Hello,

I am relatively new to stata, but I have encountered a problem of not being able to find duplicates across variables. I have a table like this:

id Start Destination
1 China US
2 US Japan
3 US China
4 Italy Spain

and I would like to find a list of all the observations that have another's start as destination and destination as start. I would like a result like this:


1 China US
3 US China


Thanks a ton to anyone that would help! I'd really appreciate it : )