rasterToPolygons: Raster to polygons conversion

In raster: Geographic Data Analysis and Modeling

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

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