R/extract_dist.R

In quaxnat: Estimation of Natural Regeneration Potential

##############################################################################
#' Extracting distances to nearest seed source for point data
#'
#' @description Extracts a distance for the inventory plots. The distance to the
#'  nearest seed source is used for the analysis of the regeneration potential.
#'
#' @param raster Raster dataset with tree species classification of specific
#'  tree species and tree species groups.
#' @param geom Geodata representing the study area. This can be a polygon
#'  or point dataset. This describes the outer boundary of the study area.
#'  A buffer of 1000 m is placed around the Bounding box to possibly take into
#'  account seed trees outside the study area.
#' @param species Represents the numerical value by which the tree species
#'  of interest was encoded in the raster dataset.
#'
#' @return Numeric vector with distances of every inventory plot to the
#'  nearest seed source of a specific tree species.
#'
#' @export
#'
#' @examples
#' ## Create raster data set
#' set.seed(2023)
#' rr <- terra::rast(
#' matrix(sample(0:10, 20 * 20, replace = TRUE),
#'         nrow = 20, ncol = 20))
#'
#' ## Create vector data set
#' vec <- terra::vect(rbind(c(5,10), c(5,15)))
#'
#' ## Extract distance for the inventory plot
#' extract_dist(raster=rr, geom=vec, species="10")

extract_dist <- function(raster, geom, species){
  extract <- terra::extract(seed_tree_distmap(raster, species), geom)[,2]
  return(extract)
}

# Old Implementation
#extract_dist <- function(raster, geom, species){
#  extract <- terra::extract(seed_tree_distmap(raster, geom, species), geom)[,2]
#  return(extract)
#}