Python Dict 理解创建和更新字典

2022-01-22 00:00:00 python dictionary append dictionary-comprehension defaultdict

问题描述

我有一个字典(数据)列表，并希望将其转换为字典 (x)，如下所示.我正在使用以下'for循环'来实现.

I have a list of dictionaries (data) and want to convert it into dictionary (x) as below. I am using following ‘for loop’ to achieve.

data = [{'Dept': '0123', 'Name': 'Tom'},
        {'Dept': '0123', 'Name': 'Cheryl'},
        {'Dept': '0123', 'Name': 'Raj'},
        {'Dept': '0999', 'Name': 'Tina'}]
x = {}

for i in data:
    if i['Dept'] in x:
        x[i['Dept']].append(i['Name'])
    else:
        x[i['Dept']] = [i['Name']]

Output:
x -> {'0999': ['Tina'], '0123': ['Tom', 'Cheryl', 'Raj']}

是否可以在字典理解或任何其他更pythonic的方式中实现上述逻辑?

Is it possible to implement the above logic in dict comprehension or any other more pythonic way?

解决方案

dict 理解，即使不是不可能，也可能不是最好的选择.我可以建议使用 defaultdict (https://docs.python.org/2/library/collections.html#collections.defaultdict):

The dict comprehension, even though not impossible, might not be the best choice. May I suggest using defaultdict (https://docs.python.org/2/library/collections.html#collections.defaultdict):

from collections import defaultdict
dic = defaultdict(list)
for i in data:
    dic[i['Dept']].append(i['Name'])

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