Hello again, I do not have parent line id. All I have is a starting point from where the direction should reference.
On Wed, Sep 14, 2016 at 9:09 AM Leknín Řepánek <godzilalal...@gmail.com> wrote: > On Wed, Sep 14, 2016 at 12:09:23PM +0000, Jonatan Malaver wrote: > > the reason being is that I do a network analysis by running the following > > function: > > WITH RECURSIVE flow(gid, geom) AS ( > > SELECT e.gid, e.geom FROM electric_line e, transformers t WHERE > ST_Distance > > (t.geom,ST_StartPoint(e.geom)) <= 0.01 AND t.gid=$1 > > UNION ALL > > SELECT n.gid, n.geom > > FROM electric_line n, flow f > > WHERE ST_Distance(ST_EndPoint(f.geom),ST_StartPoint(n.geom)) <= 0.01 > > ) > > The problem I have is that some of the lines direction are in reversed. > I'm > > trying to correct them with referenced to the first line. Otherwise, I > will end > > up changing hundreds of lines manually. > Manually? No. There are many of possible ways how do this by query. For > example if you have in every line id of "parent line" you can use > anonymous block of code by something like this. > DO $$ > DECLARE line record; > BEGIN > FOR line in SELECT lines from lines ORDER BY id LOOP > IF NOT ST_Equal(ST_startpoint(line.geom) , (SELECT > ST_EndPoint(geom) FROM lines WHERE id = line.parent_line_id)) > THEN > UPDATE lines SET geom = ST_Reverse(geom) WHERE id = > line.id; > > END LOOP; > > END > > $$; > > > > > > On Tue, Sep 13, 2016 at 11:12 AM James Keener <j...@jimkeener.com> wrote: > > > > Depends on what you mean by direction. If you want to grab the start > and > > end points (st_startpoint and st_endpoint) and check their x and y > (st_x > > and st_y) for some condition (both less at the end?) Then update the > record > > with the value of st_reverse. > > > > I guess my other question is why it matters. > > > > Jim > > > > On September 13, 2016 8:31:07 AM EDT, Jonatan Malaver < > > jon.mala...@shrewsburyma.gov> wrote: > > > > Hello, > > > > I'm trying to come up with a query that would check the > direction of > > a line. If the end point is not the start point of the next line > to > > update the line by reversing that line. Can anyone give me > pointers on > > how to do it? > > > > Thanks, > > Jon > > > > > > postgis-users mailing list > > postgis-users@lists.osgeo.org > > http://lists.osgeo.org/mailman/listinfo/postgis-users > > > > > > -- > > Sent from my Android device with K-9 Mail. Please excuse my brevity. > > > > -- > > > > Thanks, > > > > > > Jonatan Malaver > > > > Assistant Engineer of Electrical and Cable Operations > > > > Shrewsbury Electric & Cable Operations > > > > 100 Maple Avenue > > > > Shrewsbury, MA 01545 > > > > Office: (508) 841-8610 > > > > Fax: (508) 842-9267 > > > > jon.mala...@shrewsburyma.gov > > > > > _______________________________________________ > > postgis-users mailing list > > postgis-users@lists.osgeo.org > > http://lists.osgeo.org/mailman/listinfo/postgis-users > > _______________________________________________ > postgis-users mailing list > postgis-users@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/postgis-users
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