gsub return an empty string when no match is found

Question

I\'m using the gsub function in R to return occurrences of my pattern (reference numbers) on a list of text. This works great unless no match is found, in whic

Answer 1

Another simple way is to use gsub but specify you want '' in a new function

noFalsePositives <- function(a,b,x) {
  return(ifelse(gsub(a,b,x)==x,'',gsub(a,b,x)))
}
# usage
noFalsePositives(".*(Ref. (\\d+)).*", "\\1", data)
# [1] "Ref. 12" ""