Clustering Lat/Longs in a Database

Question

I\'m trying to see if anyone knows how to cluster some Lat/Long results, using a database, to reduce the number of results sent over the wire to the application.

The

Answer 1

If you're clustering on geographic location, and I can't imagine it being anything else :-), you could store the "cluster ID" in the database along with the lat/long co-ordinates.

What I mean by that is to divide the world map into (for example) a 100x100 matrix (10,000 clusters) and each co-ordinate gets assigned to one of those clusters.

Then, you can detect very close coordinates by selecting those in the same square and moderately close ones by selecting those in adjacent squares.

The size of your squares (and therefore the number of them) will be decided by how accurate you need the clustering to be. Obviously, if you only have a 2x2 matrix, you could get some clustering of co-ordinates that are a long way apart.

You will always have the edge cases such as two points close together but in different clusters (one northernmost in one cluster, the other southernmost in another) but you could adjust the cluster size OR post-process the results on the client side.