[thelist] closest location tool

[David Siedband]

Consider a GIS based solution.  It shouldn't be hard to find point data 
for the center of zip codes, as build a table with your locations and 
their GPS datum.

Check out the PostGIS extension for PostrgeSQL
http://postgis.refractions.net/

You can use it to calculate distances between the zip codes and the 
locations.

I would create a index table with one entry for each zip code and the 
LocationID of the closest location.  Iterate through the zip codes and 
find the closest location for each one.  Then cache the results.  
Repeat this process when you add new locations.  You could make this 
process more efficient by breaking the zip codes and locations into sub 
groups so you're not comparing every zip code against every location.

You could do this on a development machine and put the index table 
online using the database of your choice: MySQL, etc.

--
David Siedband

Oceanic Sky New Media
http://oceanicsky.com



On Jun 3, 2004, at 10:10 AM, Joel D Canfield wrote:

> Is calculating airline miles based on zip code still the best 'find our
> closest location' concept for the US?