>3. Cut the basin polygons using a geological polygon map and and calculate km2 or percentage of km2 for each lithological >unit found within each basin. After denormalizing these areas & lithologies (rows as samples and the columns km2 of each >lithology) one can then perform linear regression models on the chemical analysis.
at least for 3.: you may stay in the raster world? e.g. in a loop - v.to.rast your geological map - calculate your basin with the sample points (x,y coordinates) by r.water.outlet [3] - do r.stats [2] with the rasterized geological map and your basin to get the percent/km2 portion of geologic units per basin; you can export these statistics to a csv file - join back this csv file to your vector outlet point have a look at [4] where I've done this workflow mentioned above in an addon [1] https://trac.osgeo.org/grass/browser/grass-addons/grass7/vector/v.habitat.dem/v.habitat.dem.py [2] https://grass.osgeo.org/grass73/manuals/r.stats.html [3] https://grass.osgeo.org/grass73/manuals/r.water.outlet.html [4] https://trac.osgeo.org/grass/browser/grass-addons/grass7/vector/v.habitat.dem/v.habitat.dem.py#L411 ----- best regards Helmut -- View this message in context: http://osgeo-org.1560.x6.nabble.com/Non-Topological-Vector-Polygon-Layer-From-r-water-outlet-tp5292824p5292867.html Sent from the Grass - Users mailing list archive at Nabble.com. _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
