rasterToPolygons function

Raster to polygons conversion

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).

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}

Returns

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')