rgeos (version 0.6-4)

gArea: Area of Geometry

Description

Calculates the area of the given geometry.

Usage

gArea(spgeom, byid=FALSE)

Value

Returns the area of the geometry in the units of the current projection. By definition non-[MULTI]POLYGON geometries have an area of 0. The area of a POLYGON is the area of its shell less the area of any holes. Note that this value may be different from the area slot of the Polygons class as this value does not subtract the area of any holes in the geometry.

Arguments

spgeom

sp object as defined in package sp

byid

Logical determining if the function should be applied across subgeometries (TRUE) or the entire object (FALSE)

Author

Roger Bivand & Colin Rundel

See Also

gLength

Examples

	gArea(readWKT("POINT(1 1)"))
	gArea(readWKT("LINESTRING(0 0,1 1,2 2)"))
	gArea(readWKT("LINEARRING(0 0,3 0,3 3,0 3,0 0)"))
	
	
	p1 = readWKT("POLYGON((0 0,3 0,3 3,0 3,0 0))")
	p2 = readWKT("POLYGON((0 0,3 0,3 3,0 3,0 0),(1 1,2 1,2 2,1 2,1 1))")
	
	gArea(p1)
	p1@polygons[[1]]@area
	
	gArea(p2)
	p2@polygons[[1]]@area