attributes to categories

Malcolm Williamson malcolm at
Wed Apr 28 18:01:49 EDT 1993

> 	I have some files in dig format which are simply maps with several
> polygons within a circle.  Each polygon has an attribute in a dig_att
> file under the same name as the dig map.  These attributes are integer codes
> for a vegetation mix.  I would like to rasterize these maps so that the
> attributes become the category value in the raster map.  Then I want to
> reclassify the categories based on values in a lookup table. 
> 	I thought that when running I would end up with a raster
> map with the categories taken from my attribute file, but the cat file
> looks like this:
> GRASS 4.0 > more 3c1981.0
> # 373 categories
> 0.00 0.00 0.00 0.00
> 0:no data
> 	Can anyone outline the steps I need to take to get a raster file
> with the correct category values.  I have no labels for the categories
> because the categories themselves are numerically important.
> 	Thanks,
> ________________________________________________________________
> Doug Hersh			Boston University Marine Program
> dhersh at		Marine Biological Laboratory
> (508)548-3705 ext. 516		Woods Hole, MA  02543

Unless I misunderstand your situation, the category VALUES of your raster map
should already agree with the attributes of the original vector map. The cats
file is a lookup table for when you have category LABELS. You can check this
situation by querying your raster map with d.what.rast, and then seeing if
the values agree with your original vector map.

You should be able to reclass this map in the manner that you desire. Write
back if I'm all wet, or simply misunderstand your problem. Good luck!

Malcolm D. Williamson - Technical Assistant      E-mail: malcolm at
Center for Advanced Spatial Technologies      Telephone: (501) 575-5736
Ozark Rm. 214                                       Fax: (501) 575-3846 
University of Arkansas              
Fayetteville, AR 72701

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