fixes #986)

rspatial · Jan 27, 2023 · 8ff8a2f · 8ff8a2f
1 parent f2f4007
commit 8ff8a2f
Show file tree

Hide file tree

Showing 2 changed files with 34 additions and 4 deletions.
diff --git a/R/rasterize.R b/R/rasterize.R
@@ -152,7 +152,23 @@ rasterize_points <- function(x, y, field, values, fun="last", background=NA, upd
 
 
 setMethod("rasterize", signature(x="matrix", y="SpatRaster"),
-	function(x, y, values=1, fun, ..., background=NA, update=FALSE, filename="", overwrite=FALSE, wopt=list()) {
+	function(x, y, values=1, fun, ..., background=NA, update=FALSE, by=NULL, filename="", overwrite=FALSE, wopt=list()) {
+
+		if (!is.null(by)) {
+			by <- rep_len(by, nrow(x))
+			values <- rep_len(values, nrow(x))
+
+			x <- lapply(split(data.frame(x), by), as.matrix)
+			values <- split(values, by)
+
+			out <- rast(lapply(1:length(x), function(i) rasterize(x[[i]], y, values[[i]], fun, background=background, update=update)))
+			names(out) <- unique(by)
+			if (filename != "") {
+				out <- writeRaster(out, filename, overwrite=overwrite, wopt=wopt)
+			}
+			return(out)
+		}
+
 		lonlat <- .checkXYnames(colnames(x))
 
 		if (NCOL(values) <= 1) {
@@ -177,7 +193,19 @@ setMethod("rasterize", signature(x="matrix", y="SpatRaster"),
 
 
 setMethod("rasterize", signature(x="SpatVector", y="SpatRaster"),
-	function(x, y, field="", fun, ..., background=NA, touches=FALSE, update=FALSE, sum=FALSE, cover=FALSE, filename="", overwrite=FALSE, wopt=list()) {
+	function(x, y, field="", fun, ..., background=NA, touches=FALSE, update=FALSE, sum=FALSE, cover=FALSE, by=NULL, filename="", overwrite=FALSE, wopt=list()) {
+
+
+		if (!is.null(by)) {
+			uby <- unlist(unique(x[[by]]))
+			x <- split(x, by)
+			out <- rast(lapply(x, function(i) rasterize(i, y, field=field, fun, background=background, touches=touches, update=update, sum=sum, cover=cover)))
+			names(out) <- uby
+			if (filename != "") {
+				out <- writeRaster(out, filename, overwrite=overwrite, wopt=wopt)
+			}
+			return(out)
+		}
 
 		values <- 1
 		if (!is.character(field)) {

diff --git a/man/rasterize.Rd b/man/rasterize.Rd
@@ -15,10 +15,10 @@ Transfer values associated with the geometries of vector data to a raster
 
 \usage{
 \S4method{rasterize}{SpatVector,SpatRaster}(x, y, field="", fun, ..., background=NA, touches=FALSE,
-	update=FALSE, sum=FALSE, cover=FALSE, filename="", overwrite=FALSE, wopt=list())
+	update=FALSE, sum=FALSE, cover=FALSE, by=NULL, filename="", overwrite=FALSE, wopt=list())
 
 \S4method{rasterize}{matrix,SpatRaster}(x, y, values=1, fun, ..., background=NA, 
-	update=FALSE, filename="", overwrite=FALSE, wopt=list())
+	update=FALSE, by=NULL, filename="", overwrite=FALSE, wopt=list())
 }
 
 \arguments{
@@ -43,6 +43,8 @@ Transfer values associated with the geometries of vector data to a raster
 
   \item{cover}{logical. If \code{TRUE} and the geometry of \code{x} is polygons, the fraction of a cell that is covered by the polygons is returned. This is estimated by determining presence/absence of the polygon in at least 100 sub-cells (more of there are very few cells)} 
 
+  \item{by}{character or numeric value(s) to split \code{x} into multiple groups. There will be a separate layer for each group returned. If \code{x} is a SpatVector, \code{by} can be a column number or name. If \code{x} is a matrix, \code{by} should be a vector that identifies group membership for each row in \code{x}}
+
   \item{filename}{character. Output filename}
   \item{overwrite}{logical. If \code{TRUE}, \code{filename} is overwritten}  
   \item{wopt}{list with additional arguments for writing files as in \code{\link{writeRaster}}}