字典值总和列表 [英] sum list of dictionary values

问题描述

我有一个这样的字典列表:

I have a list of dictionary in this form :

[
{'signal_8': 1, 'signal_1': 7, 'signal_10': 5, 'signal_5': 2, 'signal_2': 5, 'signal_6': 3, 'signal_4': 9, 'signal_3': 6, 'signal_9': 4, 'signal_7': 8}, 

{'signal_8': 1, 'signal_1': 7, 'signal_10': 5, 'signal_5': 2, 'signal_2': 5, 'signal_6': 3, 'signal_4': 9, 'signal_3': 6, 'signal_9': 4, 'signal_7': 8},

{'signal_8': 1, 'signal_1': 7, 'signal_10': 5, 'signal_5': 2, 'signal_2': 5, 'signal_6': 3, 'signal_4': 9, 'signal_3': 6, 'signal_9': 4, 'signal_7': 8},
]

并且我想像这样对列表中的每个元素按键求和:

and I want to sum the values in this by key for each element in the list like that :

    {
     'signal_8': 3,
     'signal_1': 21,
     'signal_10': 15,
     'signal_5': 6,
     'signal_2': 15,
     'signal_6': 9,
     'signal_4': 27,
     'signal_3': 18,
     'signal_9': 12,
     'signal_7': 24
    }

我尝试过的是:

    result = {}
    sm = 0
    for elm in original_list:
        for k,v in elm.items():
            sm += v
            result[k] = sm
    print(result)

但是它仍然不起作用.

推荐答案

您想要的是Counter集合类型. 收藏上的Python文档对其进行了最好的描述，但实际上Counter是一种特殊的字典，其中所有值都是整数.您可以传递任何密钥(包括不存在的密钥)并将其添加.例如:

What you want is the Counter collection type. The Python docs on collections describe it best, but essentially a Counter is a special kind of dictionary where all the values are integers. You can pass any key, including nonexistent ones, and add to them. For example:

from collections import Counter

original_list = [
    {'signal_8': 1, 'signal_1': 7, 'signal_10': 5, 'signal_5': 2, 'signal_2': 5, 'signal_6': 3, 'signal_4': 9, 'signal_3': 6, 'signal_9': 4, 'signal_7': 8}, 
    {'signal_8': 1, 'signal_1': 7, 'signal_10': 5, 'signal_5': 2, 'signal_2': 5, 'signal_6': 3, 'signal_4': 9, 'signal_3': 6, 'signal_9': 4, 'signal_7': 8},
    {'signal_8': 1, 'signal_1': 7, 'signal_10': 5, 'signal_5': 2, 'signal_2': 5, 'signal_6': 3, 'signal_4': 9, 'signal_3': 6, 'signal_9': 4, 'signal_7': 8},
]

result = Counter()

for elem in original_list:
    for key, value in elem.items():
        result[key] += value

print(result)

@timgeb提供了此答案的一种变体，该变体在Counter对象上本地使用了update()方法.我建议将其作为此处的最佳答案

@timgeb provides a variation on this answer which makes native use of the update() method on Counter objects. I would recommend that as the best answer here

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