R/extract_parallel.R

In juoe/spatialtoolbox: Collection of functions for doing spatial stuff.

#' Paralellized extraction
#'
#' @param instack Raster stack
#' @param samples samples
#' @param ncores Number of cores used for paralellization
#'
#' @return Table with extracted values
#' @export

extract_parallel <- function(x, samples, n_cores){

  x_unstack <- raster::unstack(x)

  cl <- parallel::makeCluster(n_cores)
  doParallel::registerDoParallel(cl)

  ext_list <- foreach::foreach(i = x_unstack,
                                 .packages = "raster") %dopar% {

                                   raster::extract(i, samples)

                                 }

  out <- do.call(cbind, ext_list)
  colnames(out) <- names(x)

  return(out)

}