python 排列组合

1. 调用 scipy 计算排列组合的具体数值

A23=6,(32)=3

>> from scipy.special import comb, perm
>> perm(3, 2)
6.0
>> comb(3, 2)
3.0

2. 调用 itertools 获取排列组合的全部情况数

>> from itertools import combinations, permutations
>> permutations([1, 2, 3], 2)
<itertools.permutations at 0x7febfd880fc0>
                # 可迭代对象
>> list(permutations([1, 2, 3], 2))
[(1, 2), (1, 3), (2, 1), (2, 3), (3, 1), (3, 2)]

>> list(combinations([1, 2, 3], 2))
[(1, 2), (1, 3), (2, 3)]