I have two variables, Names1 and Names2, both consisting of certain names. A simplified e.g. is pasted below:
Names1 Names2
AA CC
BB AA
CC HH
DD FF
EE GG
FF
GG
HH

I would like to drop the names in Names1 which are not in Names2. So in this e.g. I want to drop BB, DD, EE. Would appreciate if you someone could provide guidance on doing so.