[R-sig-Geo] How to do cross validation for universal krigingin Gstat

[Edzer Pebesma]

Kai Zhang wrote:
> Hi Edzer,
>
> Thanks for your quick reply. The primary variable of my interest is temperature.  I tried to use krige.cv before, but it did not work. The problem arises because the temperature and impervious surface are from two files. For universal kriging, the krige function has a parameter called "newdata" which handles the second data file. However, the krige.cv does not include a "newdata" parameter according to the help document. There is a error when I specified two datasources when I was running krige.cv in specifying a newdata source:  
>   
krige only works when the secondary variable (ELE) is present both in 
the data and in the newdata argument. krige.cv only uses the data 
argument, where ELE is present.
>   
>> dtw.vgm <- variogram(Temp~ Ele, TMP)
>> dtw.fit <- fit.variogram(dtw.vgm, model = vgm(1.45, "Exp", 9502,0))
>> uk.kriged.am <- krige.cv(Temp~Ele,data=TMP,newdata=IMP,model=dtw.fit)
>>     
> Error in function (classes, fdef, mtable)  : 
>   unable to find an inherited method for function "krige.cv", for signature "formula", "missing"
>   

> I tried to delete parameters names such as 'data' and 'newdata' according to your response to a related problem before in the R-sig-Geo archives. However, it still did not work.
>   
The krige.cv documentation does not mention a newdata argument. Pls try:

uk.kriged.am <- krige.cv(Temp~Ele, TMP, dtw.fit)

> Thanks,
> Kai Zhang
>
>
>
> ======= 2010-02-21 11:51:45 You wrote =======
>
>   
>> Kai,
>>
>> krige.cv(Temp~Ele, data, model)
>>
>> should do the job, assuming that your primary variable of interest is
>> temperature.
>> --
>> Edzer
>>
>>
>> Kai Zhang wrote:
>>     
>>> Dear all,
>>>
>>> I am attempting several Kriging methods to interpolate temperature in a area. It works well for me to use krige.cv to conduct cross validation for ordinary kriging and gstat.cv for co-kriging. However, I am confused on how to conduct cv for universal kriging. The temperature data is from the data file 1 and the secondary variable with more intense sampling is from another file. Krige.cv does not provide a parameter on 'newdata'. When I was trying gstat.cv, the variogram function automatically fits cross-variogram after I incorporate both temperature and the secondary information into a gstat object. Any suggestions are welcome.
>>>
>>> g <- gstat(NULL,id="Temp", formula=Temp~1, data=TMP)
>>> g <- gstat(g,id="Ele", formula=Ele~1, data=ELE)
>>> g <- gstat(g, id = "Temp", model = vgm(1, "Exp", 44559, 1))
>>> x <- variogram(g)
>>>
>>> Many thanks,
>>> Kai Zhang
>>>
>>>
>>>
>>> __________________________________________________
>>> 赶快注册雅虎超大容量免费邮箱?
>>>
>>> _______________________________________________
>>> R-sig-Geo mailing list
>>> R-sig-Geo at stat.math.ethz.ch
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>   
>>>       
>> -- 
>> Edzer Pebesma
>> Institute for Geoinformatics (ifgi), University of Münster 
>> Weseler Stra?e 253, 48151 Münster, Germany. Phone: +49 251 
>> 8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de 
>> http://www.52north.org/geostatistics      e.pebesma at wwu.de
>>
>>     
>
>
> 嗃i��'櫒ド╤∈&

-- 
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster 
Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251 
8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de 
http://www.52north.org/geostatistics      e.pebesma at wwu.de