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/*PGR-GNU*****************************************************************
File: separateTouching.sql
Copyright (c) 2025 pgRouting developers
Mail: project@pgrouting.org
Copyright (c) 2025 Celia Virginia Vergara Castillo
Mail: vicky at erosion.dev
------
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
********************************************************************PGR-GNU*/
--v3.8
CREATE FUNCTION pgr_separateTouching(
TEXT, -- edges SQL
tolerance FLOAT DEFAULT 0.01, -- tolerance
dryrun BOOLEAN DEFAULT false,
OUT seq INTEGER,
OUT id BIGINT,
OUT sub_id INTEGER,
OUT geom geometry)
RETURNS SETOF RECORD AS
$BODY$
DECLARE
edges_sql TEXT := $1;
the_query TEXT;
sqlhint TEXT;
has_geom BOOLEAN;
has_id BOOLEAN;
BEGIN
BEGIN
edges_sql := _pgr_checkQuery($1);
EXCEPTION WHEN OTHERS THEN
GET STACKED DIAGNOSTICS sqlhint = PG_EXCEPTION_HINT;
RAISE EXCEPTION '%', SQLERRM USING HINT = sqlhint, ERRCODE = SQLSTATE;
END;
has_id := _pgr_checkColumn(edges_sql, 'id', 'ANY-INTEGER', true, dryrun => $3);
has_geom := _pgr_checkColumn(edges_sql, 'geom', 'geometry', true, dryrun => $3);
the_query := format($$
WITH
edges_table AS (
%s
),
get_touching AS (
SELECT e1.id id1, e2.id id2, ST_Snap(e1.geom, e2.geom, %2$s) AS geom, e1.geom AS g1, e2.geom AS g2
FROM edges_table e1, edges_table e2
WHERE e1.id != e2.id AND ST_DWithin(e1.geom, e2.geom, %2$s) AND NOT(
ST_StartPoint(e1.geom) = ST_StartPoint(e2.geom) OR ST_StartPoint(e1.geom) = ST_EndPoint(e2.geom)
OR ST_EndPoint(e1.geom) = ST_StartPoint(e2.geom) OR ST_EndPoint(e1.geom) = ST_EndPoint(e2.geom))
),
touchings AS (
SELECT id1, g1, g2, st_intersection(geom, g2) AS point
FROM get_touching
WHERE NOT (geom = g1) OR
(ST_touches(g1, g2) AND NOT
(ST_Intersection(geom, g2) = ST_StartPoint(g1)
OR ST_Intersection(geom, g2) = ST_EndPoint(g1)))
),
blades AS (
SELECT id1, g1, ST_UnaryUnion(ST_Collect(point)) AS blade
FROM touchings
GROUP BY id1, g1
),
collection AS (
SELECT id1, (st_dump(st_split(st_snap(g1, blade, %2$s), blade))).*
FROM blades
)
SELECT row_number() over()::INTEGER AS seq, id1::BIGINT, path[1], geom
FROM collection;
$$,
edges_sql, tolerance);
IF dryrun THEN
RAISE NOTICE '%', the_query || ';';
ELSE
RETURN QUERY EXECUTE the_query;
END IF;
END;
$BODY$ LANGUAGE 'plpgsql' VOLATILE STRICT;
COMMENT ON FUNCTION pgr_separateTouching(TEXT, FLOAT, BOOLEAN)
IS 'pgr_separateTouching
- Parameters
- Edges SQL with columns: id, geom
- Optional parameters
- tolerance => 0.01
- dryrun => true
- DOCUMENTATION:
- ${PROJECT_DOC_LINK}/pgr_separateTouching.html
';
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