list files recursive up to a certain level in R

Question

Is there an elegant way to list files recursive up to a certain level? I have a very complicated folder structure und it takes several seconds to search for all xml

Answer 1

Here is a way using Sys.glob:

getFiles <- function(ext, depth){
  wildcards <- Reduce(
    file.path, x = rep("*", depth), init = paste0("*.", ext),
    right = TRUE, accumulate = TRUE
  )
  Sys.glob(wildcards)
}
getFiles("xml", 4)

Answer 2

For elegance, I would write a small recursive utility with an n parameter that you can use afterwards. E.g. something like:

list.dirs.depth.n <- function(p, n) {
  res <- list.dirs(p, recursive = FALSE)
  if (n > 1) {
    add <- list.dirs.depth.n(res, n-1)
    c(res, add)
  } else {
    res
  }
}

list.dirs.depth.n(".", n = 3)

And then use this in your call to list.files