how to join elements (chars) from a list into a single element in R?

I'm trying to create a simple script in R to simulate environmental pressure on genes so I have this following random generator of ATCG:

list <- c("A","T","C","G")
samp <- sample(list, 1000, replace = T)
display <- function(a,b,c) {
    result <- sample(list, 1000, replace = T)
    return(result)
}

a <- display(a)

b <- display(b)

c <- display(c)

The code is working fine but is conceptually wrong because the codon need to be joined as a group of characters not by a single one. So my question is, how to join this elements (1:4,5:8,...107:110) ?

I know there's many packages about genetics in R but I'm trying to keep it very simple just to use as an exercise on my genetics study group.

Thanks in advance!

Solution

Maybe this is what you had in mind:

dat <- setNames( data.frame(
  replicate(3, replicate( 1000,
  paste0(sample(c("A","C","T","G"),4, replace=T),collapse="") ) ) ),
  c("a","b","c") )

Result

dat
      a    b    c
1  CATG CTAG CGAT
2  AGCT GACT TGAC
3  TCAG TAGC TCAG
4  CGAT GACT GTAC
5  TCGA TAGC CTGA
...etc

You should be able to do the comparisons with dat$a,dat$b and dat$c