Pandas merge two dataframes with one to many relationship

Question

I am trying to merge two pandas DataFrames with one of many relationship.

import pandas as pd

df1 = pd.DataFrame({'name': ['AA', 'BB', 'CC'],
                    'col1': [1, 2, 3],
                    'col2': [1, 2, 3] })

df2 = pd.DataFrame({'name': ['AA', 'AA', 'BB'],
                    'col1': [1, 2, 3],
                    'col2': [1, 2, 3] })

df_merged = pd.merge(
                     df1, 
                     df2, 
                     left_on = 'name',
                     right_on = 'name',
                     how = "inner"
                    )

Answer 1

使用左连接并删除重复项

df1.merge(df2, how='left', on='name').drop_duplicates(subset='name',keep='first')