Using a loop/anything else to write a string of intervals (vector)

Question

I did this the hard way and would like to know how you would do it with a loop/faster method. I'm creating labels for levels to use in a cut statement, working with age groups.

levels(age_group) <- ("<10","10-19","20-29","30-39","40-49","50-59","60-69","70-79","80-89","90-99","100-109",
             "110-119","120-129","130+")

Does anyone have any good ideas about how to do this? The less "<10" and "130+" can be added manually but I'm sure there is a faster way to do the rest.

Thanks

Answer 1

It would probably be best to use the levels generated by cut, because your current intervals don't define which end is included.

s <- c(-Inf,seq(10,130,10),Inf)
levels(cut(s,s))
#  [1] "(-Inf,10]"  "(10,20]"    "(20,30]"    "(30,40]"    "(40,50]"   
#  [6] "(50,60]"    "(60,70]"    "(70,80]"    "(80,90]"    "(90,100]"  
# [11] "(100,110]"  "(110,120]"  "(120,130]"  "(130, Inf]"

If you must use your current intervals, you can use this simple function:

strInterval <- function(start, end, by) {
  s <- seq(start, end, by)
  i <- paste(head(s,-1), s[-1]-1, sep="-")
  c(paste0("<",start), i, paste0(end,"+"))
}
strInterval(10,130,10)
#  [1] "<10"     "10-19"   "20-29"   "30-39"   "40-49"   "50-59"   "60-69"  
#  [8] "70-79"   "80-89"   "90-99"   "100-109" "110-119" "120-129" "130+"