Function to get '.vrt' sources?

[dfriend21]

It'd be nice if there were a function to get the sources for a '.vrt' file. Using sources() returns the '.vrt' file itself, as expected, but I'd also like to be able to get the files the '.vrt' points to. For now I've made a function that searches the XML and retrieves the file names, which works fine, but it'd be nice if there were a function for this in terra.

library(terra)
#> terra 1.7.39

r <- rast(system.file("ex/elev.tif", package = "terra"))
r_vrt <- vrt(makeTiles(r, 50, tempfile(fileext = ".tif")))

vrt_sources <- function(r_vrt){
  vrt_xml <- xml2::read_xml(sources(r_vrt))
  vrt_path_nodes <- xml2::xml_find_all(vrt_xml, ".//SourceFilename")
  relativeToVRT <- xml2::xml_attr(vrt_path_nodes, "relativeToVRT")
  relativeToVRT[is.na(relativeToVRT)] <- "0"
  is_relative <- relativeToVRT == "1"
  vrt_paths <- xml2::xml_text(vrt_path_nodes)
  vrt_paths[is_relative] <- paste0(dirname(sources(r)), "/", vrt_paths[is_relative])
  return(vrt_paths)
}
vrt_sources(r_vrt)

^{Created on 2023-08-24 with reprex v2.0.2}

[rhijmans]

I have cobbled something together:

terra::vrt_tiles(r_vrt)
#[1] "c:\\temp\\Rtmp4gamPX\\file5ffc75b233e21.tif"
#[2] "c:\\temp\\Rtmp4gamPX\\file5ffc75b233e22.tif"
#[3] "c:\\temp\\Rtmp4gamPX\\file5ffc75b233e23.tif"
#[4] "c:\\temp\\Rtmp4gamPX\\file5ffc75b233e24.tif"

[dfriend21]

Great, thanks!