Detect boundaries (edges)

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 SpatRaster
boundaries(x, classes=FALSE, inner=TRUE, 
         directions=8, falseval=0, filename="", ...)

Arguments

x

SpatRaster

inner

logical. If TRUE, "inner" boundaries are returned, else "outer" boundaries are returned

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)

falseval

numeric. The value to use for cells that are not a boundary and not NA

filename

character. Output filename

...

options for writing files as in writeRaster

Value

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

See also

focal, patches

Examples

r <- rast(nrows=18, ncols=36, xmin=0)
r[150:250] <- 1
r[251:450] <- 2
bi <- boundaries(r)
bo <- boundaries(r, inner=FALSE)
bc <- boundaries(r, classes=TRUE)
#plot(bc)