Expanding the list of observations

[Marco Tacchi]

Hello,

I've been wrapping my head around the following problem but could not come up to a feasible and simple solution.

Essentially, I need to go from this structure

Firm1    Firm2    StartYear    EndYear
1    2    2010    2012
1    3    2010    2013
4    5    2008    2009
5    6    2007    2007

to this one

Firm1    Firm2    Year
1    2    2010
1    2    2011
1    2    2012
1    3    2010
1    3    2011
1    3    2012
1    3    2013
4    5    2008
4    5    2009
5    6    2007

So essentially, I need to create data for each Firm1-Firm2 combination ranging from the start year to the end year.

Would be thankful for any help.

[Nick Cox]

clear 
input Firm1    Firm2    StartYear    EndYear
1    2    2010    2012
1    3    2010    2013
4    5    2008    2009
5    6    2007    2007
end 

gen toexpand = End - Start + 1 
expand toexpand 
bysort Firm1 Firm2 : gen Year = StartYear[1] + _n - 1 
list, sepby(Firm1 Firm2)

[Marco Tacchi]

clear
input Firm1 Firm2 StartYear EndYear
1 2 2010 2012
1 3 2010 2013
4 5 2008 2009
5 6 2007 2007
end

gen toexpand = End - Start + 1
expand toexpand
bysort Firm1 Firm2 : gen Year = StartYear[1] + _n - 1
list, sepby(Firm1 Firm2)

Thank you very much, Nick!