Proposal for two clustering functions: ---- {{{geometry[] ST_ClusterIntersecting(geometry geom)}}} Aggregate function returning an array of GeometryCollections representing the connected components of a set of geometries. - accepts Point/MultiPoint, LineString, MultiLineString, Polygon, MultiPolygon geometries of any type that can be converted into GEOS (I can't think of a situation where Point/MultiPoint would be useful, but that doesn't mean there isn't one...)[[br]] - return a geometry array (my current implementation returns a GeometryCollection, but the recursive semantics of ST_Dump then undo all of the hard work)[[br]] Example: if run on a table containing all of the LineStrings in the image below, would return an array with two MultiLineString geometries (red and blue) [[http://i.stack.imgur.com/WNlxX.png]] ---- {{{geometry[] ST_ClusterWithin(geometry geom, double precision distance)}}} Aggregate function returning an array of GeometryCollections?/MultiPoints?, where any component is reachable from any other component with jump of no more than the specified distance. - like ST_ClusterIntersecting, but uses a distance threshold rather than intersection when determining if two geometries should be included in the same component. Could have an implementation very similar to ST_ClusterIntersecting, or could be restricted to points and maybe have a more efficient implementation.[[br]] - differs from kmeans in that a distance is provided, not a number of clusters[[br]] Example: In the picture below, an array of five MultiPoints would be returned (color-coded). The threshold distance in this case was more than the orange line but less than the pink line. [[http://ibin.co/1oH1ApWCoW8L]]