loop to append multiple files and add new variable

[Liza Sopina]

Hi there,

I have a number of files named filename1990.dta, filename1991.dta etc until 2018. I would like to write a loop doing two things:

1) append the files, and
2) create a variable 'year' corresponding to the file name (2004, 2005, 2006) to show me which year the data came from.

thanks in advance for your help!

Liza

[Andrew Musau]

forval i= 1990/2018{
   use filename`i'.dta, clear
   gen year=`i'
   save filename`i'.dta, replace
}
use filename1990.dta, clear
forval i=1991/2018{
   append using filename`i'.dta
}
save all.dta

It may be possible to do all in one loop:

use filename1990.dta, clear
gen year=1990
forval i=1991/2018{
   append using filename`i'.dta
   replace year= `i' if missing(year)
}
save all.dta

[Liza Sopina]

Brilliant, thanks