Python Merge Two DataFrames Only Retrieve Specific Columns in the Result

Question

Hi - I want to merge two python DataFrames, but don't want to bring over ALL of the columns from both dataframes to my new dataframe. In the picture below, if I join df1 and df2 on 'acct' and want to bring back all the columns from df1 and ONLY 'entity' from df2, how would I write that? I don't want to have to drop any columns so doing a normal merge isn't what I'm looking for. Can anyone help? Thanks!

A DUBEY · Accepted Answer · 2020-12-10 04:39:43Z

2

When you perform the merge operation, you can modify a dataframe object that is in your function, which will mean the underlying objects df1 and df2 remain unchanged. An example would look like this:

df_result = df1.merge(df2[ ['acct','entity'] ], on ='acct')

This will let you do your partial merge without modifying either original dataframe.

edited Dec 10, 2020 at 4:39

A DUBEY

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answered Dec 10, 2020 at 3:05

Anderson Monken

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2 Comments

Jim Over a year ago

Thank you for the response! One additional question, what if the joining columns are differently named in the above example. Say, if df1 had a column 'acct' and df2 had 'account', but I still only wanted to bring back certain columns like in my original post. Thanks again!

Mayank Porwal Over a year ago

If column names that you want to join on are different, you can do this: df_result = df1.merge(df2[['account','entity']], left_on ='acct', right_on='account').

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