合并具有相同键的元组 [英] Merge tuples with the same key

问题描述

如何合并具有相同键的元组

How to merge a tuple with the same key

list_1 = [("AAA", [123]), ("AAA", [456]), ("AAW", [147]), ("AAW", [124])]

然后把它们变成

list_2 = [("AAA", [123, 456]), ("AAW", [147, 124])]

推荐答案

最高效的方法是使用 collections.defaultdict 字典将数据存储为扩展列表，然后在需要时转换回元组/列表:

The most performant approach is to use a collections.defaultdict dictionary to store data as an expanding list, then convert back to tuple/list if needed:

import collections

list_1 = [("AAA", [123]), ("AAA", [456]), ("AAW", [147]), ("AAW", [124])]

c = collections.defaultdict(list)
for a,b in list_1:
    c[a].extend(b)  # add to existing list or create a new one

list_2 = list(c.items())

结果:

[('AAW', [147, 124]), ('AAA', [123, 456])]

请注意，转换后的数据最好保留为字典.再次转换为list，失去了字典的key"特性.

note that the converted data is probably better left as dictionary. Converting to list again loses the "key" feature of the dictionary.

另一方面，如果您想保留原始元组列表的键"的顺序，除非您使用的是python 3.6/3.7，否则您必须使用原始键"创建一个列表"(有序，唯一)，然后从字典中重建列表.或者使用 OrderedDict 但你不能使用 defaultdict(或使用 食谱)

On the other hand, if you want to retain the order of the "keys" of the original list of tuples, unless you're using python 3.6/3.7, you'd have to create a list with the original "keys" (ordered, unique), then rebuild the list from the dictionary. Or use an OrderedDict but then you cannot use defaultdict (or use a recipe)

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