[postgis-users] get the biggest intersection

[Denis Rouzaud]

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?

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
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>
>
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