数学与python中的几个列表

Question

我试图在python中获得三个不同列表的所有可能组合

说我有三个名单

A = [2,3,4,7,9]
B = [2,3,5]
C = [1,2]

我想返回所有组合为真的A [i] + B [j] -C [k] == 3

D = [[i,j,k] for i in A for j in B for k in C]

以列表格式给出了所有组合，但是如何从这里继续？

Answer 1

您可以使用itertools.product的列表理解来检查每个组合，看它是否符合您的条件。

>>> from itertools import product
>>> [(a,b,c) for a,b,c in product(A,B,C) if a + b - c == 3]
[(2, 2, 1), (2, 3, 2), (3, 2, 2)]

Answer 2

只需添加if i+j-k == 3即可。您不希望A[i]等为每个list编制索引，而i，j和k已经是元素本身。< / p>

D = [[i,j,k] for i in A for j in B for k in C if i+j-k == 3]

您还应该查看itertools.product以避免这样嵌套：

import itertools
D = [[i,j,k] for i,j,k in itertools.product(A, B, C) if i+j-k == 3]

Answer 3

只需在最后添加条件：

>>> D = [[i,j,k] for i in A for j in B for k in C if i + j - k == 3]
>>> D
[[2, 2, 1], [2, 3, 2], [3, 2, 2]]