R/split_on_poly.R

In choisy/sptools: Additional Functions for Spatial* Objects

#' Splits a raster on a spatial polygon
#'
#' This function combines the above functions \code{\link[sptools]{as_list}} and
#' \code{\link[sptools]{crop_on_poly}}. to split a \code{RasterLayer} object on
#' the features of a \code{SpatialPpolygons*} object. Of course, the
#' \code{RasterLayer} and the \code{SpatialPpolygons*} objects need to
#' superpose.
#'
#' @param rstr A RasterLayer
#' @param plgns A SpatialPolygon* object
#'
#' @return A list of \code{RasterLayer} objects.
#'
#' @export
#'
#' @examples
#' library(worldpopVN)
#'
#' provinces <- sptools::gadm("vietnam", "sp", 1, intlib = FALSE, save = TRUE)
#' ppp2010 <- worldpopVN::getpop(2010)
#' class(ppp2010)
#'
#' ppp2010_split <- split_on_poly(ppp2010, provinces[1:3, ])
#' class(ppp2010_split)
#' table(sapply(ppp2010_split, class))
split_on_poly <- function(rstr, plgns) {
  plgns <- as_list(plgns)
  plgns <- lapply(plgns, function(x) crop_on_poly(rstr, x))
}