Re: Re: Zipcode Proximity scriptby paulbort (Hermit)
|on Mar 31, 2003 at 19:35 UTC||Need Help??|
The advantage this has over blokhead's method is that it will work correctly regardless of circle size, and eliminate more points, in exchange for four extra calculations (N, S, E, W bounds). (Ten degrees is a lot of land.)
You might also want to consider storing the points in a database so that a SQL Query on a couple of indexes can do most of the data elimination for you in one pass.
Also, if you multiply the Lat/Longs by 10,000, you can store and manipulate them as longs instead of singles. (This alone might be enough to solve your performance problem.)
Just a quick stab at some SQL for this: (It assumes you've already calculated the bounding box.)
(With luck an optimizer will index seek the first four conditions before crunching the last one.)
This is a neat problem, I wish I had time to bang out some sample code.
Spring: Forces, Coiled Again!