Voronoi Hull {dismo}

Voronoi hull model

Description

Voronoi polygons for presence/absence data

Usage

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

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

Value

A VoronoiHull object (inherits from DistModel-class)

Note

This function is only correct when using a planar coordinate reference system (not longitude/latitude).

Author(s)

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)

## Not run: 
plot(x)
points(p, col='black', pch=20, cex=2)
points(a, col='red', pch=20, cex=2)

## End(Not run)