How to rewrite this Stata code in R?

Question

One of the things Stata does well is the way it constructs new variables (see example below). How to do this in R?

foreach i in A B C D {  
    forval n=1990         


        

Answer 1

Assuming you have population data in vector pop1989 and data for trend in trend.

require(stringr)# because str_c has better default for sep parameter
dta <- kronecker(pop1989,cumprod(1+trend))
names(dta) <- kronecker(str_c("pop",LETTERS[1:4]),1990:2000,str_c)