[R-sig-Geo] ggwr and memory problems

[Roger Bivand]

On Mon, 21 Jan 2008, Luca Moiana wrote:

> Dear List,
>
> Here is my problem:
>
> I wanna run a ggwr on a 9000 records Spatial Points Data Frame using R 
> on a Windows Machine (Dual processor, 4 GB RAM).

Have you tuned Windows memory use as discussed in the R for Windows FAQ - 
section 2.9? The binaries are 32-bit, and need to be told how much memory 
to use when trying to carry out memory intensive work.

>
> When I try to calculate bandwidth using:
>
> Sdati14400test.sel
> <- ggwr.sel(E14400 ~ V211 + V213 + V240 + V313 + V321 + V322 + V331511 +
> LnMPI25l.max + B:A, family = poisson(link = log), data = Sdati14400test,
> coords=Sdati14400test.coords, adapt = FALSE, gweight = gwr.gauss, verbose =
> TRUE, longlat = FALSE)
>
> I get a memory allocation error saying that the software is not able to 
> allocate a 749 Mb memory.
>
> Any suggestion??

It isn't strictly necessary to use all the observations to find the 
bandwidth - take a couple of 5% samples and see if the results differ 
much.

>
> I can also switch and use the same machine with a 64bit Ubuntu SO.
>

You can try that, but consider dividing the fit.points up into chunks, and 
running several R processes when actually fitting the ggwr model. The data 
points stay the same, but fit subsets of the fit.points in separate 
processes.

ggwr() has not (yet) been adapted for using a cluster, but gwr() has and a 
snow socket cluster will run happily on Linux there, and since it is run 
within the function, it concatenates the results before returning. If this 
would be useful of ggwr(), consider taking a look at the code.

Roger

>
> THANK A LOT
>
>
>
> Luca Moiana
>
>
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-- 
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