Retrieve (get_layer.R)

[rellimylime]

get_layer.R is the retrieval layer for the package. It fetches data via the STAC given user specifications.

get_layer() validates inputs, checks the layer exists in the catalog, confirms it is hosted, then reads it through GDAL /vsicurl/ for COG streaming. If a bounding box is supplied, it transforms the bbox to the COG's native raster CRS (EPSG 5070) and crops before returning a SpatRaster.

The function also wraps retrieval in tryCatch so errors are returned with the layer id and URL for easier debugging.

• get_layer()
  

  fedex/R/get_layer.R

  Lines 1 to 47 in f191448

  	#' Retrieve a WRI layer as raster
  	#'
  	#' Download and optionally crop a WRI layer to a bounding box. For hosted layers,
  	#' this uses COG streaming to fetch only the requested spatial subset.
  	#'
  	#' @param id Character. Layer name (without .tif extension). Use `list_layers()`
  	#' to see available layers.
  	#' @param bbox Numeric vector of length 4, optional. Bounding box as c(xmin, ymin, xmax, ymax)
  	#' in EPSG:4326 (longitude/latitude). If NULL, returns the full raster.
  	#'
  	#' @returns A terra SpatRaster object, optionally cropped to the bounding box
  	#' @export
  	#'
  	#' @examples
  	#' # Get the full WRI score layer
  	#' wri_full <- get_layer("WRI_score")
  	#' terra::plot(wri_full)
  	#'
  	#' # Get WRI score for northern California
  	#' bbox_norcal <- c(-122, 37, -121, 38)
  	#' wri_norcal <- get_layer("WRI_score", bbox = bbox_norcal)
  	#' terra::plot(wri_norcal)
  	#'
  	#' # Get an air quality resistance indicator
  	#' asthma <- get_layer("air_quality_resistance_asthma", bbox = bbox_norcal)
  	#' terra::plot(asthma)
  	get_layer <- function(id, bbox = NULL) {
  	# Validate inputs
  	if (missing(id) || is.null(id) || id == "") {
  	stop("Layer 'id' is required. Use list_layers() to see available layers.")
  	}
  	if (!is.null(bbox) && length(bbox) != 4) {
  	stop("'bbox' must be a numeric vector of length 4: c(xmin, ymin, xmax, ymax)")
  	}
  	# Get all layers and find the matching one
  	all_layers <- list_layers()
  	if (!id %in% all_layers$id) {
  	stop(
  	"Layer '", id, "' not found in STAC catalog.\n",
  	"Available layers: ", paste(head(all_layers$id, 10), collapse = ", "),
  	if (nrow(all_layers) > 10) "..." else ""
  	)
  	}

@FlukeAndFeather