Remove zeros in the start and end of a vector

Question

I have a vector like this:

x <-  c(0, 0, 0, 0, 4, 5, 0, 0, 3, 2, 7, 0, 0, 0)

I want to keep only the elements from position 5 to 11. I w

Answer 1

I would probably define two functions, and compose them:

trim_leading <- function(x, value=0) {
  w <- which.max(cummax(x != value))
  x[seq.int(w, length(x))]
}

trim_trailing <- function(x, value=0) {
  w <- which.max(cumsum(x != value))
  x[seq.int(w)]
}

And then pipe your data through:

x %>% trim_leading %>% trim_trailing