Hello,
I have looked over a lot of documentation but am still having trouble with this task. I hope somebody on the list can point me in the right direction! I have a table of land parcels as polygon features in a postGIS database. I have another table of regions in the same postGIS database. There are between 20 and 50 parcels to a region. I can access the data without a problem (thanks to some helpful people!) I want to create several maps that aggregate/summarize the parcel data and display them as pie-charts and histograms at the centroid of each region. For example: 1. HISTOGRAM of the size of all parcels in the region. The data for this is stored in a single field for each parcel. I just need to understand how to identify the field, send it to the histogram, and display it at the centroid of the region layer. 2. PIE-CHART where each slice represents the total area owned by a particular class of owner. This is more complicated. EACH parcel has an area column for each of 7 classes of owners. So, I believe I need to keep separate tallies and send them all to a pie-chart function--but I am not sure how... Finally, is the best way to actually KEEP all this data to add new columns to the region table with SQL? thank you in advance, -david _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user