PostGIS
Description
An aggregate function that returns an array of GeometryCollections, where each collection is a cluster containing some input geometries. Clustering partitions the input geometries into sets in which each geometry is within the specified `distance` of at least one other geometry in the same cluster. Distances are Cartesian distances in the units of the SRID.
ST_ClusterWithin is equivalent to running
ST_ClusterDBSCAN with minpoints := 0.
Availability: 2.2.0
This
method supports Circular Strings and Curves.
Examples
WITH testdata AS
(SELECT unnest(ARRAY['LINESTRING (0 0, 1 1)'::geometry,
'LINESTRING (5 5, 4 4)'::geometry,
'LINESTRING (6 6, 7 7)'::geometry,
'LINESTRING (0 0, -1 -1)'::geometry,
'POLYGON ((0 0, 4 0, 4 4, 0 4, 0 0))'::geometry]) AS geom)
SELECT ST_AsText(unnest(ST_ClusterWithin(geom, 1.4))) FROM testdata;
--result
st_astext
---------
GEOMETRYCOLLECTION(LINESTRING(0 0,1 1),LINESTRING(5 5,4 4),LINESTRING(0 0,-1 -1),POLYGON((0 0,4 0,4 4,0 4,0 0)))
GEOMETRYCOLLECTION(LINESTRING(6 6,7 7))