用groupby的结果填充panda dataframe中的列

import pandas as pd

# 创建示例DataFrame
data = {'A': ['foo', 'bar', 'foo', 'bar', 'foo', 'bar', 'foo', 'foo'],
        'B': ['one', 'one', 'two', 'two', 'two', 'one', 'two', 'one'],
        'C': [1, 2, 3, 4, 5, 6, 7, 8]}
df = pd.DataFrame(data)

# 使用groupby和transform填充列C
df['C_filled'] = df.groupby(['A', 'B'])['C'].transform('sum')

print(df)

     A    B  C  C_filled
0  foo  one  1         9
1  bar  one  2         2
2  foo  two  3         8
3  bar  two  4         4
4  foo  two  5         8
5  bar  one  6         2
6  foo  two  7         8
7  foo  one  8         9