R: Raster to polygons conversion

rasterToPolygons {raster} | R Documentation

## 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')

[Package raster version 3.4-13 Index]