How to generate categories by category

[Tiago Pereira]

Dear Statalist,

Not sure if I am missing something obvious in -egen-, but I couldn't figure out an easy way to do the following task:

clear
input str20 cat_A str20 cat_B
S1 C1
S1 C2
S2 C6
S2 C8
S3 C10
S3 C22
S3 C93
end

I would like to have as a result this:


cat_A cat_B cat_C
S1 C1 1
S1 C2 2
S2 C6 1
S2 C8 2
S3 C10 1
S3 C22 2
S3 C93 3


Thank you in advance for any tips.

All the best,

Tiago

[Friedrich Huebler]

sort cat_A cat_B
by cat_A: gen cat_C = _n

[Tiago Pereira]

Thank you so much, Friedrich. It worked like a charm.

All the best,

Tiago