[thelist] Zip Code mysql db

martin.p.burns at uk.pwcglobal.com martin.p.burns at uk.pwcglobal.com
Sun Apr 14 08:16:01 CDT 2002


Memo from Martin P Burns of PricewaterhouseCoopers

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Hi Russell (and others who've been thinking about 'nearest X' problems
lately).

Here's a question which may or may not be relevant -
<tip type="questions to ponder for Zip code applications" author
="martin at members.evolt.org">
How useful is the absolute distance in a 'nearest X' application?

Is as useful as (say) "Within 100 miles' drive" or "Within 2 hours' travel
by $mode_of_transport"?

Now both of those are significantly harder to evaluate than a simple
trigonometric calculation between ZIP code centroids (they need knowledge
of the road networks for a start), but for many applications, are far more
useful and yield far more accurate answers to the question "What's my
nearest X?"

Another thing to think about - how big is the average Zip code? (I don't
know btw). If the distances you're thinking of are quite small in
comparison (particularly if the shape of each Zip code diverges
significantly from a simple square), then the accuracy of your results may
suffer, and you'll lose credibility in the minds of your users.
</tip>
Cheers
Martin



I need to search for the nearest entity in range of 100?? miles.



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