misc-gArea.Rd
Calculates the area of the given geometry.
gArea(spgeom, byid=FALSE)
sp object as defined in package sp
Logical determining if the function should be applied across subgeometries (TRUE) or the entire object (FALSE)
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.
gArea(readWKT("POINT(1 1)"))
#> [1] 0
gArea(readWKT("LINESTRING(0 0,1 1,2 2)"))
#> [1] 0
gArea(readWKT("LINEARRING(0 0,3 0,3 3,0 3,0 0)"))
#> [1] 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)
#> [1] 9
p1@polygons[[1]]@area
#> [1] 9
gArea(p2)
#> [1] 8
p2@polygons[[1]]@area
#> [1] 9