latticeDensity (version 1.2.7)

formLattice: Builds a neighbor structure on the nodes.

Description

formLattice connects all nodes into a neighbor lattice by linking any two nodes that are within 1.5*node_spacing. Typically this will result in links in the E, W, N, S, NE, NW, SE, SW directions. The lattice object is created by the function dnearneigh from spdep.

Usage

formLattice(nodeFillingOutput)

Value

formLatticeOutput object

• EW_locs EW coordinates for use by contour

• NS_locs NS coordinates for use by contour

• nodes Matrix of node locations.

• poly Outer boundary.

• latt Neighbor lattice.

• hole.poly List of hole polygons.

Arguments

nodeFillingOutput

An object, as produced by the function nodeFilling.

Author

Ronald P. Barry

Details

When forming the lattice, the function does not check to see if any node is completely isolated from the rest of the nodes, nor does it check to see that paths exist between all pairs of nodes. Thus the lattice might be disconnected. You can still determine a nonparametric density in this case, but you need to think about whether it makes sense to allow disconnected sublattices. If you wish to connect isolated nodes to the lattice, use the editing function editLattice.

References

Ronald P. Barry, Julie McIntyre. Estimating animal densities and home range in regions with irreg- ular boundaries and holes: A lattice-based alternative to the kernel density estimator. Ecological Modelling 222 (2011) 1666-1672. <doi:10.1016/j.ecolmodel.2011.02.016>

Examples

plot.new()
data(polygon1)
nodeFillingOutput <- nodeFilling(poly=polygon1, node_spacing=0.02)
plot(nodeFillingOutput)
formLatticeOutput <- formLattice(nodeFillingOutput)
plot(formLatticeOutput)
Pointdata <- splancs::csr(polygon1,80)
Pointdata <- Pointdata[Pointdata[,1]<0.5,]
plot(polygon1,type="n")
polygon(polygon1)
points(Pointdata,pch=19)
densityOut <- createDensity(formLatticeOutput,PointPattern=Pointdata,
                           k=20,intensity=FALSE, sparse = TRUE)
plot(densityOut)
homerange(densityOut, percent = 0.95)