Use ST_MakeLine http://www.bostongis.com/postgis_makeline.snippet
If you are using PostgreSQL 9.0 its even easier since you can use the new Ordered aggregates feature and not need the subselect So PostgreSQL 9.0 implementation would look like SELECT Event_ID, ST_MakeLine(the_point ORDER BY time) as the_route FROM vehicle_tracking_data GROUP BY Event_ID; Leo and Regina http://www.postgis.us -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of dicky1980 Sent: Tuesday, October 12, 2010 5:15 AM To: [email protected] Subject: [postgis-users] Makeline help Hi, I need a bit of advice with the st_makeline function. We have some vehicle tracking data showing gritting activity. What we want to do is join up the points to create lines showing a travel path of what has been gritted. We can do a basic version of this but what we'd like is a seperate line for each group of events For eaxmple we have EVENT_ID Time 1 12.00 1 12:01 1 12:02 etc 1 1 2 2 2 2 1 1 What we'd like to be able to do is have it draw one line for the first event id group of 1s, then stop, draw a line for 2's, stop that line then start a new line for the next group of ones. What we have a present either jopins them all as one line, or if we just pull out aal the ones it will draw a line from the last 1 before the the two then join it to the next instance of one giving a untrue picture -- View this message in context: http://old.nabble.com/Makeline-help-tp29941457p29941457.html Sent from the PostGIS - User mailing list archive at Nabble.com. _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
