[R-sig-Geo] memory problems with GWR tests

[Michal Gallay]

Dear R-Experts,

there is an error message regarding allocation of memory coming up after 
attempting to run GWR with hatmatrix=TRUE (there is no problem when this is 
set to FALSE).

I would like to test GWR outputs using e.g. LMZ.F2GWR.test(x)or 
BFC99.gwr.test(x).

> resid.Gauss <- gwr(regress.formula, data=resid, gweight=gwr.Gauss, 
> bandwidth=10, hatmatrix=TRUE))

Error: cannot allocate vector of size 505.4 Mb


Why it cannot allocate 505 MB if there is 2 GB RAM on my laptop?
Running R from WinXP command prompt:
Rgui --max-mem-size=1800Mb
The memory problem persists.

I read the instructions regarding the memory.limit(), Memory(), as well as 
the R help.I could decimate the number of points involved in GWR but that 
would be a test on a different scale, wouldn't it? The datasets comprise 8 
000 - 1 000 000 points. A Monte Carlo simultation would require too much 
time.

I would like to know if there would be any way around the memory problem to 
test a GWR object.

I much appreciate any advice.

Michal

PS: There is some other information about the session:

My seesion info:

 sessionInfo()
R version 2.6.2 (2008-02-08) 
i386-pc-mingw32 

locale: 
LC_COLLATE=Slovak_Slovakia.1250;LC_CTYPE=Slovak_Slovakia.1250;LC_MONETARY=Slovak_Slovakia.1250;LC_NUMERIC=C;LC_TIME=Slovak_Slovakia.1250

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages: [1] lattice_0.17-6 spgwr_0.5-1 maptools_0.6-5 
foreign_0.8-23 sp_0.9-23

loaded via a namespace (and not attached):
[1] grid_2.6.2 

> gc()
         used (Mb) gc trigger  (Mb)  max used  (Mb)
Ncells 269045  7.2     531268  14.2    531268  14.2
Vcells 413865  3.2   84325970 643.4 105241855 803.0
> memory.profile()
       NULL      symbol    pairlist     closure environment     promise 
          1        6876      143458        3669         825        5271 
   language     special     builtin        char     logical     integer 
      37538         151        1464       16489        4324        5293 
     double     complex   character         ...         any        list 
       2446           1       36010           0           0        3262 
 expression    bytecode externalptr     weakref         raw 
          1           0         665         177           1 
> 

-- 
Michal Gallay

Postgraduate Research Student
School of Geography, Archaeology and Palaeoecology
Queen's University
Belfast BT7 1NN
Northern Ireland

Tel: +44(0)2890 273929
Fax: +44(0)2890 973212
email: mgallay01 at qub.ac.uk
www: www.qub.ac.uk/geog