This could help: http://wiki.iosa.it/spatial_analysis:feature_count
2008/12/8 Alex Mandel <[EMAIL PROTECTED]>: > Jonathan Greenberg wrote: >> I was hoping for a "crash course" in performing a spatial join between a >> polygon and a point layer in GRASS. I want to know, for each polygon in >> vector A, how many points from vector B fall within it, and the average, >> min, max and stdev of several numeric fields of those points from vector >> B falling in a given polygon from vector A. I was trying to do this in >> Arc but (surprise surprise) it keeps crashing... >> >> --j >> > > I can think of several ways to do this, though I haven't tried to do any > of things I'm about to mention. > > The most elegant seems to be: > > 1.v.what.vect > http://grass.itc.it/grass63/manuals/html63_user/v.what.vect.html > Create a column in the point layer to hold the polgyon id then use this > command to populate it based on the polygon layer. Once you have that > you can sum, avg, min, max with sql on the point table and group by > polygon id which let's you link it back to the polygon layer as a 1:1. > > Other things to look at > v.patch > v.distance > v.overlay > > Note specifically for you and other UCDavis affiliates we have a copy of > the GRASS book in the library(currently checked out) and have access to > the springer digital version. > http://www.springerlink.com/content/j21632/ just log into the library > proxy/vpn first. > > Of course this could also be done in PostGIS and possibly Spatialite > SQLite(Testing that right now) with a single query. > > Alex > _______________________________________________ > grass-user mailing list > grass-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/grass-user > _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user