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pythonregexcsvmerge

Merge two CSV files based on a data from the first column


I have two csv files like below that I'd like to merge - more or less using the first column ID_ as the unique identifier, and append the AMT column to a new column in the final file.

CSV1

ID_ CUSTOMER_ID_    EMAIL_ADDRESS_
1090    1   example1@example.com
1106    2   example2@example.com
1145    3   example3@example.com
1206    4   example4@example.com
1247    5   example5@example.com
1254    6   example6@example.com
1260    7   example7@example.com
1361    8   example8@example.com
1376    9   example9@example.com

CSV2


ID_ AMT
1090    5
1106    5
1145    5
1206    5
1247    5
1254    65
1260    5
1361    10
1376    5

Here's what I'm looking for in a final file:

ID_ CUSTOMER_ID_    EMAIL_ADDRESS_  AMT
1090    1   example1@example.com    5
1106    2   example2@example.com    5
1145    3   example3@example.com    5
1206    4   example4@example.com    5
1247    5   example5@example.com    5
1254    6   example6@example.com    65
1260    7   example7@example.com    5
1361    8   example8@example.com    10
1376    9   example9@example.com    5

I've tried modifying a this below as much as possible, but not able to get what I'm looking for. Really stuck on this - not sure what else I can do. Really appreciate any and all help!

join -t, File1.csv File2.csv

Data shows in this example contains tabs, but my actual files are CSVs as mentioned and will contain commas as a separator.


Solution

  • This can be easily done using Pandas library. Here is my code to do this:

    '''
    This program reads two csv files and merges them based on a common key column.
    '''
    # import the pandas library
    # you can install using the following command: pip install pandas
    
    import pandas as pd
    
    # Read the files into two dataframes.
    df1 = pd.read_csv('CSV1.csv')
    df2 = pd.read_csv('CSV2.csv')
    
    # Merge the two dataframes, using _ID column as key
    df3 = pd.merge(df1, df2, on = 'ID_')
    df3.set_index('ID_', inplace = True)
    
    # Write it to a new CSV file
    df3.to_csv('CSV3.csv')
    

    You can find a short tutorial on pandas here: https://pandas.pydata.org/pandas-docs/stable/getting_started/10min.html