, 4)), ((0, 1, 2), (0, 1), (1,), (0, 2, 3, 4)), ((0, 1, 2), (0, 1), (1,), (1, 2, 3, 4)), ((0, 1, 2), (0, 1), (2,), (0, 1, 2, 3)), ((0, 1, 2), (0, 1), (2,), (0, 1, 2, 4)), ((0, 1, 2), (0, 1), (2,), (0, 1, 3, 4)), ((0, 1, 2), (0, 1), (2,), (0, 2, 3, 4)), ((0, 1, 2), (0, 1), (2,), (1, 2, 3, 4)), ((0, 1, 2), (0, 1), (3,), (0, 1, 2, 3)), ((0, 1, 2), (0, 1), (3,), (0, 1, 2, 4)), ((0, 1, 2), (0, 1), (3,), (0, 1, 3, 4)), ((0, 1, 2), (0, 1), (3,), (0, 2, 3, 4)), ((0, 1, 2), (0, 1), (3,), (1, 2, 3, 4)), ((0, 1, 2), (0, 1), (4,), (0, 1, 2, 3)), ((0, 1, 2), (0, 1), (4,), (0, 1, 2, 4)), ((0, 1, 2), (0, 1), (4,), (0, 1, 3, 4)), ((0, 1, 2), (0, 1), (4,), (0, 2, 3, 4)), ((0, 1, 2), (0, 1), (4,), (1, 2, 3, 4)), ((0, 1, 2)