add rast2colormap

DESCRIPTION

@@ -25,7 +25,7 @@ Suggests:
     rmarkdown,
     covr
 VignetteBuilder: knitr
-RoxygenNote: 7.2.3
+RoxygenNote: 7.3.2
 Roxygen: list(markdown = TRUE)
 Encoding: UTF-8
 Depends: 

NAMESPACE

@@ -25,6 +25,7 @@ export(overlap_fraction)
 export(plot)
 export(rast)
 export(rast2SpatialGrid)
+export(rast2colormap)
 export(rast2poly)
 export(rast_array)
 export(rast_cellId)
@@ -43,6 +44,7 @@ export(st_range)
 export(st_read)
 export(st_rect)
 export(st_write)
+export(value2colormap)
 export(write_shp)
 import(sf)
 importFrom(data.table,as.data.table)

R/tools_rast.R

@@ -73,3 +73,20 @@ rast_dim <- function(f) {
 
   listk(lon, lat)
 }
+
+#' @export
+value2colormap <- function(x, brks, cols) {
+  col2dt <- function(cols) col2rgb(cols) %>% t() %>% as.data.table()
+  colormap = col2dt(cols)
+  ind   = findInterval(x, brks) # %>% summary()
+  colormap[ind, ] |> as.matrix()
+}
+
+#' @export
+rast2colormap <- function(r, brks, cols, fout = "out.tif") {
+  x = values(r)
+  r2 = c(r, r, r)
+  val = value2colormap(x, brks, colors)
+  values(r2) = val
+  writeRaster(r2, fout)
+}