boundaries function

boundaries (edges) detection

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.

## 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

Returns

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) )