all combinations of k numbers between 0 and n whose sum equals n, speed optimization

Question

I have this R function to generate a matrix of all combinations of k numbers between 0 and n whose sum equals n. This is one of the bottlenecks of my program as it becomes extre

Answer 1

The following can be done with lapply.

ls1 <- list()
for(i in 1:k) {
  ls1[[i]] <- 0:n
}

Try substituting this is and see if you get any speed up.

ls1 = lapply(1:k,function(x) 0:n)

I changed 'ls' to 'ls1' because ls() is an R function.