[GRASS-stats] readRAST6() issue with NODATA

[Markus Neteler]

Dear Roger,

On Sat, Jun 12, 2010 at 6:51 AM, Roger Bivand <Roger.Bivand at nhh.no> wrote:
> On Sat, 12 Jun 2010, Markus Neteler wrote:
>
>> Dear Roger,
>>
>> hope all is well.
>>
>> I came across an issue with readRAST6():
>>
>>> library(spgrass6)
>>
>> Loading required package: sp
>> Loading required package: rgdal
>> Geospatial Data Abstraction Library extensions to R successfully loaded
>> Loaded GDAL runtime: GDAL 1.5.2, released 2008/05/29
>> Path to GDAL shared files: /home/neteler/binaries/share/gdal
>> Loaded PROJ.4 runtime: Rel. 4.6.1, 21 August 2008
>> Path to PROJ.4 shared files: (autodetected)
>> Loading required package: XML
>> GRASS GIS interface loaded with GRASS version: 6.4.0svn
>> and location: patUTM32
>>>
>>> mydata_raw <-readRAST6(c("thresh_annual_over_11_celsius_2001_2008_avg", "italy_dem20_PHD_zone"), cat=c(FALSE, FALSE))
>>
>>
>> /home/neteler/grassdata/patUTM32/zanzara_satellite/.tmp/fep/thresh_annual_over_11_celsius_2001_2008_avg
>> has GDAL driver GTiff
>> and has 601 rows and 1011 columns
>> WARNING: The given nodata value is present in rasterband
>>        <italy_dem20_PHD_zone> and would lead to data loss. Please specify
>>        a different nodata value with the nodata parameter.
>> ERROR: Raster export aborted.
>>
>> Debugging r.out.gdal, I found that the value 10 was used.
>>
>>
>> GRASS 6.4.0svn (patUTM32): > r.info -r italy_dem20_PHD_zone
>> min=0
>> max=3890
>> GRASS 6.4.0svn (patUTM32): > r.info -t italy_dem20_PHD_zone
>> datatype=CELL
>>
>> I hacked in -99999 as NODATA value in the r.out.gdal calls
>> (spgrass6/R/bin_link.R).
>>
>> I have no idea why 10 was used but from GRASS 6.4 onwards the r.out.gdal
>> module has an intelligent NODATA selection thanks to Markus Metz. I can
>> imagine what you don't want to clutter the code with conditions, but here
>> it
>> would be great to let the NODATA selection job to r.out.gdal rather than
>> using the current r.info tricks.
>
> Dear Markus,
>
> The tricks were there for the time when r.out.gdal didn't find its own
> value, and for the null parameter for r.out.bin. I've moved them down to the
> r.out.bin branch only, and modified the execGRASS() call to r.out.gdal to
> omit the nodata= argument by default when NODATA=NULL.
>
> Committed to sourceforge CVS, project r-spatial, module spgrass6. Could you
> check this and let me know if the problem is resolved?

Sorry for the delay, I was away.

I have updated from CVS and run

mydata_raw <-readRAST6(c("thresh_annual_over_11_celsius_2001_2008_avg",
"italy_dem20_PHD_zone"), cat=c(FALSE, FALSE))
/home/neteler/grassdata/patUTM32/zanzara_satellite/.tmp/fep/thresh_annual_over_11_celsius_2001_2008_avg
has GDAL driver GTiff
and has 601 rows and 1011 columns
/home/neteler/grassdata/patUTM32/zanzara_satellite/.tmp/fep/italy_dem20_PHD_zone
has GDAL driver GTiff
and has 601 rows and 1011 columns

No more errors, thanks!

Best wishes,
Markus

-- 
http://gis.ambiente.fmach.it/