[postgis-devel] Geometry clustering functions

[Paragon Corporation]

I'd prefer just one function with a default distance argument of 0.
 
Thanks,
Regina

  _____  

From: postgis-devel-bounces at lists.osgeo.org
[mailto:postgis-devel-bounces at lists.osgeo.org] On Behalf Of Paul Ramsey
Sent: Thursday, January 15, 2015 5:23 PM
To: PostGIS Development Discussion
Subject: Re: [postgis-devel] Geometry clustering functions


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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