[R] bug in readRAST6 function in package spgrass6

[Roger Bivand]

On Fri, 1 Aug 2008, Rainer M Krug wrote:

> Hi
>
> if I try to import a raster layer which consists only of NULL values
> from grass by using the  readRAST6, I get an error message:
>
>
>> readRAST6("HSericea_seedsDisperse_2007")
> ERROR: Invalid value for null (integers only)
> Error in readBinGrid(rtmpfl11, colname = vname[i], proj4string = p4,
> integer = to_int) :
>  no such file:
> /home/rkrug/Documents/Projects/AlienSpread/R/../grass/simulation/.tmp/ecolmod/HSericea_seedsDisperse_2007
>

Please use the statgrass list for questions like this.

Examination of readRAST6() shows that if the NODATA= argument is not 
given, it is set to one less than the minimum data value. You have no data 
at all, so the heuristic fails. Set NODATA= and it should work.

Not a bug, rasters can reasonably be assumed to have data. If you like, 
on the appropriate list document a small case for which the heuristic 
should be changed to assign an arbitrary NODATA= (outside the range of the 
data) using information from r.info or other GRASS commands

Roger

>
> Thanks
>
> Rainer
>
>
> --
> Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
> Biology, UCT), Dipl. Phys. (Germany)
>
> Centre of Excellence for Invasion Biology
> Faculty of Science
> Natural Sciences Building
> Private Bag X1
> University of Stellenbosch
> Matieland 7602
> South Africa
>

-- 
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