Collapse continuous integer runs to strings of ranges

Question

I have some data in a list that I need to look for continuous runs of integers (My brain thinkrle but don\'t know how to use it here).

It\'s easier to l

Answer 1

Here is an attempt using diff and tapply returning a character vector

runs <- lapply(z, function(x) {
  z <- which(diff(x)!=1); 
  results <- x[sort(unique(c(1,length(x), z,z+1)))]
  lr <- length(results)
  collapse <- rep(seq_len(ceiling(lr/2)),each = 2, length.out = lr)
  as.vector(tapply(results, collapse, paste, collapse = ':'))
  })

runs
$greg
[1] "7:11"  "20:24" "30:33" "49"   

$researcher
[1] "42:48"

$sally
[1] "25:29" "37:41"

$sam
[1] "1:6"   "16:19" "34:36"

$teacher
[1] "12:15"