Generating IDs

[Vinh Ng]

Dear all,

Suppose I have the following dataset

clear
input var1 var2
1 1
1 2
1 3
1 4
2 1
2 2
2 3
2 4
3 1
3 2
3 3
3 4
4 1
4 2
4 3
4 4
end

I'd like to create a list of IDs based on var1 and var2. In particular, I'd like to get the same ID when the observations in var1 and var2 are swapped. For example, var1=3 and var2=4 should have the same ID as where var1=4 and var2=3.

I have tried

 egen id = group(var1 var2)

but it doesn't not give me exactly what I'm looking for.

Could anyone please help me with this?

Thank you very much for your help,

Vinh

[Clyde Schechter]

gen sorted_pair = string(min(var1, var2)) + ";" + string(max(var1,var2))
egen wanted = group(sorted_pair), label
drop sorted_pair

[Vinh Ng]

Many thanks for your help, Clyde. Your code works perfectly.

Cheers,

Vinh

[Nick Cox]

See also https://www.stata-journal.com/articl...article=dm0043 for a broader discussion.

[Vinh Ng]

Thank you for the link, Nick.

Cheers,

Vinh