[postgis-users] st_clusterwithin on postgis 2
Paolo Importuni
imppao at gmail.com
Thu Sep 22 08:08:03 PDT 2016
Hi Birgit, thank you very much for your reply.
I'm going to test your code asap and let you know about it.
Regards,
Paolo
2016-09-22 9:47 GMT+02:00 Birgit Laggner <birgit.laggner at thuenen.de>:
> Hi Paolo,
>
> sorry, I did not really think it through, but now the changed and tested
> example:
>
> DO $$
> DECLARE distance numeric; t_schema varchar; input_table varchar;
> output_table varchar; r record; gid integer; geom geometry; c record; c_gid
> integer[]; c_geom geometry[]; i record;
> BEGIN
>
> distance := 200;
> t_schema := 'p_sam';
> input_table := 'cluster_test_input';
> output_table := 'cluster_test_output';
>
>
> CREATE TEMP TABLE clustered (gid integer) ON COMMIT DROP;
>
> EXECUTE 'SELECT gid, geom FROM '||quote_ident(t_schema)||'.'||quote_ident(input_table)
> INTO r;
>
> gid := r.gid;
> geom := r.geom;
>
> EXECUTE 'INSERT INTO clustered SELECT '||gid;
>
> LOOP
>
> EXECUTE 'SELECT array_agg(gid) as gid, array_agg(geom) as geom
> FROM '||quote_ident(t_schema)||'.'|
> |quote_ident(input_table)||'
> WHERE gid NOT IN (SELECT gid FROM clustered) AND
> ST_DWithin($1, geom, $2)'
> INTO c USING geom, distance;
>
> c_gid := c.gid;
> c_geom := c.geom || array[geom]::geometry[];
>
> EXECUTE 'INSERT INTO clustered SELECT unnest($1)' USING c_gid;
>
> geom := ST_ForceCollection(ST_Collect(c_geom));
>
> EXIT WHEN c IS NULL;
>
> END LOOP;
>
> EXECUTE 'INSERT INTO '||quote_ident(t_schema)||'.'||quote_ident(output_table)||'
> VALUES($1)' USING geom;
>
> LOOP
> BEGIN
> EXECUTE 'SELECT gid, geom FROM '||quote_ident(t_schema)||'.'|
> |quote_ident(input_table)||'
> WHERE gid NOT IN (SELECT gid FROM clustered)' INTO r;
>
> gid := r.gid;
> geom := r.geom;
>
> EXECUTE 'INSERT INTO clustered SELECT '||gid;
>
> LOOP
>
> EXECUTE 'SELECT array_agg(gid) as gid, array_agg(geom) as geom
> FROM '||quote_ident(t_schema)||'.'|
> |quote_ident(input_table)||'
> WHERE gid NOT IN (SELECT gid FROM clustered) AND
> ST_DWithin($1, geom, $2)'
> INTO c USING geom, distance;
>
> c_gid := c.gid;
> c_geom := c.geom || array[geom]::geometry[];
>
> EXECUTE 'INSERT INTO clustered SELECT unnest($1)' USING c_gid;
>
> geom := ST_ForceCollection(ST_Collect(c_geom));
>
> EXIT WHEN c IS NULL;
>
> END LOOP;
>
> EXECUTE 'INSERT INTO '||quote_ident(t_schema)||'.'|
> |quote_ident(output_table)||'
> VALUES ($1)' USING geom;
>
> EXCEPTION WHEN SQLSTATE '22004' THEN EXIT;
> END;
> END LOOP;
>
> END $$
>
>
> Regards,
>
> Birgit
>
> Am 21.09.2016 um 14:53 schrieb Birgit Laggner:
>
> Hi Paolo,
>
> here an example how it could work (mind that you have to replace the ??).
> You could also recode the DO block into a function if you would like that
> better.
>
> DO $$
> DECLARE distance numeric; t_schema varchar; input_table varchar;
> output_table varchar; r record; gid integer; geom geometry; c record; c_gid
> integer[]; c_geom geometry;
> BEGIN
>
> distance := ??;
> t_schema := '??';
> input_table := '??';
> output_table := '??';
>
>
> CREATE TEMP TABLE clustered (gid integer) ON COMMIT DROP;
>
> EXECUTE 'SELECT gid, geom FROM '||quote_ident(t_schema)||'.'||quote_ident(input_table)
> INTO r;
>
> gid := r.gid;
> geom := r.geom;
>
> EXECUTE 'INSERT INTO clustered SELECT '||gid;
>
> EXECUTE 'SELECT array_agg(gid) as gid, ST_ForceCollection(ST_Collect(ST_Collect(geom),$2))
> as geom FROM '||quote_ident(t_schema)||'.'||quote_ident(input_table)||'
> WHERE gid != $1 AND ST_DWithin($2, geom, $3)' INTO c USING gid, geom,
> distance;
>
> c_gid := c.gid;
> c_geom := c.geom;
>
> EXECUTE 'INSERT INTO '||quote_ident(t_schema)||'.'||quote_ident(output_table)||'
> VALUES($1)' USING c_geom;
>
> EXECUTE 'INSERT INTO clustered SELECT unnest($1)' USING c_gid;
>
> LOOP
> BEGIN
> EXECUTE 'SELECT gid, geom FROM '||quote_ident(t_schema)||'.'|
> |quote_ident(input_table)||'
> WHERE gid NOT IN (SELECT gid FROM clustered)' INTO r;
>
> gid := r.gid;
> geom := r.geom;
>
> EXECUTE 'INSERT INTO clustered SELECT '||gid;
>
> EXECUTE 'SELECT array_agg(gid) as gid, ST_ForceCollection(ST_Collect(ST_Collect(geom),$1))
> as geom
> FROM '||quote_ident(t_schema)||'.'||quote_ident(input_table)||'
> WHERE gid NOT IN (SELECT gid FROM clustered) AND ST_DWithin($1,
> geom, $2)'
> INTO c USING geom, distance;
>
> c_gid := c.gid;
> c_geom := c.geom;
>
> EXECUTE 'INSERT INTO '||quote_ident(t_schema)||'.'|
> |quote_ident(output_table)||'
> VALUES ($1)' USING c_geom;
>
> EXECUTE 'INSERT INTO clustered SELECT unnest($1)' USING c_gid;
>
> EXCEPTION WHEN SQLSTATE '22004' THEN EXIT;
> END;
> END LOOP;
>
> END $$
>
> Regards,
>
> Birgit
> Am 21.09.2016 um 07:47 schrieb Paolo Importuni:
>
> Hi all,
> I need to run a query on my postgres/postgis (9.3/2.0) that uses
> ST_CLUSTERWITHIN function. This function is available since postgis 2.2.0
> so I should do a soft upgrade on my ubuntu server. Since we have a kind of
> customer demo in a few days and have no much time left, I am not willing
> to change our setup right now, and I'd rather do it after that meeting.
> The question is: is there a way to aggregate geometries like
> ST_ClusterWIthin does? Anybody can provide any working examples?
>
> Thanks and regards
>
> Paolo I.
>
>
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