Ruby haversine - finds the distance between to long/lats. Can be used as a paramater for sort.

haversize.rb

  def haversine(x, y) 
    r = 6371 
    lat1 = x.latitude 
    lat2 = y.latitude 
    lon1 = x.longitude 
    lon2 = y.longitude 
 
    d_lat = (lat2 - lat1) * Math::PI / 180 
    d_lon = (lon2 - lon1) * Math::PI / 180 
 
    lat1 = lat1 * Math::PI / 180 
    lat2 = lat2 * Math::PI / 180 
 
    a = (Math.sin(d_lat / 2) * Math.sin(d_lat / 2)) + (Math.sin(d_lon / 2) 
    c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a)) 
    r * c 
  end