pandas：统计一列列表中列表的每个元素的唯一出现次数

Question

我有一个包含一列列表的数据框，如下所示：

df

     pos_tag

0    ['Noun','verb','adjective']

1    ['Noun','verb']

2    ['verb','adjective']

3    ['Noun','adverb']

...

我想得到的是每个唯一元素作为字典出现在整个列中的次数：

desired output:

my_dict = {'Noun':3, 'verb':3, 'adjective':2, 'adverb':1}

Answer 1

与和Series.explode一起使用：Series.value_countsSeries.to_dictfreq = df['pos_tag'].explode().value_counts().to_dict()结果：# print(freq) {'Noun':3, 'verb':3, 'adjective':2, 'adverb':1}

Answer 2

为了提高性能，请使用Counter嵌套列表的展平值：from collections import Countermy_dict = dict(Counter([y for x in df['pos_tag'] for y in x]))print (my_dict){'Noun': 3, 'verb': 3, 'adjective': 2, 'adverb': 1}