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Two additional options, if you want to expand beyond QGIS: In Spatialite there are the functions ST_StartPoint() and ST_EndPoint(). (Same in PostGIS). So you could do a query such as: SELECT line_id, ST_StartPoint(geometry) AS StartPoint, ST_EndPoint(geometry) AS EndPoint FROM lines; THis returns just the geometry (POINTS), so if you want them in a separate point table, you might do something like: CREATE TABLE end_points (pkuid primary key autoincrement, line_id integer); SELECT AddGeometryColumn('end_points','geometry',<EPSG code of your CRS>, 'POINT,2); INSERT INTO end_points (line_id, geometry) SELECT line_id, ST_StartPoint(geometry) FROM lines; INSERT INTO end_points (line_id, geometry) SELECT line_id, ST_EndPoint(geometry) FROM lines; Alternately, if you need the coordinates of the endpoints: SELECT line_id, AsWKT(ST_StartPoint(geometry)), AsWKT(ST_EndPoint(geometry)) FROM lines; And in addition you can also go to GRASS and use the v.to.points module with the "use=node" in order to create a point vector of nodes only from a GRASS line vector. So there are several ways to choose... On 07/01/2015 06:01 PM, CONTI Tonino
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THANKS RICHARD. DO I HAVE TO SELECT THE MAXIMUM AND MINIMUM VALUE FOR EACH ELEMENT AND DELETE THE OTHERS. YOU KNOW IF THERE IS A FUNCTION SELECTING THE FIRST AND LAST POINT OF EACH ITEM? TANKS TONINOTonino Conti Comune di Jesi Sistema Informativo Territoriale Tel 0731538312 - fax 0731538513 [email protected] www.comune.jesi.an.it/sit ________________________________________ Da: Richard McDonnell [[email protected]] Inviato: martedì 30 giugno 2015 16.43 A: CONTI Tonino Cc: [email protected] Oggetto: Re: [Qgis-user] extracting the starting point and end point from a linear geometry Tonino, From the toolbar...Vector, Geometry Tools, Extract Nodes. This I think should help! Regards, Richard McDonnell OPW - Ag féachaint don am atá le teacht - Ag caomhnú ón am atá thart OPW - Looking to the future - Caring for the past ********************************************************************** Email Disclaimer: http://www.opw.ie/en/disclaimer/ ********************************************************************** _______________________________________________ Qgis-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-user This mail was received via Mail-SeCure System. |
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