Hi, as usual I have a problem with R functions!
I formulated a geostatistical model with geoR.
I decided to include some covariates in my model, and I estimated all the
parameters (linear model and covariance function parameters) by the likfit
function as follows:
mod1<-likfit(geodata, ini=varfitmodel, trend=~cov1 +cov2, lambda=0.5,
cov.model="matern",kappa=0.5)
Once I obtained my best model, I'd like to validate it using an external
dataset by using the function xvalid.
First of all, I transformed the external dataset in a geodata object, as
usual, named
"validation_data"
,where also covariates were included.
Then I tried the following syntax:
Validation<-xvalid(geodata, model=mod1,
locations.xvalid=validation_data$coords, data.xvalid= validation_data$data)
Bur R says:
Trend elements not found.
My question is: how can I specify the trend structure within the xvalid
function?
Thank a lot
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