Are they all multilinestrings ? What gives : select distinct geometryType(geom) from l4_3
If it is only Linestrings, then you can update your table: update l4_3 set geom = st_geometryN(geom); (If you have constraint on the geoemtry's type, you should use an "alter table..." construct to change the geometry type) Nicolas On 16 May 2013 14:03, Hugues François <hugues.franc...@irstea.fr> wrote: > ** > Hello, > > You may try to work with a dump of your multi into single > (st_dump(geom)).geom > > Hugues. > > > > ------------------------------ > *From:* postgis-users-boun...@lists.osgeo.org [mailto: > postgis-users-boun...@lists.osgeo.org] *On Behalf Of *Jonatan Malaver > *Sent:* Thursday, May 16, 2013 2:01 PM > > *To:* PostGIS Users Discussion > *Subject:* Re: [postgis-users] flow analysis > > OK, so after some research I found out that ST_StartPoint() returns NULL > for multilinestring. Anyone know a work around?**** > > ** ** > > Thanks,**** > > ** ** > > Jonatan**** > > ** ** > > *From:* postgis-users-boun...@lists.osgeo.org [mailto: > postgis-users-boun...@lists.osgeo.org] *On Behalf Of *Jonatan Malaver > *Sent:* Thursday, May 16, 2013 7:46 AM > *To:* PostGIS Users Discussion > *Subject:* Re: [postgis-users] flow analysis**** > > ** ** > > Here’s my query**** > > WITH RECURSIVE flow(gid, geom) AS (**** > > SELECT gid, geom FROM l4_3 WHERE gid = 212**** > > UNION ALL**** > > SELECT n.gid, n.geom**** > > FROM l4_3 n, flow f**** > > WHERE ST_DWithin(ST_EndPoint(f.geom),ST_StartPoint(n.geom),0.01)**** > > )**** > > SELECT gid, ST_AsText(geom)**** > > FROM flow;**** > > ** ** > > Here’s the result**** > > 212;"MULTILINESTRING((589700.21 2926252.04,589698.873744219 > 2926256.62316697))"**** > > ** ** > > l4_3 is a multilinestring of and electrical circuit. I would like to see > what’s downstream the grid from a transformer, fuse, or upstream from a > house meter.**** > > ** ** > > Thanks,**** > > ** ** > > Jonatan **** > > ** ** > > *From:* postgis-users-boun...@lists.osgeo.org [ > mailto:postgis-users-boun...@lists.osgeo.org<postgis-users-boun...@lists.osgeo.org>] > *On Behalf Of *Nicolas Ribot > *Sent:* Wednesday, May 15, 2013 12:55 PM > *To:* PostGIS Users Discussion > *Subject:* Re: [postgis-users] flow analysis**** > > ** ** > > Hello,**** > > ** ** > > This precise example, no, but the "WITH RECURSIVE" construct yes.**** > > ** ** > > Could you post your query and the data model ?**** > > ** ** > > Nicolas**** > > ** ** > > On 15 May 2013 17:56, Jonatan Malaver <jon.mala...@shrewsburyma.gov> > wrote:**** > > Hello again, **** > > I tried the example, but it only returns the same line. Has anyone tried > that example?**** > > **** > > Thanks,**** > > **** > > Jonatan **** > > **** > > *From:* postgis-users-boun...@lists.osgeo.org [mailto: > postgis-users-boun...@lists.osgeo.org] *On Behalf Of *Nicolas Ribot > *Sent:* Tuesday, May 14, 2013 1:02 PM > *To:* PostGIS Users Discussion**** > > > *Subject:* Re: [postgis-users] flow analysis**** > > **** > > Hi,**** > > **** > > The WITH RECURSIVE construct allows to walk a graph:**** > > **** > > This link may help:**** > > http://blog.cleverelephant.ca/2010/07/network-walking-in-postgis.html**** > > **** > > Nicolas**** > > **** > > On 14 May 2013 18:40, Jonatan Malaver <jon.mala...@shrewsburyma.gov> > wrote:**** > > Hello, is it possible to do any flow analysis? For example, query > postgis for what down flow a certain point?**** > > **** > > Thanks,**** > > **** > > Jonatan Malaver**** > > **** > > > _______________________________________________ > postgis-users mailing list > postgis-users@lists.osgeo.org > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users**** > > **** > > > _______________________________________________ > postgis-users mailing list > postgis-users@lists.osgeo.org > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users**** > > ** ** > > _______________________________________________ > postgis-users mailing list > postgis-users@lists.osgeo.org > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > >
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