repeating vector of letters

Question

Is there a function to create a repeating list of letters in R?

something like

letters[1:30]
[1] \"a\" \"b\" \"c\" \"d\" \"e\" \"f\" \"g\" \"h\" \"i         


        

Answer 1

Probably not the cleanest, but easy to see what's happening:

foo<-letters[1:26]
outlen <- 73 # or whatever length you want
 oof <- vector(len=26)
for ( j in 2:(outlen%/%26)) {
    for (k in 1:26) oof[k] <- paste(rep(letters[k],j),sep='',collapse='')
    foo<-c(foo,oof)
}
for (jj in 1:(outlen%%26) ) foo[(26*j)+jj]<-paste(rep(letters[jj],(j+1)),sep='',collapse='')

foo
[1] "a"   "b"   "c"   "d"   "e"   "f"   "g"   "h"   "i"   "j"   "k"   "l"   "m"   "n"  
[15] "o"   "p"   "q"   "r"   "s"   "t"   "u"   "v"   "w"   "x"   "y"   "z"   "aa"  "bb" 
[29] "cc"  "dd"  "ee"  "ff"  "gg"  "hh"  "ii"  "jj"  "kk"  "ll"  "mm"  "nn"  "oo"  "pp" 
[43] "qq"  "rr"  "ss"  "tt"  "uu"  "vv"  "ww"  "xx"  "yy"  "zz"  "aaa" "bbb" "ccc" "ffffd"
[57] "eee" "fff" "ggg" "hhh" "iii" "jjj" "kkk" "lll" "mmm" "nnn" "ooo" "ppp" "qqq" "rrr"
[71] "sss" "ttt" "uuu"

EDIT: Matthew wins, hands-down:

microbenchmark(anandaLetters(5000),matthewletters(5000),carlletters(5000),times=10)
Unit: milliseconds
                 expr       min        lq     median        uq        max neval
  anandaLetters(5000) 85.339200 85.567978 85.9827715 86.260298  86.612231    10
 matthewletters(5000)  3.413706  3.503506  3.9067535  3.946950   4.106453    10
    carlletters(5000) 94.893983 95.405418 96.4492430 97.234784 110.681780    10