Area size of polygons with same value (building id) in GRASS GIS

Question

Is there a way to calculate the area size of multiple polygons having the same value (in this case building number) like group stats in QGIS?

Answer 1

The way to do this in GRASS uses a reclass of the vector layer, then when you update the database of this reclass vector with i.e. area, the total of the reclassed features will be calculated. See: v.reclass man page

If you have a buildings polygon with a integer or text field building_num, then:

v.reclass input=buildings output=buildings_by_num column=building_num
v.db.addtable map=buildings_by_num column="ttl_area DOUBLE"
v.to.db buildings_by_num option=area unit=meters column=ttl_area
v.db.select buildings_by_num  # should show one total value for each building num