[postgis-users] Count the roads that do not intersect with any other roads in the shpefile.

[Nicklas Avén]

Hallo Nicholas

I assume you mean that you hae your data in a postgis table not in
shapefile.

to find all roads that doesn't intersect any other road you find all
roads that do intersect and than catch the ones didn't find any
intersecton.

something like

SELECT a.gid, a.the_geom FROM mytable a LEFT JOIN mytable b on
ST_Intersects(a.the_geom, b.the_geom) WHERE a.gid != b.gid and b.gid IS
NULL;

Because of the left join you will get the records in table a that has no
intersection with any other road. And those cases can be detected
because then there will be only null in id field from table b.


HTH

Nicklas


On Mon, 2011-01-10 at 15:11 +0530, Nicholas I wrote:
> Hi,
> 
>  I am trying to find the roads, where the roads does not intersect
> with any other roads in the shapefile.
> Can some one help me.
> 
> thank you
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users