raster: boundaries – R documentation

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boundaries

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

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

Geographic Data Analysis and Modeling

v3.4-10

GPL (>= 3)

Authors

Robert J. Hijmans [cre, aut] (<https://orcid.org/0000-0001-5872-2872>), Jacob van Etten [ctb], Michael Sumner [ctb], Joe Cheng [ctb], Dan Baston [ctb], Andrew Bevan [ctb], Roger Bivand [ctb], Lorenzo Busetto [ctb], Mort Canty [ctb], Ben Fasoli [ctb], David Forrest [ctb], Aniruddha Ghosh [ctb], Duncan Golicher [ctb], Josh Gray [ctb], Jonathan A. Greenberg [ctb], Paul Hiemstra [ctb], Kassel Hingee [ctb], Institute for Mathematics Applied Geosciences [cph], Charles Karney [ctb], Matteo Mattiuzzi [ctb], Steven Mosher [ctb], Babak Naimi [ctb], Jakub Nowosad [ctb], Edzer Pebesma [ctb], Oscar Perpinan Lamigueiro [ctb], Etienne B. Racine [ctb], Barry Rowlingson [ctb], Ashton Shortridge [ctb], Bill Venables [ctb], Rafael Wueest [ctb]

Initial release

2021-05-02