将python中的字典反转为key:值列表? [英] Reverse a dictionary in python to key : list of values?

问题描述

如何将python字典d = {1:10, 2:20, 3:30, 4:30}转换为{10: [1], 20: [2], 30: [3, 4]}?

How to convert a python dictionary d = {1:10, 2:20, 3:30, 4:30} to {10: [1], 20: [2], 30: [3, 4]}?

我需要反转字典，其值应成为另一本字典的键，并且值应是列表中的键，即排序后的内容中的键.

I need to reverse a dictionary the values should become the keys of another dictionary and the values should be key in a list i.e. also in the sorted matter.

推荐答案

d = {1:10, 2:20, 3:30, 4:30}
inv = {}
for key, val in d.iteritems():
    inv[val] = inv.get(val, []) + [key]

尝试一下！

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