Hello I have a vector map with points representing latrines and each point has an attribute describing the place name. I ran v.edit to snap points with a threshold of 5m and v.info reports 7296 features for the cleaned map. I now wish to count the number of latrines in each place, so I ran: > echo "SELECT *,count(Area) FROM MT_San_clean GROUP BY Area" | db.select and get a total of 10537, so the results are bogus.
Running the following command I can see the reason for the bogus results: > v.category in=MT_San_clean opt=print 1331/566/571/691/1332/456/416/410/405/561/390 1294/1249/1265/1229/1225/1273/1233 v.edit has assigned multiple categories to points when they were snapped. To get a meaningful count of points by Area I can think of two solutions: 1) Use awk to filter out the first category for each feature from the output of v.category opt=print and feed this list of cats into db.select, however I'm not sure of the sql syntax for WHERE "cat=MyListOfCats". 2) Use awk to filter out all, but the first category for each feature from the output of v.category opt=print and feed this list of cats into v.category opt=del, however I'm not sure of the relationship between feature ids and cats, and v.category wants a list of ids. Can someone please suggest an easier way or give me a pointer to implement either of my ideas? As a teaser I can offer to update [1] with the details :-) Many thanks, Craig [1] http://grass.osgeo.org/wiki/Count_points_in_polygon _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
