> That is exactly what I want to do... but first I want to find a way to boil > down all trips to 12 or so distinct paths; without having to overlay every > trip. But since I only have points, not streets; i have no way to say path > #1 is different from path #2.
Write a function that returns an intersection id based on a point; this function would have to find the closest intersection to the input. You need a table with intersection point geoms and intersection ids. The function could be a big case statement to start. You might also be able to finesse this with "snap to grid" or by rounding (look in the docs -- I would read the section on geometric functions and see if any strike you as useful) Then use array_accum and group by on the path# to create lists of intersection sequences. Compare these however you feel like. If you use another projection (UTM etc) the units will be in meters and easier to interpret. There is still a lot of work, but does that make sense? _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
