[postgis-users] Determining clusters of points

[Sébastien Lorion]

Hello,

I am trying to find an efficient way to find clusters of points as shown in
the attached image. The only clustering criteria is the distance between the
points. The dataset can be very large (millions of points) and point
distribution is mostly clustered with some sparse points in the gaps.

I searched the net and this mailing list and found two promising solution
paths:

- use a statistical tools such as R with a density function (
http://www.r-project.org)
- use a clustering algorithm like those explained here
http://www.med.nyu.edu/biostatistics/people/Ilana%20Belitskaya-Levy/Courses/MAS/Handouts/clustering.pdf
(agnes
seems the most promising for my purposes)

<http://www.med.nyu.edu/biostatistics/people/Ilana%20Belitskaya-Levy/Courses/MAS/Handouts/clustering.pdf>I
would like your advice to help me find which approach would be best suited
with PostGIS (maybe there is even something already made that I can use?).
Whatever solution I pick, it must be efficient and the workload must be able
to be distributed on a cluster of commodity hardware.

I am new to GIS and this mailing list, so please excuse me if I am not using
the right vocabulary.

Thank you very much!

Sébastien
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