Hi,
Thanks again.
Well, I have water pipes and consumption areas. So, the described method
should be correct. Moreover, the intersection is a first draft, as it
has to be manually corrected afterwards: a pipe might belong to an area
which it does not intersect.
I was more thinking in terms of sql efficiency. But I tested, and it
seems fast enough regarding my db volume.
Best regards,
Denis
On 06/20/2012 05:34 PM, Stephen Woodbridge wrote:
On 6/20/2012 10:43 AM, Denis Rouzaud wrote:
Hi Stefen, Hi Fred,
Thank you both for your answer.
There was effectively an invalidity in a geometry.
Now my function is working great.
But still, do you think it is a good idea to use an "order by" and
"limit 1" to have the desired result?
Yes, I have done similar queries. As an alternative you could split
the lines into multiple segments and then assign attributes to them
based on the polygons they fall into.
Imagine the case of a polyline that travels from city A to city B and
5% of the polyline is in A and 15% of the polyline is in B and 80% of
the polyline is not in A or B but the rural arear between the cities.
In you case you would always report it as being in B and 85% of the
time that would be wrong. Chopping the linestring into the 3 pieces is
a lot more work but would give better results.
So the correct answer for you has more to do with what your data
represents and if your polygons are discrete or form a coverage, etc.
and how tolerant you are to reporting errors as described above.
-Steve
Thanks again,
Denis
On 06/20/2012 04:27 PM, Stephen Woodbridge wrote:
Try:
select count(*) from polygons where not isvalid(geometry);
if count > 0 then
select count(*) from polygons where not isvalid(geometry) and not
isvalid(st_buffer(geometry, 0.0));
you can do an update to fix these:
update polygons set geometry=st_buffer(geometry, 0.0) where not
isvalid(geometry);
-Steve W
On 6/20/2012 7:54 AM, Denis Rouzaud wrote:
Hi all,
I have a table of line and a table of polygons. For a given line, I
would like to get the polygon which has the biggest intersection with
the line.
I tried something like this:
CREATE OR REPLACE FUNCTION distribution.get_zone_id(geometry) RETURNS
integer AS '
DECLARE
inputgeom ALIAS FOR $1;
id_poly integer;
BEGIN
SELECT id INTO id_poly
FROM polygons
WHERE ST_Intersects(inputgeom,geometry) IS TRUE
ORDER BY ST_Length(ST_Intersection(inputgeom,geometry))
DESC
LIMIT 1;
RETURN id_poly;
END
' LANGUAGE 'plpgsql';
But I have the following error:
ERROR: Error performing intersection: TopologyException: side
location
conflict at 553524.92178241001 147945.03792368001
If anyone has any idea, tip or whatever, it is very welcome!
Greetings,
Denis
_______________________________________________
postgis-users mailing list
postgis-users@postgis.refractions.net
http://postgis.refractions.net/mailman/listinfo/postgis-users
_______________________________________________
postgis-users mailing list
postgis-users@postgis.refractions.net
http://postgis.refractions.net/mailman/listinfo/postgis-users
_______________________________________________
postgis-users mailing list
postgis-users@postgis.refractions.net
http://postgis.refractions.net/mailman/listinfo/postgis-users
_______________________________________________
postgis-users mailing list
postgis-users@postgis.refractions.net
http://postgis.refractions.net/mailman/listinfo/postgis-users
_______________________________________________
postgis-users mailing list
postgis-users@postgis.refractions.net
http://postgis.refractions.net/mailman/listinfo/postgis-users
