动态大小的Python列表理解

Question

我想有一个列表理解

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

假设这是理解我得到了规模3 我希望能够相应地修改它，2我只会有X ，y为4我会像a，b，c，d等...

有没有办法做到这一点？

Answer 1

是的，你可以使用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)] 

，或者更方便与repeat关键字：

product(a, repeat=3)