raster (version 2.1-41)

edge: Edge detection

Description

Detect edges. Edges are cells that have more than one class in the 4 or 8 cells surrounding it, or, if classes=FALSE, cells with values and cells with NA.

Usage

## S3 method for class 'RasterLayer':
edge(x, filename="", type='inner', classes=FALSE, directions=8, ...)

Arguments

x

RasterLayer object

filename

Character. Filename for the output RasterLayer (optional)

type

Character. 'inner', or 'outer'

classes

Character. Logical. If TRUE all different values are (after rounding) distinguished, as well as NA. If FALSE (the default) only edges between NA and non-NA cells are considered

directions

Integer. Which cells are considered adjacent? Should be 8 (Queen's case) or 4 (Rook's case)

...

Additional arguments as for writeRaster

Value

• RasterLayer. Cell values are either 1 (and edge) or 0 (not an edge), or NA

See Also

focal, clump

Examples

r <- raster(nrow=18, ncol=36, xmn=0)
r[150:250] <- 1
r[251:450] <- 2
plot( edge(r, type='inner') )
plot( edge(r, type='outer') )
plot( edge(r, classes=TRUE) )