itertools.prodcut

product(A, B)和((x,y) for x in A for y in B)的效果是一样的。

>>> from itertools import product as product
>>> A = [1, 2, 3]
>>> B = [100, 200, 300]
>>> for item in product(A, B):
...     print(item)
... 
(1, 100)
(1, 200)
(1, 300)
(2, 100)
(2, 200)
(2, 300)
(3, 100)
(3, 200)
(3, 300)

>>> for item in product(A, repeat=3):
...     print(item)
... 
(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)