在Python中的列表中按字典排序键 [英] Sort keys in dictionary by value in a list in Python

问题描述

我已经看到这篇文章和这篇文章以及许多其他人，但还没有找到我的问题的答案，也不能弄清楚。

I have seen this post and this post as well as many others, but haven't quite found the answer to my question nor can I figure it out.

我有一个列表的字典。例如，它看起来像：

I have a dictionary of lists. For example it looks like:

Dict = {'a':[1,2,3,4], 'b':[9,8,7,6], 'c':[8,5,3,2]}

我想根据列表中的特定项目返回排序（降序/反向）的键列表。例如，我想根据每个列表中的第四个项目对a，b，c进行排序。

I want to return a list of the keys sorted (descending/reverse) based on a specific item in the lists. For example, I want to sort a,b,c based on the 4th item in each list.

这应该返回列表 sorted_keys = [按照值 [6,4,2] 排序的'b'，'a'，'c']

This should return the list sorted_keys = ['b','a','c'] which were sorted by values [6,4,2].

有意义吗？请帮助...谢谢！

Make sense? Please help...thanks!

推荐答案

提供键 lambda 是最简单的，排序方式：

Supply a key function, a lambda is easiest, and sort reversed:

sorted(Dict.keys(), key=lambda k: Dict[k][3], reverse=True)

关键功能告诉排序 要排序什么>

The key function tells sorted what to sort by; the 4th item in the value for the given key.

演示：

>>> sorted(Dict.keys(), key=lambda k: Dict[k][3], reverse=True)
['b', 'a', 'c']

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