[postgis-users] getting unexpected results on an ST_Intersectsquery

Sat Apr 5 14:04:45 PDT 2014

I don't see any picture but it seems to me some ft_cubo's polygons intersects more than one polygon from sigfre_cub_adm_munic. You have to find the good query to keep the good one.  You could use st_area(st_intersection()) to achieve that

UPDATE
 ft_cubo
SET
 gidmunic = mgid
FROM (
WITH a AS (
 	SELECT DISTINCT ft_cubo.gid AS cgig, sigfre_cub_adm_munic.gid AS mgid , ST_area(ST_intersection(ft_cubo.the_geom, sigfre_cub_adm_munic.the_geom) AS inter_area
	FROM sigfre_cub_adm_munic, ft_cubo
	WHERE ST_Intersects(ft_cubo.the_geom,sigfre_cub_adm_munic.the_geom)
),

inter_max AS (
	SELECT cgid, max(inter_area) AS max_inter
	FROM a
	GROUP BY cgid
	)
SELECT a.*
FROM a
JOIN inter_max ON a.cgid = inter_max.cgid AND max_inter = inter_area
) AS foo
WHERE gid = cgid

Hugues.

-----Message d'origine-----
De : islanis at infomed.sld.cu [mailto:islanis at infomed.sld.cu] 
Envoyé : samedi 5 avril 2014 22:50
À : PostGIS Users Discussion; Hugues François
Objet : Re: [postgis-users] getting unexpected results on an ST_Intersectsquery

"Hugues François" <hugues.francois at irstea.fr> escribió:

> Hello,
>
> It's difficult to give an answer since you don't tell us a lot about 
> unexpected results buy you could try something like (will not work if  
> a ft_cubo's polygon intersects different sigfre_cub_adm_munic
> polygons) :
>
> UPDATE
>   ft_cubo
> SET
>   gidmunic = mgid
> FROM (
> SELECT DISTINCT ft_cubo.gid AS cgig, sigfre_cub_adm_munic.gid AS mgid 
> FROM sigfre_cub_adm_munic, ft_cubo WHERE
> ST_Intersects(ft_cubo.the_geom,sigfre_cub_adm_munic.the_geom)
> ) AS foo
> WHERE gid = cgid

this neither work, is doing the same thing, look to the picture, there are 2 towns, one is divided in many pieces, but this town is still the same town and this towns id, is the same that the towns id of one piece picture town. i need to do this. please

>
> HTH
>
> If it's not give the expected results, you can work on the subselect 
> query to return the expected unique gid pairs.
>
> Hugues.
>
>
>
> -----Message d'origine-----
> De : postgis-users-bounces at lists.osgeo.org
> [mailto:postgis-users-bounces at lists.osgeo.org] De la part de 
> islanis at infomed.sld.cu Envoyé : samedi 5 avril 2014 21:28 À : 
> postgis-users at lists.osgeo.org Objet : [postgis-users] getting 
> unexpected results on an ST_Intersects query
>
> Hi folks, I'm having problems when I try to run a simple query to 
> update the gidmunic field of ft_cubo layer, and it assigns a value 
> that does not exists in said field, please, i need help , the two 
> layers are multipolygon type. what should I do?
>
>
> UPDATE
>   ft_cubo
> SET
>   gidmunic = sigfre_cub_adm_munic.gid
> FROM sigfre_cub_adm_munic
> WHERE
> ST_Intersects(ft_cubo.the_geom,sigfre_cub_adm_munic.the_geom);
>
>
>
> thanks in advance
>
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-----Message d'origine-----
De : islanis at infomed.sld.cu [mailto:islanis at infomed.sld.cu] 
Envoyé : samedi 5 avril 2014 22:50
À : PostGIS Users Discussion; Hugues François
Objet : Re: [postgis-users] getting unexpected results on an ST_Intersectsquery

"Hugues François" <hugues.francois at irstea.fr> escribió:

> Hello,
>
> It's difficult to give an answer since you don't tell us a lot about 
> unexpected results buy you could try something like (will not work if  
> a ft_cubo's polygon intersects different sigfre_cub_adm_munic
> polygons) :
>
> UPDATE
>   ft_cubo
> SET
>   gidmunic = mgid
> FROM (
> SELECT DISTINCT ft_cubo.gid AS cgig, sigfre_cub_adm_munic.gid AS mgid 
> FROM sigfre_cub_adm_munic, ft_cubo WHERE
> ST_Intersects(ft_cubo.the_geom,sigfre_cub_adm_munic.the_geom)
> ) AS foo
> WHERE gid = cgid

this neither work, is doing the same thing, look to the picture, there are 2 towns, one is divided in many pieces, but this town is still the same town and this towns id, is the same that the towns id of one piece picture town. i need to do this. please

>
> HTH
>
> If it's not give the expected results, you can work on the subselect 
> query to return the expected unique gid pairs.
>
> Hugues.
>
>
>
> -----Message d'origine-----
> De : postgis-users-bounces at lists.osgeo.org
> [mailto:postgis-users-bounces at lists.osgeo.org] De la part de 
> islanis at infomed.sld.cu Envoyé : samedi 5 avril 2014 21:28 À : 
> postgis-users at lists.osgeo.org Objet : [postgis-users] getting 
> unexpected results on an ST_Intersects query
>
> Hi folks, I'm having problems when I try to run a simple query to 
> update the gidmunic field of ft_cubo layer, and it assigns a value 
> that does not exists in said field, please, i need help , the two 
> layers are multipolygon type. what should I do?
>
>
> UPDATE
>   ft_cubo
> SET
>   gidmunic = sigfre_cub_adm_munic.gid
> FROM sigfre_cub_adm_munic
> WHERE
> ST_Intersects(ft_cubo.the_geom,sigfre_cub_adm_munic.the_geom);
>
>
>
> thanks in advance
>
> ----------------------------------------------------------------
> This message was sent using IMP, the Internet Messaging Program.
>
>
>
> --
>
> Este mensaje le ha llegado mediante el servicio de correo electronico 
> que ofrece Infomed para respaldar el cumplimiento de las misiones del 
> Sistema Nacional de Salud. La persona que envia este correo asume el 
> compromiso de usar el servicio a tales fines y cumplir con las 
> regulaciones establecidas
>
> Infomed: http://www.sld.cu/
>
> _______________________________________________
> postgis-users mailing list
> postgis-users at lists.osgeo.org
> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
> _______________________________________________
> postgis-users mailing list
> postgis-users at lists.osgeo.org
> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>

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Infomed: http://www.sld.cu/