raster (version 1.8-3)

gridDistance: Grid distance

Description

The function calculates the distance to cells of a RasterLayer when the path has to follow the center of neighboring raster cells (currently only implemented as a 'queen' case). The distance is in meters if the RasterLayer is not projected (+proj=longlat) and in map units (typically meters) when it is projected. Distances are calculated by summing local distances between cells, which are connected with their neighbours in 8 directions.

Usage

gridDistance(x, origin, omit=NULL, filename="", ...)

Arguments

x

a RasterLayer object

origin

value(s) of the cells from which the distance is calculated

omit

value(s) of the cells which cannot be traversed (optional)

filename

character. output filename (optional)

...

additional arguments. See Details.

Value

• A RasterLayer object

Details

The following additional arguments can be passed, to replace default values for this function rll{ overwrite Logical. If TRUE, "filename" will be overwritten if it exists format Character. Output file type. See writeRaster datatype Character. Output data type. See dataType progress Character. "text", "window", or "" (the default, no progress bar) }

See Also

See distance for 'as the crow flies' distance. Additional distance measures and options (directions, cost-distance) are available in the 'gdistance' package that is available on R-Forge

Examples

#world lonlat raster
r <- raster(ncol=10,nrow=10)
r[] <- 1
r[48] <- 2
r[66:68] <- 3
distRaster <- gridDistance(r,origin=2,omit=3) 
plot(distRaster)

#UTM small area
projection(r) <- "+proj=utm +zone=15 +ellps=GRS80 +datum=NAD83 +units=m +no_defs"
distRaster <- gridDistance(r,origin=2,omit=3) 
plot(distRaster)