从列表中获取所有成对组合 [英] Get all pairwise combinations from a list

问题描述

例如，如果输入列表为

[1, 2, 3, 4]

我希望输出为

[[1,2], [1,3], [1,4], [2,3], [2,4], [3,4]]

如果可能的话，我想要一个比使用两个for循环的强力方法更好的解决方案.我该如何实现?

If possible, I would like a solution which is better than the brute force method of using two for loops. How do I implement this?

推荐答案

尽管先前的答案将为您提供所有成对的排序，但是示例预期结果似乎暗示您希望所有无序对.

Though the previous answer will give you all pairwise orderings, the example expected result seems to imply that you want all unordered pairs.

这可以通过 itertools.combinations 完成:

>>> import itertools
>>> x = [1,2,3,4]
>>> list(itertools.combinations(x, 2))
[(1, 2), (1, 3), (1, 4), (2, 3), (2, 4), (3, 4)]

与其他结果比较:

>>> list(itertools.permutations(x, 2))
[(1, 2), (1, 3), (1, 4), (2, 1), (2, 3), (2, 4), (3, 1), (3, 2), (3, 4), (4, 1), (4, 2), (4, 3)]

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