动态大小的Python列表理解

Question

假设我有一个列表理解

[x,y,z] for x in a for y in a for z in a

假设这是我对尺寸 3 的理解我希望能够相应地修改它，所以对于 2，我将只有 x，y，对于 4，我将拥有 a、b、c、d 等...

有办法吗？

Answer 1

是的，您可以使用 product功能:

from itertools import product
a = [1,2,3]
print list(product(a))
# gives: [(1,), (2,), (3,)]
print list(product(a, a))
# gives: [(1, 1), (1, 2), (1, 3), (2, 1), (2, 2), (2, 3), (3, 1), (3, 2), (3, 3)]
print list(product(a, a, a))
# gives: [(1, 1, 1), (1, 1, 2), (1, 1, 3), (1, 2, 1), (1, 2, 2), (1, 2, 3), (1, 3, 1), (1, 3, 2), (1, 3, 3), (2, 1, 1), (2, 1, 2), (2, 1, 3), (2, 2, 1), (2, 2, 2), (2, 2, 3), (2, 3, 1), (2, 3, 2), (2, 3, 3), (3, 1, 1), (3, 1, 2), (3, 1, 3), (3, 2, 1), (3, 2, 2), (3, 2, 3), (3, 3, 1), (3, 3, 2), (3, 3, 3)]

或者使用 repeat 关键字更方便:

product(a, repeat=3)