计算python字典中每个键的出现次数

问题描述

我有一个看起来像这样的python字典对象:

I have a python dictionary object that looks somewhat like this:

[{"house": 4,  "sign": "Aquarius"},
 {"house": 2,  "sign": "Sagittarius"},
 {"house": 8,  "sign": "Gemini"},
 {"house": 3,  "sign": "Capricorn"},
 {"house": 2,  "sign": "Sagittarius"},
 {"house": 3,  "sign": "Capricorn"},
 {"house": 10, "sign": "Leo"},
 {"house": 4,  "sign": "Aquarius"},
 {"house": 10, "sign": "Leo"},
 {"house": 1,  "sign": "Scorpio"}]

现在，对于每个符号"键，我想计算每个值出现多少次.

Now for each 'sign' key, I'd like to count how many times each value occurs.

def predominant_sign(data):
    signs = [k['sign'] for k in data if k.get('sign')]
    print len(signs)

但是，这会打印出"sign"出现在字典中的次数，而不是获取sign的值并计算出现特定值的次数.

This however, prints number of times 'sign' appears in the dictionary, instead of getting the value of the sign and counting the number of times a particular value appears.

例如，我想看到的输出是:

For example, the output I'd like to see is:

Aquarius: 2
Sagittarius: 2
Gemini: 1
...

以此类推.我应该改变什么以获得期望的输出?

And so on. What should I change to get the desired output?

推荐答案

使用 collections.Counter 及其 most_common方法:

from collections import Counter
def predominant_sign(data):
    signs = Counter(k['sign'] for k in data if k.get('sign'))
    for sign, count in signs.most_common():
        print(sign, count)

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