Given two CSV files, each with a column containing the same kind of data:

• This script outputs a third CSV file that includes only the data from the second CSV that isn't in the first
• It the user wants, the script outputs a fourth CSV file that includes only the data from the first CSV that isn't in the second.

For example, if:

• foo.csv has a column tel_nos with phone numbers of contacts
• bar.csv has a column telephone with phone numbers of contacts

The script will compare the two columns and:

• write out a file of all the telephone numbers in bar.csv telephone that are not in foo.csv tel_nos
• optionally, write out a file of all the telephone numbers in foo.csv tel_nos that are not in bar.csv telephone.

• This script is part of the Name Filtering Tools project of They See Blue
• Copyright Surajit A. Bose © 2023.