Python对列表进行排序/先升后降 [英] Python sort list of lists / ascending and then decending

问题描述

如果我的列表包含一个看起来像这样的列表...

if i have a list that contains a list that looks like this ...

['a',1] ['a',2] ['a',3] ['b',1] ['b',2] ['b',3]

我该如何对它们进行排序，以便元素0降序排序，元素1升序排序，以便结果看起来像...

how can i sort them so that element 0 is sorted descending and element 1 sorted ascending so the result would look like...

['b',1] ['b',2] ['b',3] ['a',1] ['a',2] ['a',3]

使用itemgetter我可以反向传递元素0，但是我随后求助于element当然会破坏先前的排序.我无法执行组合键，因为它需要先降序然后升序.

Using itemgetter I can pass in reverse on element 0 but i I then resort against element to of course it ruins the previous sort. I can't do a combined key since it needs to first sort descending and then ascending.

TIA， PK

推荐答案

L = [['a',1], ['a',2], ['a',3], ['b',1], ['b',2], ['b',3]]
L.sort(key=lambda k: (k[0], -k[1]), reverse=True)

L现在包含:

[['b', 1], ['b', 2], ['b', 3], ['a', 1], ['a', 2], ['a', 3]]

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