Error with krige.cv
Bertrand, Several causes can lead to a singular covariance matrix; the most common is that you have duplicate observations (i.e. two or more observations on the same location). Use zerodist to find out. -- Edzer
bertrand toupin wrote:
Hi everyone, another obstacle towards the achievement :)
I'm trying to do a kriging of my data on a regular grid. My data is organized like :
Donnees (the data matrix)
Period x(km) y(km) Stations z(m)
1 400 400 22.5 120
1 430 500 34.5 56
etc....
For each period, I have 2300 stations.
So for t=1, I do :
vario=variogram(Stations~1,loc=~x+y,Donnees[Donnees$Periode==t,],cutoff=150,width=10)
modele1=fit.variogram(vario,vgm(max(vario[,3]),"Nug"),fit.method=1)
Info$KO1nugget[t]= modele1$psill[1]
valid=krige.cv(Stations~1,~x+y,model=modele1,data=Donnees[Donnees$Periode==t,])
The last command, I got this error :
" [using ordinary kriging]
"chfactor.c", line 130: singular matrix in function LDLfactor()
Erreur dans predict.gstat(object, newdata = data[sel, ], ...) :
LDLfactor "
I tried a lot of things, but nothing worked. Any idea?
Thanks!
Philippe
N.B. sessionInfo() gives :
sessionInfo()
Version 2.3.1 (2006-06-01)
i386-pc-mingw32
attached base packages:
[1] "methods" "stats" "graphics" "grDevices" "utils" "datasets" "base"
other attached packages:
gstat rgdal sp
"0.9-31" "0.4-10" "0.8-20"
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