Modifying hyphenated data with r

Question

I am reading data from a csv file and one of the columns in the data comes in three different formats:

xxxxx-xxx-xx (5-3-2)
xxxxx-xxxx-x (5-4-1)
xxxx-xxxx-xx (4-4-2)

My goal is to turn these three different styles into one style in the form: xxxxx-xxxx-xx (5-4-2)

In order to make all the different forms the same I need to insert an additional zero at the specific location on each of the 3 different conditions like so:

xxxxx-0xxx-xx
xxxxx-xxxx-0x
0xxxx-xxxx-xx

Anyone have thoughts on the best way to accomplish this?

Answer 1

I would do this using sprintf and strsplit:

x <- c('11111-111-11', '11111-1111-1', '1111-1111-11')
y <- strsplit(x, '-')
myfun <- function(y) {
  first <- sprintf('%05d', as.integer(y[1]))
  second <- sprintf('%04d', as.integer(y[2]))
  third <- sprintf('%02d', as.integer(y[3]))

  paste(first, second, third, sep='-')
}

sapply(y, myfun)
# [1] "11111-0111-11" "11111-1111-01" "01111-1111-11"

You could also do this with fancy regular expressions or the gsubfn package but that may be overkill!

Answer 2

Slightly shorter and a more functional programming version of Justin's solution

numbers <- c('11111-111-11', '11111-1111-1', '1111-1111-11')
restyle <- function(number, fmt){
  tmp <- as.list(as.integer(strsplit(number, '-')[[1]]))
  do.call(sprintf, modifyList(tmp, list(fmt = fmt)))
}

sapply(numbers, restyle, fmt = '%05d-%04d-%02d', USE.NAMES = F)