Let's be the following two DataFrames in python:

df:

df_1:

I want to merge df with df_1:

    df_merge = pd.merge(df, df_1, how="left", on=['code_1'])

df_merge:

I want the merge to remove duplicates in the case of code_1 and only do the merge for the first row. I could do a drop_duplicates for [other, code_1], but I would like to know if it is possible to include some parameter in the merge function to do it directly.

Expected result:

CodePudding user response：

In my opinion there is no specifc parameter for pandas.merge() that fit your needs, but you could reduce the result by dropping duplicates before merging, assumed there are only duplicates in df_1:

df_merge = df.merge(df_1.drop_duplicates('code_1'), how="left", on=['code_1'])