itertools 中的排列无法打印所有排列

Question

我的问题很简单：-

在 python itertools 中，为什么我可以打印出说 [,r =3] 的所有排列：

>>>import itertools
>>>print list(itertools.permutations([1,2,3], 3))
[(1, 2, 3), (1, 3, 2), (2, 1, 3), (2, 3, 1), (3, 1, 2), (3, 2, 1)]

但是 [,r >3 例如 10] 只有一个空列表：

>>>print list(itertools.permutations([1,2,3], 10))
[] 

有办法绕过这个吗？？

Answer 1

如itertools docs 中所述，permutations() 不重复元素。

我想你想要combinations_with_replacement()

>>> from itertools import combinations_with_replacement

>>> print list(combinations_with_replacement([1, 2, 3], 10))

[(1, 1, 1, 1, 1, 1, 1, 1, 1, 1), (1, 1, 1, 1, 1, 1, 1, 1, 1, 2), (1, 1, 1, 1, 1, 1, 1, 1, 1, 3), (1, 1, 1, 1, 1, 1, 1, 1, 2, 2), (1, 1, 1, 1, 1, 1, 1, 1, 2, 3), (1, 1, 1, 1, 1, 1, 1, 1, 3, 3), (1, 1, 1, 1, 1, 1, 1, 2, 2, 2), (1, 1, 1, 1, 1, 1, 1, 2, 2, 3), (1, 1, 1, 1, 1, 1, 1, 2, 3, 3), (1, 1, 1, 1, 1, 1, 1, 3, 3, 3), (1, 1, 1, 1, 1, 1, 2, 2, 2, 2), (1, 1, 1, 1, 1, 1, 2, 2, 2, 3), (1, 1, 1, 1, 1, 1, 2, 2, 3, 3), (1, 1, 1, 1, 1, 1, 2, 3, 3, 3), (1, 1, 1, 1, 1, 1, 3, 3, 3, 3), (1, 1, 1, 1, 1, 2, 2, 2, 2, 2), (1, 1, 1, 1, 1, 2, 2, 2, 2, 3), (1, 1, 1, 1, 1, 2, 2, 2, 3, 3), (1, 1, 1, 1, 1, 2, 2, 3, 3, 3), (1, 1, 1, 1, 1, 2, 3, 3, 3, 3), (1, 1, 1, 1, 1, 3, 3, 3, 3, 3), (1, 1, 1, 1, 2, 2, 2, 2, 2, 2), (1, 1, 1, 1, 2, 2, 2, 2, 2, 3), (1, 1, 1, 1, 2, 2, 2, 2, 3, 3), (1, 1, 1, 1, 2, 2, 2, 3, 3, 3), (1, 1, 1, 1, 2, 2, 3, 3, 3, 3), (1, 1, 1, 1, 2, 3, 3, 3, 3, 3), (1, 1, 1, 1, 3, 3, 3, 3, 3, 3), (1, 1, 1, 2, 2, 2, 2, 2, 2, 2), (1, 1, 1, 2, 2, 2, 2, 2, 2, 3), (1, 1, 1, 2, 2, 2, 2, 2, 3, 3), (1, 1, 1, 2, 2, 2, 2, 3, 3, 3), (1, 1, 1, 2, 2, 2, 3, 3, 3, 3), (1, 1, 1, 2, 2, 3, 3, 3, 3, 3), (1, 1, 1, 2, 3, 3, 3, 3, 3, 3), (1, 1, 1, 3, 3, 3, 3, 3, 3, 3), (1, 1, 2, 2, 2, 2, 2, 2, 2, 2), (1, 1, 2, 2, 2, 2, 2, 2, 2, 3), (1, 1, 2, 2, 2, 2, 2, 2, 3, 3), (1, 1, 2, 2, 2, 2, 2, 3, 3, 3), (1, 1, 2, 2, 2, 2, 3, 3, 3, 3), (1, 1, 2, 2, 2, 3, 3, 3, 3, 3), (1, 1, 2, 2, 3, 3, 3, 3, 3, 3), (1, 1, 2, 3, 3, 3, 3, 3, 3, 3), (1, 1, 3, 3, 3, 3, 3, 3, 3, 3), (1, 2, 2, 2, 2, 2, 2, 2, 2, 2), (1, 2, 2, 2, 2, 2, 2, 2, 2, 3), (1, 2, 2, 2, 2, 2, 2, 2, 3, 3), (1, 2, 2, 2, 2, 2, 2, 3, 3, 3), (1, 2, 2, 2, 2, 2, 3, 3, 3, 3), (1, 2, 2, 2, 2, 3, 3, 3, 3, 3), (1, 2, 2, 2, 3, 3, 3, 3, 3, 3), (1, 2, 2, 3, 3, 3, 3, 3, 3, 3), (1, 2, 3, 3, 3, 3, 3, 3, 3, 3), (1, 3, 3, 3, 3, 3, 3, 3, 3, 3), (2, 2, 2, 2, 2, 2, 2, 2, 2, 2), (2, 2, 2, 2, 2, 2, 2, 2, 2, 3), (2, 2, 2, 2, 2, 2, 2, 2, 3, 3), (2, 2, 2, 2, 2, 2, 2, 3, 3, 3), (2, 2, 2, 2, 2, 2, 3, 3, 3, 3), (2, 2, 2, 2, 2, 3, 3, 3, 3, 3), (2, 2, 2, 2, 3, 3, 3, 3, 3, 3), (2, 2, 2, 3, 3, 3, 3, 3, 3, 3), (2, 2, 3, 3, 3, 3, 3, 3, 3, 3), (2, 3, 3, 3, 3, 3, 3, 3, 3, 3), (3, 3, 3, 3, 3, 3, 3, 3, 3, 3)]