Pandas DataFrame应用或映射字典值MultiIndex列到Pandas值的函数

import pandas as pd

# 创建一个包含MultiIndex列的DataFrame对象
data = {'A': [1, 2, 3, 4, 5],
        'B': [6, 7, 8, 9, 10]}
index = pd.MultiIndex.from_tuples([('x', 'a'), ('x', 'b'), ('y', 'a'), ('y', 'b'), ('z', 'a')], names=['index1', 'index2'])
df = pd.DataFrame(data, index=index)

# 定义一个字典，用于映射目标值
mapping = {('x', 'a'): 'apple', ('x', 'b'): 'banana', ('y', 'a'): 'cat', ('y', 'b'): 'dog', ('z', 'a'): 'elephant'}

# 使用apply函数映射字典值到MultiIndex列
df['C'] = df.apply(lambda row: mapping[(row.name[0], row.name[1])], axis=1)

print(df)

              A   B         C
index1 index2               
x      a      1   6     apple
       b      2   7    banana
y      a      3   8       cat
       b      4   9       dog
z      a      5  10  elephant