R: Compositional Ordinary Kriging

compOKriging {compositions} | R Documentation

## Compositional Ordinary Kriging

### Description

Geostatistical prediction for compositional data with missing values.

### Usage

    compOKriging(comp,X,Xnew,vg,err=FALSE)

### Arguments

`comp` | an acomp compositional dataset
`X` | A dataset of locations
`Xnew` | The locations, where a geostatistical prediction should be computed.
`vg` | A compositional variogram function.
`err` | boolean: If true kriging errors are computed additionally.

### Details

The function performes multivariate ordinary kriging of compositions based on transformes addapted to the missings in every case. The variogram is assumed to be a clr variogram.

### Value

A list of class `"logratioVariogram"`

`X` | The new locations as given by Xnew
`Z` | The predicted values as acomp compositions.
`err` | An ncol(Z)xDxD array with the clr kriging errors.

### Author(s)

K.Gerald v.d. Boogaart http://www.stat.boogaart.de

### References

Pawlowsky-Glahn, Vera and Olea, Ricardo A. (2004) Geostatistical Analysis of Compositional Data, Oxford University Press, Studies in Mathematical Geology

Tolosana (2008) ...

Tolosana, van den Boogaart, Pawlowsky-Glahn (2009) Estimating and modeling variograms of compositional data with occasional missing variables in R, StatGis09

### See Also

`vgram2lrvgram`, `CompLinModCoReg`, `vgmFit`

### Examples

    ## Not run:
    # Load data
    data(juraset)
    X <- with(juraset,cbind(X,Y))
    comp <- acomp(juraset,c("Cd","Cu","Pb","Co","Cr"))
    lrv <- logratioVariogram(comp,X,maxdist=1,nbins=10)
    plot(lrv)

    # Fit a variogram model
    vgModel <- CompLinModCoReg(~nugget()+sph(0.5)+R1*exp(0.7),comp)
    fit <- vgmFit2lrv(lrv,vgModel)
    fit
    plot(lrv,lrvg=vgram2lrvgram(fit$vg))

    # Define A grid
    x <- (0:30/30)*6
    y <- (0:30/30)*6
    Xnew <- cbind(rep(x,length(y)),rep(y,each=length(x)))

    # Kriging
    erg <- compOKriging(comp,X,Xnew,fit$vg,err=FALSE)
    par(mar=c(0,0,1,0))
    pairwisePlot(erg$Z,panel=function(a,b,xlab,ylab) {image(x,y,
                         structure(log(a/b),dim=c(length(x),length(y))),
                         main=paste("log(",xlab,"/",ylab,")",sep=""));points(X,pch=".")})

    # Check interpolation properties
    ergR <- compOKriging(comp,X,X,fit$vg,err=FALSE)
    pairwisePlot(ilr(comp),ilr(ergR$Z))
    ergR <- compOKriging(comp,X,X+1E-7,fit$vg,err=FALSE)
    pairwisePlot(ilr(comp),ilr(ergR$Z))
    ergR <- compOKriging(comp,X,X[rev(1:31),],fit$vg,err=FALSE)
    pairwisePlot(ilr(comp)[rev(1:31),],ilr(ergR$Z))

    ## End(Not run)

[Package compositions version 1.40-3 Index]