if an output is logical(0) skip the current iteration and move on to the next in R

I have a for loop in R. Inside the for loop I have

kl<-stri_detect_fixed(nn, "new")

In some cases, kl is logical(0). If this is the case I want to skip the current iteration and move on to the next in R.

I tried something like

if (is.logical(kl)==T) {
next
}

but is does not work. Any ideas?

Many thanks

Solution

Return value of stringi::stri_detect_fixed() is a logical vector, so is.logical(kl) is always TRUE.
But you can test if its length is 0:

lst <- list(a = c("foo", "bar"),
            b = NULL,
            c = "news")

for (nn in lst){
  kl <- stringi::stri_detect_fixed(nn, "new")
  if (length(kl) < 1) next
  message("no skip for ", paste(nn, collapse = ", "))
}
#> no skip for foo, bar
#> no skip for news

Or if input is NULL:

for (nn in lst){
  if (is.null(nn)) next
  kl <- stringi::stri_detect_fixed(nn, "new")
  message("no skip for ", paste(nn, collapse = ", "))
}
#> no skip for foo, bar
#> no skip for news

^{Created on 2024-09-21 with reprex v2.1.1}