Repeating Vector of Letters

repeating vector of letters

It's not too difficult to piece together a quick function to do something like this:

myLetters <- function(length.out) {
  a <- rep(letters, length.out = length.out)
  grp <- cumsum(a == "a")
  vapply(seq_along(a), 
         function(x) paste(rep(a[x], grp[x]), collapse = ""),
         character(1L))
}
myLetters(60)
#  [1] "a"   "b"   "c"   "d"   "e"   "f"   "g"   "h"   "i"   "j"   "k"   "l"  
# [13] "m"   "n"   "o"   "p"   "q"   "r"   "s"   "t"   "u"   "v"   "w"   "x"  
# [25] "y"   "z"   "aa"  "bb"  "cc"  "dd"  "ee"  "ff"  "gg"  "hh"  "ii"  "jj" 
# [37] "kk"  "ll"  "mm"  "nn"  "oo"  "pp"  "qq"  "rr"  "ss"  "tt"  "uu"  "vv" 
# [49] "ww"  "xx"  "yy"  "zz"  "aaa" "bbb" "ccc" "ddd" "eee" "fff" "ggg" "hhh"

Repeating a vector of names in a column over each date

Don't use map; you can take advantage of vector recycling. Just repeat each element of date_range 4 times.

DF <- data.frame(date = rep(date_range, each = 4), 
                 Source = c("a", "b", "c", "d"))

head(DF)
          date Source
1   2015-01-01      a
2   2015-01-01      b
3   2015-01-01      c
4   2015-01-01      d
5   2015-02-01      a
6   2015-02-01      b
7   2015-02-01      c
8   2015-02-01      d
9   2015-03-01      a
10  2015-03-01      b

Another option with tidyr::separate_rows:

library(tidyr)
data.frame(date = date_range, Source = c("a,b,c,d")) %>% 
  separate_rows(Source)

Generate vector of a repeated string with incremental suffix number

An alternative to paste is sprintf, which can be a bit more convenient if, for instance, you wanted to "pad" your digits with leading zeroes.

Here's an example:

sprintf("Fst%d", 1:10)     ## No padding
# [1] "Fst1"  "Fst2"  "Fst3"  "Fst4"  "Fst5"  
# [6] "Fst6"  "Fst7"  "Fst8"  "Fst9"  "Fst10"
sprintf("Fst%02d", 1:10)   ## Pads anything less than two digits with zero
# [1] "Fst01" "Fst02" "Fst03" "Fst04" "Fst05" 
# [6] "Fst06" "Fst07" "Fst08" "Fst09" "Fst10"

So, for your question, you would be looking at:

sprintf("Fst%d", 1:100) ## or sprintf("Fst%03d", 1:100)

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