使用循环将dataframe中列中的每一行替换为它出现的实例

import pandas as pd

data = {'col1': ['A', 'B', 'C', 'A', 'B'],
        'col2': ['X', 'Y', 'Z', 'X', 'Y']}
df = pd.DataFrame(data)

for index, row in df.iterrows():
    df.at[index, 'col1'] = df[df['col1'] == row['col1']]['col2'].values[0]

print(df)

import pandas as pd

data = {'col1': ['A', 'B', 'C', 'A', 'B'],
        'col2': ['X', 'Y', 'Z', 'X', 'Y']}
df = pd.DataFrame(data)

for index, row in df.iterrows():
    df.at[index, 'col1'] = df[df['col1'] == row['col1']]['col2'].values[0]

print(df)