Using "for" loop in r with a table

Question

I have the following database

library(data.table)
dt <- data.table(prod= c("AAAA","BBBB","CCCC"),
                 version= c(4,3,5))

And I want to obtain this

AAAA1
AAAA2
AAAA3
AAAA4
BBBB1
BBBB2
BBBB3
CCCC1
CCCC2
CCCC3
CCCC4
CCCC5

Now I have the following code, but it only works for the AAAA but not for the rest

list <- c()

for(i in 1:dt$version){
  
  list[[i]] <- paste0(dt$prod,i)
  
}

Answer 1

A base R option using rep + sequence + paste0

> with(dt,paste0(rep(prod,version),sequence(version)))
 [1] "AAAA1" "AAAA2" "AAAA3" "AAAA4" "BBBB1" "BBBB2" "BBBB3" "CCCC1" "CCCC2"
[10] "CCCC3" "CCCC4" "CCCC5"

or mapply + paste0 + seq

> with(dt, unlist(mapply(function(x,y) paste0(x,seq(y)), prod,version)))
  AAAA1   AAAA2   AAAA3   AAAA4   BBBB1   BBBB2   BBBB3   CCCC1   CCCC2   CCCC3
"AAAA1" "AAAA2" "AAAA3" "AAAA4" "BBBB1" "BBBB2" "BBBB3" "CCCC1" "CCCC2" "CCCC3"
  CCCC4   CCCC5
"CCCC4" "CCCC5"