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

I did a similar thing for a geographic application where I wanted to ensure I could cache point sets easily. My geohashing code looks like this:

def compute_chunk(latitude, longitude)
  (floor_lon(longitude) * 0x1000) | floor_lat(latitude)
end

def floor_lon(longitude)
  ((longitude + 180) * 10).to_i
end

def floor_lat(latitude)
  ((latitude + 90) * 10).to_i
end

Everything got really easy from there. I had some code for grabbing all of the chunks from a given point to a given radius that would translate into a single memcache multiget (and some code to backfill that when it was missing).