dict.fromkeys 都指向同一个列表 [英] dict.fromkeys all point to same list

问题描述

这让我有点难过...

我从列表中创建了一个字典

l = ['a','b','c']d = dict.fromkeys(l, [0,0]) # 用 [0,0] 作为值初始化字典d['a'] 是 d['b'] # 返回真

如何使字典的每个值成为一个单独的列表?如果不迭代所有键并将它们设置为等于列表，这可能吗?我想修改一个列表而不更改所有其他列表.

解决方案

你可以使用字典理解:

<预><代码>>>>键 = ['a','b','c']>>>值 = [0, 0]>>>{key: list(value) for key in keys}{'a': [0, 0], 'b': [0, 0], 'c': [0, 0]}

This was causing me a bit of grief...

I created a dictionary from a list

l = ['a','b','c']
d = dict.fromkeys(l, [0,0]) # initializing dictionary with [0,0] as values

d['a'] is d['b'] # returns True

How can I make each value of the dictionary a seperate list? Is this possible without iterating over all keys and setting them equal to a list? I'd like to modify one list without changing all the others.

解决方案

You could use a dict comprehension:

>>> keys = ['a','b','c']
>>> value = [0, 0]
>>> {key: list(value) for key in keys}
    {'a': [0, 0], 'b': [0, 0], 'c': [0, 0]}

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