Create Dummy Layers from Categorical Raster Layers

Given a SpatRaster whose cell values represent categories (e.g., soil types, land use/cover classes), a dummy layer indicating the presence/absence of each category is created, and optionally written on disk. Each category in the raster layer must be represented by a unique integer cell value. Output values indicating the presence or absence of categories in the dummy layers may be set using preval and absval arguments, respectively.

Usage

dummies(
  ca.rast,
  vals = NULL,
  preval = 100,
  absval = 0,
  to.disk = FALSE,
  outdir = ".",
  extension = ".tif",
  ...
)

Arguments

ca.rast

SpatRaster, as in rast. Single-layer SpatRaster whose (integer) cell values represent numeric IDs for categories.

vals

Integer. Vector or sequence of values representing the categories for which dummy layers will be created. If NULL, all categories will be processed. Default: NULL

preval

Integer. Value indicating presence of category. Default: 100

absval

Integer. Value indicating absence of category. Default: 0

to.disk

Boolean. Write output dummy layers to disk? Default: FALSE

outdir

Character. If to.disk = TRUE, string specifying the path for the output dummy raster layers. Default: "."

extension

Character. If to.disk = TRUE, String specifying the extension for the output raster layers (see Details). Default: ".tif"

...

If to.disk = TRUE, additional arguments as for writeRaster.

Value

Single-layer or multi-layer SpatRaster with dummy layer(s).

Details

This function mainly differs from segregate in that presence and absence values can be set arbitrarily, thus allowing for values other than those traditionally used in one-hot/dummy encoding (i.e., 1 and 0).

Please note that the argument extension does not correspond to the argument filetype in writeRaster. However, writeRaster should recognize the appropriate extension for the output raster layers from the extension argument. For instance, by setting extension = ".tif", writeRaster will recognize the extension as GeoTiff, which is the GDAL driver name.

See also

segregate

Other Miscellaneous Functions: figure(), plot3D()

Examples

require(terra)
p <- system.file("exdat", package = "rassta")
# Single-layer SpatRaster of geologic units
f <- list.files(path = p, pattern = "geology2.tif", full.names = TRUE)
geol <- terra::rast(f)
# Dummy layer from geologic unit 1
dums <- dummies(ca.rast = geol, vals = 1, preval = 100, absval = 0)