krweights: Computes kriging weights

In geoR: Analysis of Geostatistical Data

Computes kriging weights

Description

Computes the weights assign for each data point in simple and ordinary krigring

Usage

krweights(coords, locations, krige)

Arguments

coords	matrix with data coordinates
locations	matrix with coordinates of the prediciton points
krige	kriging parameters. See krige.control in krige.conv

Value

A matrix of weights

Examples

## Figure 8.4 in Webster and Oliver (2001), see help(wo)
attach(wo)
par(mfrow=c(2,2))
plot(c(-10,130), c(-10,130), ty="n", asp=1)
points(rbind(coords, x1))
KC1 <- krige.control(cov.pars=c(0.382,90.53))
w1 <- krweights(wo$coords, loc=x1, krige=KC1)
text(coords[,1], 5+coords[,2], round(w1, dig=3))
##
plot(c(-10,130), c(-10,130), ty="n", asp=1)
points(rbind(coords, x1))
KC2 <- krige.control(cov.pars=c(0.282,90.53), nug=0.1)
w2 <- krweights(wo$coords, loc=x1, krige=KC2)
text(coords[,1], 5+coords[,2], round(w2, dig=3))
##
plot(c(-10,130), c(-10,130), ty="n", asp=1)
points(rbind(coords, x1))
KC3 <- krige.control(cov.pars=c(0.082,90.53), nug=0.3)
w3 <- krweights(wo$coords, loc=x1, krige=KC3)
text(coords[,1], 5+coords[,2], round(w3, dig=3))
##
plot(c(-10,130), c(-10,130), ty="n", asp=1)
points(rbind(coords, x1))
KC4 <- krige.control(cov.pars=c(0,90.53), nug=0.382, micro=0.382)
w4 <- krweights(wo$coords, loc=x1, krige=KC4)
text(coords[,1], 5+coords[,2], round(w4, dig=3))
##
## SK vs OK
##
plot(c(-10,130), c(-10,130), ty="n", asp=1)
points(rbind(coords, x1))
KC5 <- krige.control(cov.pars=c(0.382,50))
w5 <- krweights(wo$coords, loc=x1, krige=KC5)
KC6 <- krige.control(type="sk", beta=2, cov.pars=c(0.382,50))
w6 <- krweights(wo$coords, loc=x1, krige=KC6)
text(coords[,1],  5+coords[,2], round(w5, dig=3))
text(coords[,1], -5+coords[,2], round(w6, dig=3))
##
plot(c(-10,130), c(-10,130), ty="n", asp=1)
points(rbind(coords, x1))
KC7 <- krige.control(cov.pars=c(0.382,0))
w7 <- krweights(wo$coords, loc=x1, krige=KC7)
KC8 <- krige.control(type="sk", beta=2, cov.pars=c(0.382,0))
w8 <- krweights(wo$coords, loc=x1, krige=KC8)
text(coords[,1],  5+coords[,2], round(w7, dig=3))
text(coords[,1], -5+coords[,2], round(w8, dig=3))

geoR documentation built on May 29, 2024, 1:36 a.m.