R/fastData.r

In adamlilith/fasterRaster: Faster Raster and Spatial Vector Processing Using 'GRASS GIS'

#' Get one of the example rasters or spatial vectors
#'
#' This function is a simple way to get example rasters or spatial vector datasets that come with **fasterRaster**.
#'
#' @param x The name of the raster or spatial vector to get. All of these represent a portion of the eastern coast of Madagascar.
#'
#' Spatial vectors (objects of class `sf` from the **sf** package):
#' * [madCoast0]: Outline of the region (polygon)
#' * [madCoast4]: Outlines of the Fokontanies (Communes) of the region (polygons)
#' * [madDypsis]: Records of plants of the genus *Dypsis* (points)
#' * [madRivers]: Major rivers (lines)
#'
#' Rasters (objects of class `SpatRaster` from the **terra** package, saved as GeoTIFF files):
#' * [madChelsa]: Bioclimatic variables
#' * [madCover]: Land cover (also see `madCoverCats`)
#' * [madElev]: Elevation
#' * [madForest2000]: Forest cover in year 2000
#' * [madForest2014]: Forest cover in year 2014
#' * [madLANDSAT]: Surface reflectance in 2023
#' * [madPpt], [madTmin], [madTmax]: Rasters of mean monthly precipitation, and minimum and maximum temperature.
#'
#' Data frames
#' * [appFunsTable]: Table of functions usable by [app()].
#' * [madCoverCats]: Land cover values and categories.
#' * [vegIndices]: Vegetation indices that can be calculated with [vegIndex()].
#'
#' @return A `SpatRaster`, `sf` spatial vector, or a `data.frame`.
#'
#' @example man/examples/ex_fastData.r
#'
#' @export
fastData <- function(x) {

	vectors <- c("madCoast0", "madCoast4", "madDypsis", "madRivers")
	tables <- c("appFunsTable", "madCoverCats", "vegIndices")
	rasters <- c("madChelsa", "madCover", "madElev", "madLANDSAT", "madForest2000", "madForest2014", "madPpt", "madTmin", "madTmax")

	if (!inherits(x, "character")) {
		stop("Please supply the name of an example raster or spatial vector in fasterRaster.")
	} else {
		if (x %in% c(vectors, tables)) {

			madCoast0 <- madCoast4 <- madDypsis <- madRivers <- NULL
			madCoverCats <- NULL

			out <- do.call(utils::data, list(x, envir = environment(), package = "fasterRaster"))
			out <- get(out)

		} else if (x %in% rasters) {
		
			rastFile <- system.file("extdata", paste0(x, ".tif"), package = "fasterRaster")
			out <- terra::rast(rastFile)

			if (x == "madCover") {

			    levs <- system.file("extdata", paste0("madCover.csv"), package = "fasterRaster")
				levs <- utils::read.csv(levs)
				levels(out) <- levs

			}

		} else {
			stop("Please supply the name of a data object available in fasterRaster.")
		}
	}

	out

}