tmap (version 1.6)

poly_to_raster: Convert spatial polygons to a raster

Description

Convert spatial polygons to a raster. The value of each raster cell will be the polygon ID number. Alternatively, if copy.data, the polygon data is appended to each raster cell.

Usage

poly_to_raster(shp, nrow = NA, ncol = NA, N = 250000, use.cover = FALSE, copy.data = FALSE, to.Raster = !copy.data, ...)

Arguments

shp

shape object. Either a SpatialPoints(DataFrame) or a SpatialGrid(DataFrame).

nrow

number of raster rows. If NA, it is automatically determined by N and the aspect ratio of shp.

ncol

number of raster columns. If NA, it is automatically determined by N and the aspect ratio of shp.

N

preferred number of raster cells.

use.cover

logical; should the cover method be used? This method determines per raster cell which polygon has the highest cover fraction. This method is better, but very slow, since N times the number of polygons combinations are processed (using the getCover argument of rasterize). By default, when a raster cell is covered by multiple polygons, the last polygon is taken (see fun argment of rasterize))

copy.data

should the polygon data be appended to the raster? Only recommended when N is small.

to.Raster

logical; should the output be a Raster object (TRUE), or a SpatialGridDataFrame (FALSE). If TRUE, a RasterBrick is returned when by is specified, and a RasterLayer when by is unspecified. For very large rasters, use TRUE, since large Raster objects are accessed from disk.

...

arguments passed on to rasterize

Value

A SpatialGridDataFrame, or a Raster object when (to.Raster=TRUE)

See Also

points_to_raster

Examples

## Not run: 
# 	data(NLD_muni)
# 	
# 	# choropleth of 65+ population percentages
# 	qtm(NLD_muni, fill="pop_65plus", format="NLD")
# 	
# 	# rasterized version
# 	NLD_rst <- poly_to_raster(NLD_muni, copy.data = TRUE)
# 	qtm(NLD_rst, raster="pop_65plus", format="NLD")
# ## End(Not run)