[postgis-users] how to convert GeometryCollection to multipolygon shape

[isl...@infomed.sld.cu]

Hi people i need help in converting a shape that have a
GeometryCollection data to a multipolygon shape, at least a routine or
a function that do that.

thanks

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[Rémi Cura]

Hey,

have a look at ST_CollectionExctract.
http://postgis.refractions.net/docs/ST_CollectionExtract.html

Cheers,
Rémi-C

[isl...@infomed.sld.cu]

"Rémi Cura" <remi...@gmail.com> escribió:

But what I want is to homogenize an entire layer, for example, a layer
containing both multipolygons and collections, bring all components of
this layer to multipolygons.

something like this is that i want.

[isl...@infomed.sld.cu]

isl...@infomed.sld.cu escribió:

> "Rémi Cura" <remi...@gmail.com> escribió:
>
> But what I want is to homogenize an entire layer, for example, a
> layer containing both multipolygons and collections, bring all
> components of this layer to multipolygons.
>
> something like this is that i want.
>
>> Hey,
>> have a look at ST_CollectionExctract.
>> http://postgis.refractions.net/docs/ST_CollectionExtract.html
>>
>> Cheers,
>> Rémi-C

How can i use it, please give an exmaple

[Rémi Cura]

SELECT ST_CollectionExtract(geom,3) AS geom

FROM your_table_with_mixed_geometry

It will not change polygon or multi polygon, but will extract it from geometry collection.

CHeers,
Rémi-C

[Hugues François]

Hello,

If you want also declare polygons as multipolygons ("bring all components of this layer to multipolygons"), you can use ST_Multi(ST_CollectionExtract(geom,3))

Hugues.


De : postgis-us...@lists.osgeo.org [mailto:postgis-us...@lists.osgeo.org] De la part de Rémi Cura
Envoyé : dimanche 27 avril 2014 16:18
À : J.Alejandro Martinez Linares
Cc : PostGIS Users Discussion
Objet : Re: [postgis-users] how to convert GeometryCollection tomultipolygon shape