compositions (version 2.0-2)

lrvgram: vgram2lrvgram

Description

Transforms model functions for different types of compositional (logratio)(co)variograms.

Usage

cgram2vgram(cgram)
vgram2lrvgram(vgram)

Arguments

cgram

A (matrix valued) covariance function.

vgram

A (matrix valued) variogram functions.

Value

A function that takes the same parameters as the input function (through a … parameterlist), but provides the correponding variogram values (cgram2vgram) or logratio Variogram (vgram2lrvgram) values.

Details

The variogram is given by cgram(0)-cgram(h) and lrvgram(h)[,i,j]==vgram(h)[,i,i]+vgram(h)[,i,j]-2*vgram(h)[,i,j].

The logratio-variogram is the set of variograms of each of the pairwise logratios. It can be proven that it carries the same information as a usual multivariate variogram. The great advantage is that all the funcitions have a direct interpreation and can be estimated even with (MAR) missings in the dataset.

References

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

See Also

logratioVariogram, CompLinModCoReg, vgmFit

Examples

# NOT RUN {
data(juraset)
comp <- acomp(juraset,c("Cd","Cu","Pb","Co","Cr"))
vg <- CompLinModCoReg(~nugget()+sph(0.5)+R1*exp(0.7),comp)
vg(1:3)
vgram2lrvgram(vg)(1:3)
# }