tmap (version 1.6)

points_to_raster: Bin spatial points to a raster

Description

Bin spatial points to a raster. For each raster cell, the number of points are counted. Optionally, a factor variable can be specified by which the points are counts are split.

Usage

points_to_raster(shp, nrow = NA, ncol = NA, N = 250000, by = NULL, to.Raster = FALSE)

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.

by

name of a data variable which should be a factor. The points are split and counted according to the levels of this factor.

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.

Value

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

Details

This function is a wrapper around rasterize.

See Also

poly_to_raster

Examples

## Not run: 
# 	data(NLD_muni, NLD_prov)
# 	
# 	# sample points (each point represents 1000 people)
# 	NLD_muni_points <- sample_dots(NLD_muni, vars = "population", 
# 								   w=1000, convert2density = TRUE)
# 	
# 	# dot map
# 	tm_shape(NLD_muni_points) + tm_dots()
# 	
# 	# convert points to raster
# 	NLD_rst <- points_to_raster(NLD_muni_points, N = 1e4)
# 	
# 	# plot raster
# 	tm_shape(NLD_rst) +
# 		tm_raster() +
# 	tm_shape(NLD_prov) + 
# 		tm_borders() +
# 	tm_format_NLD() + tm_style_grey()
# ## End(Not run)