R/raster_to_points.R

In r-spatialecology/landscapemetrics: Landscape Metrics for Categorical Map Patterns

#' raster_to_points
#'
#' @description Raster to points
#'
#' @param landscape A categorical raster object: SpatRaster; Raster* Layer, Stack, Brick; stars or a list of SpatRasters.
#' @param return_NA If true, NA cells are also included
#'
#' @details
#' Wrapper around terra::xyFromCell and terra::getValues to get raster_to_points
#' function including NA values
#'
#' @return matrix
#'
#' @examples
#' landscape <- terra::rast(landscapemetrics::landscape)
#' raster_to_points(landscape)
#'
#' @keywords internal
#'
#' @export
raster_to_points <- function(landscape, return_NA = TRUE) {

    landscape <- landscape_as_list(landscape)

    result <- lapply(X = seq_along(landscape), function(x) {

        xyz <- raster_to_points_internal(landscape[[x]], return_NA = return_NA)

        xyz <- cbind(layer = x, xyz)
    })

    result <- do.call(rbind, result)

    return(result)

}

raster_to_points_internal <- function(landscape, return_NA) {

    # preallocate matrix
    xyz <- matrix(data = NA,
                  nrow = terra::ncell(landscape), ncol = 3)

    # get coordinates
    xyz[, c(1, 2)] <- terra::xyFromCell(landscape, cell = 1:terra::ncell(landscape))

    # add values including NA
    xyz[, 3] <- terra::values(landscape, mat = FALSE)

    if (!return_NA) {
        xyz <- xyz[!is.na(xyz[, 3]), ]
    }

    colnames(xyz) <- c("x", "y", "z")

    return(xyz)
}