I have a data set where I need to group the duplicate records and then see if any of the group has been flagged; if so, I need to indicate that it has been flagged in a new column.

Sample input; the “Concat” column is where I’m looking for duplicates:

Customer_Reference  Auth_ID Concat  Flag
C001    A1234   AAA TRUE
C002    A758    AAA FALSE
C003    A6149   BBB FALSE
C004    A5271   CCC FALSE
C005    A0124   BBB FALSE

The behaviour I’m looking for is that “AAA” is a duplicate where at least one of them has the Flag of “TRUE”; therefore, it should be marked as “TRUE” in the (to be added) column.

I’ve been able to mark the duplicate records, and the groupby function seems to chunk it up correctly, but I can’t work out how to then apply an “If-Then” to each group to assign a value to the new column