Instead of a list of class breaks, the user can also chose a classification algorithm and a number of classes (nbclasses). See the v.class for more information on these different algorithms.
Important note: The module currently supports only area vector type. For displaying thematic choropleth vector maps of other types (points, lines) can be used d.vect.thematic2 available in AddOns via g.extension.
d.vect.thematic -l map=communes3 column=pop \ breaks=111393.250000,222785.500000,334177.750000 \ colors="255:0:0,0:255:0,0:0:255,0,0,0"
d.vect.thematic -l map=communes2 column=pop/area algorithm=std \ nbclasses=5 colors="0:0:255,50:100:255,255:100:50,255:0:0,156:0:0"
# first save legend instructions to a file d.vect.thematic -n map=communes2 column=pop/area algorithm=std \ nbclasses=5 colors="0:0:255,50:100:255,255:100:50,255:0:0,156:0:0" \ legendfile=legend_pop_dens # open a monitor d.mon wx0 # draw the map d.vect.thematic map=communes2 column=pop/area algorithm=std \ nbclasses=5 colors="0:0:255,50:100:255,255:100:50,255:0:0,156:0:0" # draw the legend d.graph input=legend_pop_dens
# first save legend instructions to a file d.vect.thematic -n map=geology column=SHAPE_area algorithm=int nclasses=6 \ colors=215:48:39,252:141:89,254:224:139,217:239:139,145:207:96,26:152:80 \ legendfile=geology.leg # open the graphical display d.mon wx0 # draw outline of polygons d.vect map=geology type=boundary # draw color fill d.vect.thematic map=geology column=SHAPE_area algorithm=int nclasses=6 \ colors="215:48:39,252:141:89,254:224:139,217:239:139,145:207:96,26:152:80" \ # draw legend d.graph input=geology.leg
Check also Python module from AddOns: d.vect.thematic2
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