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 popA1989, popB1989, popC1989, popD1989 already exist in your global environment, the code below should work. There are certainly more "R-like" ways to do this, but I wanted to give you something similar to your Stata code.

for(L in LETTERS[1:4]) {
  for(i in 1990:2000) {
    new <- paste("pop",L,i,sep="")  # create name for new variable
    old <- get(paste("pop",L,i-1,sep=""))  # get old variable
    trend <- get(paste("trend",i,sep=""))  # get trend variable
    assign(new, old*(1+trend))
  }
}