dismo (version 1.3-14)

Voronoi Hull: Voronoi hull model

Description

Voronoi polygons for presence/absence data

Usage

# S4 method for matrix,matrix
voronoiHull(p, a, ext=NULL, dissolve=FALSE, crs=NA, ...)
# S4 method for data.frame,data.frame
voronoiHull(p, a, ext=NULL, dissolve=FALSE, crs=NA, ...)
# S4 method for SpatialPoints,SpatialPoints
voronoiHull(p, a, ext=NULL, dissolve=FALSE, ...)

Value

A VoronoiHull object (inherits from DistModel-class)

Arguments

p

Presence points. Two column matrix, data.frame, or a SpatialPoints* object

a

Absence points. Must be of the same class as p

ext

Extent to limit or expand the area of interest

dissolve

Boolean. Dissolve (aggregate) polygons?

crs

character or CRS object. PROJ.4 notation coordinate reference system

...

Additional arguments passed to voronoi

Author

Robert J. Hijmans

See Also

convHull, voronoi

Examples

r <- raster(system.file("external/rlogo.grd", package="raster"))
# presence points
p <- matrix(c(17, 42, 85, 70, 19, 53, 26, 84, 84, 46, 48, 85, 4, 95, 48, 54, 66, 74, 50, 48, 
      28, 73, 38, 56, 43, 29, 63, 22, 46, 45, 7, 60, 46, 34, 14, 51, 70, 31, 39, 26), ncol=2)

# absence points
a <- matrix(c(30, 23, 5, 5, 31, 33, 91, 63, 60, 88, 93, 97, 65, 68, 85, 97, 35, 32, 29, 55,
      3, 8, 19, 71, 49, 36, 69, 41, 20, 28, 18, 9, 5, 9, 25, 71, 8, 32, 46, 60), ncol=2)

v <- voronoiHull(p, a)
	  
x <- predict(r, v)

if (FALSE) {
plot(x)
points(p, col='black', pch=20, cex=2)
points(a, col='red', pch=20, cex=2)
}