解压缩Python中的字典列表 [英] Unpack list of dictionaries in Python

问题描述

根据此答案，在Python 3.5或更高版本中，可以合并两个词典x和y打开它们的包装:

According to this answer, in Python 3.5 or greater, it is possible to merge two dictionaries x and y by unpacking them:

z = {**x, **y}

是否可以解压缩各种字典?像

Is it possible to unpack a variadic list of dictionaries? Something like

def merge(*dicts):
    return {***dicts} # this fails, of course. What should I use here?

例如，我希望

list_of_dicts = [{'a': 1, 'b': 2}, {'c': 3}, {'d': 4}]
{***list_of_dicts} == {'a': 1, 'b': 2, 'c': 3, 'd': 4}

请注意，此问题与如何合并字典列表无关，因为上面的链接提供了对此的答案.这里的问题是:是否可以解压缩字典列表?如何解压缩字典列表?

Note that this question is not about how to merge lists of dictionaries since the link above provides an answer to this. The question here is: is it possible, and how, to unpack lists of dictionaries?

如评论中所述，此问题与

As stated in the comments, this question is very similar to this one. However, unpacking a list of dictionaries is different from simply merging them. Supposing that there was an operator *** designed to unpack lists of dictionaries, and given

def print_values(a, b, c, d):
    print('a =', a)
    print('b =', b)
    print('c =', c)
    print('d =', d)

list_of_dicts = [{'a': 1, 'b': 2}, {'c': 3}, {'d': 4}]

有可能写

print_values(***list_of_dicts)

代替

print_values(**merge(list_of_dicts))

推荐答案

另一个解决方案是使用collections.ChainMap

Another solution is using collections.ChainMap

from collections import ChainMap

dict(ChainMap(*list_of_dicts[::-1]))

Out[88]: {'a': 1, 'b': 2, 'c': 3, 'd': 4}

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