[R-sig-Geo] Convergence problems with spgwr

[Roger Bivand]

On Mon, 30 Mar 2009, Adalberto Pineda wrote:

> Thank you for your replies but it's my understanding that (for an adaptive model) the percentage
> should be entered at the "adapt" argument (based on the spgwr package manual and Roger's reply
> to this posting: https://stat.ethz.ch/pipermail/r-sig-geo/2005-August/000535.html).
>
> Also, the gwr function won't run on my data if I try bandwith = percentage.
> This is the error I get:
> "Error in print.gwr(list(SDF = <S4 object of class "SpatialPointsDataFrame">,  :
>  subscript out of bounds"
>
> Could you confirm me on this?

Until you can make gwr.sel() work, this is irrelevant. Please rescale your 
model until such time that gwr.sel() does converge, then read the gwr() 
help page properly - that (and the code) is the confirmation. First get 
rid of the 1e14 CVS scores!

Roger

>
> -- Adalberto.
>
>
> Adalberto Pineda
> Data Analytics Specialist
> MDA Dataquick
> 9620 Towne Centre Dr.
> San Diego, CA. 92121.
>
>
>
> -----Original Message-----
> From: Roger Bivand [mailto:Roger.Bivand at nhh.no]
> Sent: Saturday, March 28, 2009 8:49 AM
> To: Corey Sparks
> Cc: Adalberto Pineda; r-sig-geo at stat.math.ethz.ch
> Subject: Re: [R-sig-Geo] Converge problems with spgwr
>
>
> On Sat, 28 Mar 2009, Corey Sparks wrote:
>
>>
>> The problems is that you are sending the bandwidth (percentage) to the wrong
>> argument of gwr
>>
>> try:
>> coords<-cbind(data$X_COORD, data$Y_COORD)
>> percentage<-gwr.sel(Y ~ X1 + X2, data = data, coords = coords, adapt=TRUE,
>> longlat=TRUE)
>> adaptive.model<-gwr(Y ~ X1 + X2, data = data, coords = coords, adapt=TRUE,
>> bandwidth=percentage, longlat=TRUE)
>>
>> that should do the trick
>
> In addition, the model does have a major scaling problem, as can be seen
> by the CVS scores. Consider re-scaling the variables in the model, and you
> may find that gwr.sel() has an easier time.
>
> Roger
>
>> Corey
>>
>> I'm trying to fit an adaptive GWR model using the spgwr package but ran into
>> some problems.
>> Specifically, what I'm trying to do is to plug the optimal percentage
>> generated by the gwr.sel function into the gwr function.
>> This is my model's layout:
>>
>> coords<-cbind(data$X_COORD, data$Y_COORD)
>> percentage<-gwr.sel(Y ~ X1 + X2, data = data, coords = coords, adapt=TRUE,
>> longlat=TRUE)
>> adaptive.model<-gwr(Y ~ X1 + X2, data = data, coords = coords,
>> adapt=percentage, longlat=TRUE)
>>
>> But the gwr.sel function won't pass a value to the gwr function.  It seems
>> that gwr.sel fails to converge.  It just stops without giving any error
>> messages.
>> This is the output I've got:
>>
>> Adaptive q: 0.381966 CV score: 4.635847e+14
>> Adaptive q: 0.618034 CV score: 4.969922e+14
>> Adaptive q: 0.236068 CV score: 4.256574e+14
>> Adaptive q: 0.1458980 CV score: 3.818798e+14
>> Adaptive q: 0.09016994 CV score: 3.386485e+14
>> Adaptive q: 0.05572809 CV score: 2.959508e+14
>> Adaptive q: 0.03444185 CV score: 2.516265e+14
>>
>> Are there any known issues with the gwr.sel function?
>>
>> Corey Sparks
>> Assistant Professor
>> Department of Demography and Organization Studies
>> College of Public Policy
>> One UTSA Circle
>> San Antonio, TX 78239
>> corey.sparks at utsa.edu
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo at stat.math.ethz.ch
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
>

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no