Centroid of Geometry — gCentroid • rgeos

Function calculates the centroid of the given geometry.

gCentroid(spgeom, byid=FALSE, id = NULL)

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)
id: Character vector defining id labels for the resulting geometries, if unspecified returned geometries will be labeled based on their parent geometries' labels.

Details

Returns a SpatialPoints object of the centroid(s) for spgeom.

Author

Roger Bivand & Colin Rundel

See also

gBoundary gConvexHull gEnvelope gPointOnSurface

Examples


x = readWKT(paste("GEOMETRYCOLLECTION(POLYGON((0 0,10 0,10 10,0 10,0 0)),",
 "POLYGON((15 0,25 15,35 0,15 0)))"))

# Centroids of both the square and circle independently
c1 = gCentroid(x,byid=TRUE) 
# Centroid of square and circle together
c2 = gCentroid(x)

plot(x)
plot(c1,col='red',add=TRUE)
plot(c2,col='blue',add=TRUE)