python - 将 Count 连接到 pandas 中的原始 DataFrame

Question

将数据框作为

import pandas as pd 
lst = ['Yes', 'No', 'Maybe', 'Yes', 'No', 'Maybe', 'Yes'] 
lst2 = [11, 22, 33, 44, 55, 66, 77] 
df = pd.DataFrame(list(zip(lst, lst2)), 
               columns =['Name', 'val'])

我曾经在下面获取 GroupBy Count

countData=df.groupby("Name")["Name"].count()
countData

Name

Maybe 2

No 2

Yes 3

如何将countData加入DF？

Answer 1

您可以使用转换:

df['countData'] = df.groupby("Name")["Name"].transform(lambda x: x.count())

df:

    Name    val countData
0   Yes     11  3
1   No      22  2
2   Maybe   33  2
3   Yes     44  3
4   No      55  2
5   Maybe   66  2
6   Yes     77  3