GRASS questions

[Lars Schylberg]

  1. Are there any modifications of r.reclass which 
     allow reclassification of data sets which 
     contain negative data values?

I am doing that all the time.  Is there some limitation in the 
software here that I don't know about?  For me it seems to work
ok.

  2. Are there any modifications of r.mask which
     allow for its noninteractive use?

Most of the time I create masks with r.mapcalc.
E.g.:  echo "MASK = if ( ...... )" | r.mapcalc

  3. Are there any written guides to the creation 
     and use of scripts in GRASS?

Yes there are some pages in the programming manual.
Good examples are found by looking at the current scripts
that are in Grass and by reading GrassClippings.  That is
how I have learned.

  4. Can scripts for GRASS be run only from within
     GRASS, or can they be run from UNIX also?

Yes, if you are setting up the same global variables in the
shell scripts as Grass is doing.  That is $LOCATION, $GISBASE,
$GISDBASE and a couple of others. Type "printenv" and have a look.

Lars

Lars Schylberg                          Email: larss at fmi.kth.se  
Dept. of Geodesy and Photogrammetry 
Royal Institute of Technology (KTH)     Tel.   +46 8 790 86 33   
S-100 44  STOCKHOLM, SWEDEN             Fax.   +46 8 790 66 10