Grouping unique values of one variable by a second variable

[Jared Thorpe]

Hello, Stata Community,

I am having trouble getting Stata to do what I need it to. I have a dataset with a long list of company names and a variable that identifies unique compounds. The issue I have is that the unique compound identifier is market level, so the same value may appear several times for the same company and again for separate companies. What I am trying to do is generate a new variable which assigns company level unique compound identifiers based on grouping the market level unique identifiers by company.

For example:
My data looks like this:

input byte unique str20 company
37 "Aurobindo Pharma"
42 "Aurobindo Pharma"
42 "Aurobindo Pharma"
20 "Avanthi Inc"     
20 "Avema Pharma"    
 4 "Barr"            
 4 "Barr"            
 4 "Barr"            
 4 "Barr"            
 4 "Barr"            
35 "Barr"            
end

And what I need is:

input byte unique str20 company byte cunique
37 "Aurobindo Pharma" 1
42 "Aurobindo Pharma" 2
42 "Aurobindo Pharma" 2
20 "Avanthi Inc" 1    
20 "Avema Pharma" 1   
 4 "Barr" 1           
 4 "Barr" 1           
 4 "Barr" 1           
 4 "Barr" 1           
 4 "Barr" 1           
35 "Barr" 2           
end

If I could use the by command with the egen, group() command it would be exactly what I need. Anyone know a way around this?

Thanks!

[Clyde Schechter]

by company (unique), sort: gen cunique = sum(unique != unique[_n-1])

[Jared Thorpe]

Thank you!!!