R: Computes kriging weights

krweights {geoR} | R Documentation

## 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))

[Package geoR version 1.7-5.2 Index]