ks (version 1.15.3)

kde.truncate: Truncated kernel density derivative estimate

Description

Truncated kernel density derivative estimate for 2-dimensional data.

Usage

kde.truncate(fhat, boundary) 
kdde.truncate(fhat, boundary)

Value

A truncated kernel density (derivative) estimate inherits the same object class as the input estimate.

Arguments

fhat

object of class kde or kdde

boundary

two column matrix delimiting the boundary for truncation

Details

A simple truncation is performed on the kernel estimator. All the points in the estimation grid which are outside of the regions delimited by boundary are set to 0, and their probability mass is distributed proportionally to the remaining density (derivative) values.

See Also

kde, kdde

Examples

data(worldbank)
wb <- as.matrix(na.omit(worldbank[,c("internet", "ag.value")]))
fhat <- kde(x=wb)
rectb <- cbind(x=c(0,100,100,0,0), y=c(0,0,100,100,0))
fhat.b <- kde.truncate(fhat, boundary=rectb)
plot(fhat, col=1, xlim=c(0,100), ylim=c(0,100))
plot(fhat.b, add=TRUE, col=4)
rect(0,0,100,100, lty=2)

library(oz)
data(grevillea)
wa.coast <- ozRegion(section=1)
wa.polygon <- cbind(wa.coast$lines[[1]]$x, wa.coast$lines[[1]]$y)
fhat1 <- kdde(x=grevillea, deriv.order=1)
fhat1 <- kdde.truncate(fhat1, wa.polygon)
oz(section=1, xlim=c(113,122), ylim=c(-36,-29))
plot(fhat1, add=TRUE, display="filled.contour")