[GRASS-dev] vector symbology

GRASS GIS GRASS GIS developer
1

Hi,

I'm a new user of GRASS and I struggle with some options that I've
learned with ArcGIS and are not easy to find or do not exist here.
How can I set the symbology to a vector map to display map by
attributes (different columns - one at a time) with the same colours
for the same class/value/category?
Example: I have a layer of soil map and want to display it by map unit
- so that the same units have the same colour and not just a random
selection of colours assigned automaticaly for polygons.
Or other time same map displayed by soil type (other column within
attribute table) - broader selection - several map units fall within
the same type - particular types displayed with different colours -
prefferebly colours set manually.

Thanks for your help

Regards

Agata

2

Agata

In GRASS - d.vect.thematic.

But note that QGIS has more powerfull thematic mapping, and you can
open GRASS vector maps in QGIS, if you have a GDAL-GRASS plugin
installed. What OS are you using?

Maciek

3

Agata Gie³dowska wrote:

I'm a new user of GRASS and I struggle with some options that I've
learned with ArcGIS and are not easy to find or do not exist here.
How can I set the symbology to a vector map to display map by
attributes (different columns - one at a time) with the same colours
for the same class/value/category?
Example: I have a layer of soil map and want to display it by map unit
- so that the same units have the same colour and not just a random
selection of colours assigned automaticaly for polygons.
Or other time same map displayed by soil type (other column within
attribute table) - broader selection - several map units fall within
the same type - particular types displayed with different colours -
prefferebly colours set manually.

from the command line (but similar in gis.m), do it in multiple passes:
(spearfish dataset example)

d.vect soils type=area where="label ~ 'Va'" fcol=red
d.vect soils type=area where="label ~ 'Ca'" fcol=blue
d.vect soils type=area where="label ~ 'Ma'" fcol=green

d.vect archsites where="cat > 15" col=yellow

Instead of SQL database query with "where=", you can use cats=.

d.vect archsites cat=15-999 col=green

if you want to define a color to be used every time to fill a polygon,
create a new attribute column (usually called "GRASSRGB") with
RRR:GGG:BBB values (0-255), then "d.vect -a rgb_column=GRASSRGB".

and as Maciek mentioned, d.vect.thematic will do this automatically.

Hamish