selecting path elements by position

[Tazinho]

I just needed to select some path elements by position and thought this should be provided by fs.

Sth. like (maybe also vectorized over path):

library(fs)

path_select <- function(path, seq, from = c("start", "end")) {
  
  from <- match.arg(from)
  
  if (length(path) > 1) {stop("Please supply only one path.")}
  
  path <- unlist(fs::path_split(path))
  path_seq <- seq_along(path)
  
  if (max(seq) > length(path)) {stop("`seq` contains a higher number than the path has elements.")}
  
  if (from == "start") {path <- path[seq]}
  if (from == "end") {
    path_seq <- rev(rev(path_seq)[seq])
    path <- path[path_seq]
  }
  
  path <- fs::path_join(path)
  
  return(path)
}

path <- path("some", "simple", "path", "to", "a", "file.txt")

path_select(path, 1:3)
#> some/simple/path
path_select(path, 1:3, "end")
#> to/a/file.txt
path_select(path, -1, "end")
#> some/simple/path/to/a
path_select(path, 3:4)
#> path/to

^{Created on 2021-04-19 by the reprex package (v0.3.0)}

[gaborcsardi]

Are you interested in submitting a PR?