as.polygons {terra}

Conversion to a SpatVector of polygons

Description

Conversion of a SpatRaster, SpatVector or SpatExtent to a SpatVector of polygons.

Usage

## S4 method for signature 'SpatRaster'
as.polygons(x, round=TRUE, aggregate=TRUE, values=TRUE,
		na.rm=TRUE, na.all=FALSE, extent=FALSE, digits=0, ...)

## S4 method for signature 'SpatVector'
as.polygons(x, extent=FALSE)

## S4 method for signature 'SpatExtent'
as.polygons(x, crs="")

Arguments

x

SpatRaster, SpatVector or SpatExtent

round

logical; If TRUE and aggregate=TRUE, values are rounded before aggregation. If this value is FALSE the SpatVector returned can have very many polygons and can be very large

aggregate

logical; combine cells with the same values? If TRUE only the first layer in x is processed

values

logical; include cell values as attributes?

extent

logical. if TRUE, a polygon for the extent of the SpatRaster or SpatVector is returned. If x is a SpatRaster, the polygon has vertices for each row and column, not just the four corners of the raster. This can be useful for more precise projection. If that is not required, it is more efficient to get the extent represented by only the four corners with as.polygons(ext(x), crs=crs(x))

na.rm

logical. If TRUE cells that are NA are ignored

na.all

logical. If TRUE cells are only ignored if na.rm=TRUE and their value is NA for all layers instead of for any layer

digits

integer. The number of digits for rounding (if round=TRUE)

crs

character. The coordinate reference system (see crs)

...

additional arguments. For backward compatibility. Will be removed in the future

Value

SpatVector

See Also

as.lines, as.points

Examples

r <- rast(ncols=2, nrows=2)
values(r) <- 1:ncell(r)

if  (gdal() >= "3.0.0") {
	p <- as.polygons(r)
	p
}