[R-sig-Geo] readRAST6() in {spgrass6}

[Roger Bivand]

On Tue, 10 May 2011, Sam Prentice wrote:

> Hi,
>
>
>
> I'm running R 2.12.2 via Tinn-R on Windows Server 2008. I'm using R for
> cluster analysis for terrain classification and I'm getting the following
> error when parsing GRASS data into R:
>
>
>
>> x =
> readRAST6(c("param_elev3","param_crosC_1m","param_longC_1m","param_slope5","
> param_profC","param_miniC_1m","param_maxiC_1m"))
>
> D:/GRASSdata/Sedgwick2/PERMANENT/.tmp/param_elev3 has GDAL driver GTiff
>
> and has 6224 rows and 6242 columns
>

Is the difficulty perhaps associated with the size of these rasters? The 
total size of the object will be over 2GB, are you using 64-bit Windows? 
How much memory do you have (over 16GB?)? Have you considered exporting 
the data manually (or using execGRASS()) from GRASS and using the raster 
package to use the data without necessarily reading it all into R, which 
will try to hold everything in memory unless you choose not to do so?

Could you make the same classification on subsets of your data? If you set 
your GRASS region to say 1000 by 1000, the problem may be resolved, 
because the object size will be much smaller, about 50MB. Older versions 
of r.out.gdal in GRASS, used here for loose coupling, did not respect 
region settings - is your GRASS version current, and the output region as 
chosen?

Hope this helps,

Roger

>
>
> Error in deleteDataset(DS) :
>
>                GDAL Error 1: Deleting
> D:/GRASSdata/Sedgwick2/PERMANENT/.tmp/param_elev3 failed:
>
> Permission denied
>
>
>
> On the surface this looked like an issue with user privileges, since I do
> not have admin-level user privileges on this machine. However, this has been
> corrected - I now have permissions on the .tmp directory listed in the
> error, and I can create, append, and delete any file in that location, but
> the error is still occurring.
>
>
>
> Thoughts?
>
>
>
> Thanks,
>
> Sam
>
>
> 	[[alternative HTML version deleted]]
>
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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