[postgis-users] Re: Cluster Analysis

Eli Dylan Lorimer e.d.lorimer at sms.ed.ac.uk
Sat Jul 16 09:06:18 PDT 2005

Hi Paul,
I think I'll try and go your suggested PL/R route. Is it true that I  
can essentially send the results of a spatial query to R and invoke  
*any* R function available on said data? I'm going to look into this  
anyway and hopefully get it all to gel well with GeoTools such that I  
can continue to make my requests over WFS.

As to your question about clusters on the fly, I like your idea of  
having the static table that I update via trigger, but I really need  
to dynamically pass a few parameters which will change the resulting  
clusters. Hum, I'll put some more thought into this idea though as  
that would be so much faster to do.



Are you calculating clusters on the fly? Do you need to? How about
having a clusters table, that is hooked to your base data table with
a trigger? That will be just as up-to-date as your base data, and
only have to do the calculations once per data update.


PS. A distance threshold "cluster" will return lots of unexpected and
unwanted results, which is why more sophisticated tricks have been

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