boundaries: boundaries (edges) detection

In raster: Geographic Data Analysis and Modeling

boundaries (edges) detection

Description

Detect boundaries (edges). boundaries 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

## S4 method for signature 'RasterLayer'
boundaries(x, type='inner', classes=FALSE, directions=8, asNA=FALSE, filename="", ...)

Arguments

x	RasterLayer object
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)
asNA	logical. If TRUE, non-edges are returned as NA instead of zero
filename	character. Filename for the output RasterLayer (optional)
...	additional arguments as for writeRaster

Value

RasterLayer. Cell values are either 1 (a border) or 0 (not a border), or NA

See Also

focal, clump

Examples

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

raster documentation built on April 4, 2025, 5:34 a.m.