使用多索引Dataframe更新二维Dataframe Python

import pandas as pd

# 创建一个多索引DataFrame
arrays = [
    ['A', 'A', 'B', 'B'],
    ['one', 'two', 'one', 'two']
]
index = pd.MultiIndex.from_arrays(arrays, names=('first', 'second'))
df_multi_index = pd.DataFrame({'value': [10, 20, 30, 40]}, index=index)

# 创建一个二维DataFrame
df_2d = pd.DataFrame({
    'first': ['A', 'A', 'B', 'B'],
    'second': ['one', 'two', 'one', 'two'],
    'value': [0, 0, 0, 0]
})

# 更新df_2d
for idx in df_multi_index.index:
    df_2d.loc[(idx[0], idx[1]), 'value'] = df_multi_index.loc[idx, 'value']

print(df_2d)

# 确保索引匹配
df_2d = df_2d.set_index(['first', 'second'])
df_2d.update(df_multi_index)
df_2d = df_2d.reset_index()

# 使用merge进行批量更新
df_2d = df_2d.merge(df_multi_index, left_on=['first', 'second'], right_index=True, how='left')