[postgis-devel] Geometry clustering functions

[Paul Ramsey]

Do we want to go the “Accum” naming route, or introduce a “cluster” work?

ST_ClusterWithinDistance

Also, since the intersecting cluster is just the withindistance with a tolerance of zero, would having just one function be good or bad?

P.

-- 
Paul Ramsey
http://cleverelephant.ca
http://postgis.net

On January 15, 2015 at 2:07:24 PM, Daniel Baston (dbaston at gmail.com) wrote:

Glad to hear there is some interest!  I posted some ideas to http://trac.osgeo.org/postgis/wiki/DevClusteringFunctions

Thanks,
Dan

On Thu, Jan 15, 2015 at 12:28 PM, Paul Ramsey <pramsey at cleverelephant.ca> wrote:
Daniel,
This is interesting stuff, could you post some example function signature and input/output pictures on the wiki so we can do a little design review. I thing it’s very exciting and am very positive about it.

P

-- 
Paul Ramsey
http://cleverelephant.ca
http://postgis.net

On January 15, 2015 at 4:14:44 AM, Daniel Baston (dbaston at gmail.com) wrote:

Hello,

I'm working on a couple of C-language functions to solve some clustering problems I frequently face in PostGIS.  I'm wondering if there may be any level of interest in including such functions in the project?  I would be happy to flesh these out to include the error-handling and unit-testing that would be required.

Function #1 takes a GeometryCollection and returns the same geometries, re-aggregated into groups of interconnected geometries (solving a question I posted about at http://gis.stackexchange.com/q/94203 )

(Internally this builds an STRtree using GEOS and uses a union-find structure to identify connected components....as an aside, I am wondering if there is some way to take advantage of a database spatial index that may already exist)

Function #2 (not written) would solve a related problem - we want to take a set of points and return a set of MultiPoints, where each point in a MultiPoint is within distance X of some other point in the MultiPoint.

Thanks,
Dan
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