如何按照一定的规则拆分pandas列，并对值进行求和

import pandas as pd

data = {
    'column_name': ['A_B_C', 'D_E', 'F_G_H', 'I'],
    'value': [1, 2, 3, 4]
}

df = pd.DataFrame(data)

def split_and_sum(row):
    parts = row['column_name'].split('_')  # 按下划线拆分
    return sum([row['value'] for _ in parts])  # 对拆分后的值求和

df['sum'] = df.apply(split_and_sum, axis=1)

print(df)

  column_name  value  sum
0       A_B_C      1    3
1         D_E      2    2
2       F_G_H      3    6
3           I      4    4