[STATSGRASS] R - GRASS and r.reclass

[Roger Bivand]

On Thu, 18 Dec 2003, Roger Bivand wrote:

> On Thu, 18 Dec 2003, Hamish wrote:
> 
> > > I've done some very simple scripts to execute repeated operations on
> > > 25 GRASS maps. The problem is to pass values of reclassification rules
> > > to r.reclass. I've tried:
> > 
> > [...]
> > 
> > > But this doesn't work. I think that this could be also with a bash
> > > script, but I don't know anything about bash.
> > 
> > 
> > It is actually pretty clean with Bash, try the attached.
> 
> Yes, this does it, and could be written to a file from within R too. My 
> guess is that writing to a pipe to the shell could do it too, I'll have a 
> look. It's difficult to include in the examples, because they now run 
> without GRASS in their own temporary location. I'll post again when I've 
> found a route from within R.

On reflection, there is no need to do this from R - even the example of 
looping over raster cell indices in the Computers & Geosciences paper 
doesn't have to be done in R. r.reclass is also a better solution than 
reclassing in R, because it just stores changes in the classes of the 
original raster, and is thus much more economic.

Roger

> 
> Best wishes,
> 
> Roger
> 
> > 
> > 
> > regards,
> > Hamish
> > 
> > 
> > 
> > #!/bin/bash
> > #  reclass script
> > 
> > i=1
> > while [ $i -le 25 ] ; do
> > 
> >     r.reclass input=imagen$i output=imarec$i << EOF
> >        253 = 192
> >        252 = 96
> >        251 = 48
> >        250 = 24
> >        249 = 12
> >        221 = 8
> >        193 = 7
> >        165 = 6
> >        133 = 4
> >        102 = 3
> >        70 = 2
> >        39 = 1
> >        * = NULL
> >        end
> > EOF
> > 
> >     i=`expr $i + 1`
> > done
> > 
> > 
> > 
> > 
> > # if you want the maps to be 01,02,03,..,09,10,11 add this line:
> > # MAP=`echo $i | awk '{printf "%02i", $1}'`
> > # echo $MAP
> > 
> > _______________________________________________
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> > statsgrass at grass.itc.it
> > http://grass.itc.it/mailman/listinfo/statsgrass
> > 
> 
> 

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand at nhh.no