[R-sig-Geo] optimize idw power

[Jon Olav Skoien]

Dominik,

The brute force approach shown in the link from Tom has in the mean time 
been implemented in the intamap package. See the example for the 
function "estimateParameters".

Cheers,
Jon

On 13-Aug-13 1:54, Thomas Adams wrote:
> Dominik,
>
> Look here:
> http://r-sig-geo.2731867.n2.nabble.com/GSTAT-Optimize-power-value-for-IDW-td2765918.html
>
> Tom
>
>
> On Mon, Aug 12, 2013 at 5:17 PM, Dominik Schneider <
> Dominik.Schneider at colorado.edu> wrote:
>
>> Hi,
>> I'd like to optimize the IDW power, similar to what ArcGIS does. I found
>> this old thread
>> http://www.mail-archive.com/r-sig-geo@stat.math.ethz.ch/msg04011.html but
>> was hoping someone could help adapt the solution. I am using
>>
>>
>> idw(residuals(mdl.stepaic[[j]])~1,locations=swe.nozeros[swe.nozeros$mth==mth
>> & swe.nozeros$yr==yr,],newdata=swe.grid)
>>
>> where mdl.stepaic[[j]] is a list of 39 regression equations. swe.nozeros is
>> a spatialpointsdataframe of observations. swe.grid is a grid where I want
>> new values predicted. I currently run this idw command through a loop of j
>> with no problems but I'd like to optimize both within each equation
>> represented by j and for the whole data set (so across the 39 timesteps).
>>
>> Below is what I'm starting with but I don't really understand how to get it
>> working. I appreciate your help.
>>
>> f= function(idp,formula,locations,newdata,...) {
>>
>> sum(idw(formula,locations,newdata),set=list(debug=0,idp=idp),...)$residuals**2
>> }
>>
>> optimize(f,interval=seq(1.4,1.7,by=0.1),formula=residuals(mdl.stepaic[[j]])~1,locations=swe.nozeros[swe.nozeros$mth==mth
>> & swe.nozeros$yr==yr,],newdata=swe.grid)
>>
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>>
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>
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-- 
Jon Olav Skøien
Joint Research Centre - European Commission
Institute for Environment and Sustainability (IES)
Land Resource Management Unit

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jon.skoien at jrc.ec.europa.eu
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