crossvalNparReg: Crossvalidation for non-parametric regression.

In latticeDensity: Density Estimation and Nonparametric Regression on Irregular Regions

Description

Performs least-squares crossvalidation for the lattice-based non-parametric regression estimator.

Usage

crossvalNparReg(formLatticeOutput, Z, PointPattern, M = 0.5, max_steps = 200)

Arguments

formLatticeOutput	An object from formLattice or editLattice.
Z	Vector of response values to be smoothed.
PointPattern	A 2-column matrix or data frame of locations.
M	Maximum probability that the random walk moves.
max_steps	Maximum number of steps attempted.

Details

For a given k, deleted residuals are computed for each of the observations. The crossvalidation is based on minimization of the squares of the deleted residuals.

Value

A list consisting of

• SumSq Vector of crossvalidated sums of squares

• Number of steps that minimizes the crossvalidated SS.

Author(s)

Ronald P. Barry

References

Ronald P. Barry, Julie McIntyre. Estimating animal densities and home range in regions with irregular boundaries and holes: A lattice-based alternative to the kernel density estimator. Ecological Modelling 222 (2011) 1666-1672.

Julie McIntyre, Ronald P. Barry (2018) A Lattice-Based Smoother for Regions with Irregular Boundaries and Holes. Journal of Computational and Graphical Statistics. <doi:10.1080/10618600.2017.1375935>

Examples

data(nparExample)
attach(nparExample)
plot.new()
#  Simulate a response variable
index1 <- (grid2[,2]<0.8)|(grid2[,1]>0.6)
Z <- rep(NA,length(grid2[,1]))
n1 <- sum(index1)
n2 <- sum(!index1)
Z[index1] <- 3*grid2[index1,1] + 4 + rnorm(n1,0,sd=0.4)
Z[!index1] <- -2*grid2[!index1,1] + 4 + rnorm(n2,0,sd=0.4)
#
plot(polygon2,type="n")
polygon(polygon2)
points(grid2,pch=19,cex=0.5,xlim=c(-0.1,1))
text(grid2,labels=round(Z,1),pos=4,cex=0.5)
#
nodeFillingOutput <- nodeFilling(poly=polygon2, node_spacing=0.025)
plot(nodeFillingOutput)
formLatticeOutput <- formLattice(nodeFillingOutput)
plot(formLatticeOutput)
hold <- crossvalNparReg(formLatticeOutput,Z,
                       PointPattern=grid2,M=0.5,max_steps = 40)
NparRegOut <- createNparReg(formLatticeOutput,Z,PointPattern=grid2,k=hold$k)
plot(NparRegOut)

latticeDensity documentation built on April 18, 2021, 5:06 p.m.