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#' PLAND (class level)
#'
#' @description Percentage of landscape of class (Area and Edge metric)
#'
#' @param landscape A categorical raster object: SpatRaster; Raster* Layer, Stack, Brick; stars or a list of SpatRasters.
#' @param directions The number of directions in which patches should be
#' connected: 4 (rook's case) or 8 (queen's case).
#'
#' @details
#' \deqn{PLAND = \frac{\sum \limits_{j = 1}^{n} a_{ij}} {A} * 100}
#' where \eqn{a_{ij}} is the area of each patch and \eqn{A} is the total
#' landscape area.
#'
#' PLAND is an 'Area and edge metric'. It is the percentage of the landscape
#' belonging to class i. It is a measure of composition and because of the relative
#' character directly comparable among landscapes with different total areas.
#'
#' Because the metric is based on distances or areas please make sure your data
#' is valid using \code{\link{check_landscape}}.
#'
#' \subsection{Units}{Percentage}
#' \subsection{Range}{0 < PLAND <= 100}
#' \subsection{Behaviour}{Approaches PLAND = 0 when the proportional class area is decreasing.
#' Equals PLAND = 100 when only one patch is present.}
#'
#' @seealso
#' \code{\link{lsm_c_ca}},
#' \code{\link{lsm_l_ta}}
#'
#' @return tibble
#'
#' @examples
#' landscape <- terra::rast(landscapemetrics::landscape)
#' lsm_c_pland(landscape)
#'
#' @references
#' McGarigal K., SA Cushman, and E Ene. 2023. FRAGSTATS v4: Spatial Pattern Analysis
#' Program for Categorical Maps. Computer software program produced by the authors;
#' available at the following web site: https://www.fragstats.org
#'
#' @export
lsm_c_pland <- function(landscape, directions = 8) {
landscape <- landscape_as_list(landscape)
result <- lapply(X = landscape,
FUN = lsm_c_pland_calc,
directions = directions)
layer <- rep(seq_along(result),
vapply(result, nrow, FUN.VALUE = integer(1)))
result <- do.call(rbind, result)
tibble::add_column(result, layer, .before = TRUE)
}
lsm_c_pland_calc <- function(landscape, directions, resolution, extras = NULL){
if (missing(resolution)) resolution <- terra::res(landscape)
if (is.null(extras)){
metrics <- "lsm_c_pland"
landscape <- terra::as.matrix(landscape, wide = TRUE)
extras <- prepare_extras(metrics, landscape_mat = landscape,
directions = directions, resolution = resolution)
}
pland <- lsm_p_area_calc(landscape,
directions = directions,
resolution = resolution,
extras = extras)
# all values NA
if (all(is.na(pland$value))) {
return(tibble::new_tibble(list(level = "class",
class = as.integer(NA),
id = as.integer(NA),
metric = "pland",
value = as.double(NA))))
}
pland <- stats::aggregate(x = pland[, 5], by = pland[, 2], FUN = sum)
pland$value <- pland$value / sum(pland$value) * 100
return(tibble::new_tibble(list(level = rep("class", nrow(pland)),
class = as.integer(pland$class),
id = rep(as.integer(NA), nrow(pland)),
metric = rep("pland", nrow(pland)),
value = as.double(pland$value))))
}
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