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I have a table of approx 10,000 - 20,000 dynamic points across the globe stored as lon/lat points. I want to cluster any point within (roughly) 3km of any other point into one point (and return the averaged center point of each cluster if possible). Unlike some other solutions I have seen, I do not just want points within 3km of the central cluster point, it is fine to have a point within each cluster many kilometres away from the central cluster point as long as there is a chain of points within 3km of each other joining the points together into a single chain/cluster.

The only way I can think of doing this is looping over every point, finding any other points within 3km of that point, and then recursively each of those points etc until i find all in that perticular chain/cluster, and then repeat for all the remaining un-clustered points - this would result in millions of calculations. Is there an easier way of doing this? Preferably with MYSQL 5.6 geospatial abilities, but im open to any viable solution.

  • Finding an optimal solution - i.e. with the minimum n clusters - is I believe, NP hard. One approach to finding any single sub-optimal solution is to use a Delaunay TIN. That is also rather hard to do in spherical co-ordinates - is projection an option (sowing up the 'sides' afterward)? – AnserGIS May 20 '14 at 12:51
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This spatial sql example will do exactly as you ask. Ignore the fact that the question asks for linear groups, it works fine with non-linear groups as well.

Group by cluster example

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