raster: rasterToPolygons – R documentation

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rasterToPolygons

Raster to polygons conversion

Description

Raster to polygons conversion. Cells with NA are not converted. A function can be used to select a subset of the raster cells (by their values).

Usage

rasterToPolygons(x, fun=NULL, n=4, na.rm=TRUE, digits=12, dissolve=FALSE)

Arguments

`x`	Raster* object
`fun`	function to select a subset of raster values (only allowed if `x` has a single layer)
`n`	integer. The number of nodes for each polygon. Only 4, 8, and 16 are allowed
`na.rm`	If `TRUE`, cells with `NA` values in all layers are ignored
`digits`	number of digits to round the coordinates to
`dissolve`	logical. If `TRUE`, polygons with the same attribute value will be dissolved into multi-polygon regions. This option requires the rgeos package

Details

fun should be a simple function returning a logical value.

E.g.: fun=function(x){x==1} or fun=function(x){x>3 & x<6}

Value

SpatialPolygonsDataFrame

Examples

r <- raster(nrow=18, ncol=36)
values(r) <- runif(ncell(r)) * 10
r[r>8] <- NA
pol <- rasterToPolygons(r, fun=function(x){x>6})

#plot(r > 6)
#plot(pol, add=TRUE, col='red')

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