Envelope of Geometry
Function calculates the rectangular bounding box for the given geometry
gEnvelope(spgeom, byid=FALSE, id = NULL)
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) |
id |
Character vector defining id labels for the resulting geometries, if unspecified returned geometries will be labeled based on their parent geometries' labels. |
Returns the rectangular bounding box as a SpatialPolygons object. If spgeom is a degenerate case (horizontal/vertical line, single point) then the function may return an object with lower dimension (SpatialLines or SpatialPoints) or an invalid polygon.
Roger Bivand & Colin Rundel
x = readWKT(paste("POLYGON((0 40,10 50,0 60,40 60,40 100,50 90,60 100,60",
"60,100 60,90 50,100 40,60 40,60 0,50 10,40 0,40 40,0 40))"))
env = gEnvelope(x)
plot(x,col='blue',border='blue')
plot(env,add=TRUE)
#Degenerate Cases
gEnvelope(readWKT("POINT(1 1)")) #returns SpatialPoints
gEnvelope(readWKT("LINESTRING(1 1,1 2)")) #invalid polygon
gEnvelope(readWKT("LINESTRING(1 1,2 1)")) #invalid polygonPlease choose more modern alternatives, such as Google Chrome or Mozilla Firefox.