Possible distance quirk.

Post #189,185

1/5/05 11:22:00 PM

Depending on the latitudes and longitudes of your zip codes, it might be possible for it to mis-sort the distances slightly.

For instance, say you have three zip code areas in a line, west to east, in somewhat decreasing size. You have a dealer near the east edge of the western-most (#1). You have another dealer in the middle of the eastern-most (#3). You have a customer closer to the western edge than the centre of the middle one (#2). Which is going to list closer? Well, it depends on where the latitude and longitude are. If they're in defined as the middle of each area, then the customer is probably going to be told #3 is closer when he is in fact quite a bit closer to #1.

Now, this probably wouldn't happen all that often: it depends on how many dealers you have! But listing the closest 5 would tend to alleviate that and many people would understand the problem enough to overlook it, anyway.

Wade.

Is it enough to love
Is it enough to breathe
Somebody rip my heart out
And leave me here to bleed

Is it enough to die
Somebody save my life
I'd rather be Anything but Ordinary
Please

-- "Anything but Ordinary" by Avril Lavigne.

Post #189,188

by broomberg

1/6/05 12:05:42 AM

Yep, thought of that

Here is the email I sent to my boss when he asked me to look into it:

Seems straight forward.

How many dealers?

What about the granularity?

This is based on the center of the zip.

Does this need to find multiple dealers in a single or a couple of zips,
which would possibly send a person to the wrong area?

Post #189,190

by Another Scott

1/6/05 12:24:33 AM

Consider natural barriers like rivers too...

If I were to use something like this in the DC area, I'd want to consider that there are only a few Potomac river crossings. Thus a Lat/Long bee-line distance may be quite short, but the actual distance may be much longer due to the necessity of going across a major bridge.

If you were looking for the nearest McDonalds, it wouldn't be an issue. If you were looking for the nearest IKEA, it would be.

There's probably not a simple way around this problem (unless you're tied into MapQuest or something similar), so giving several possible answers and letting the user choose is probably the most reasonable approach.

Cheers,
Scott.

Post #189,191

by broomberg

1/6/05 12:30:16 AM

As the bird flies

That is the directive. So rivers, etc, are OK

Post #189,255

by static

1/6/05 7:37:35 PM

You do something clever with the number of results.

If you figure out (say) 10, then stop displaying them once the distance gaps get suddenly a lot bigger. So if someone is real close to 2, moderately close to another 3 and quite far from the next, they see 5. But if someone is moderately close to only 4, they see 4. And if someone is quite a ways from 3 and quite a long way from the next, they see 3.

Wade.

Is it enough to love
Is it enough to breathe
Somebody rip my heart out
And leave me here to bleed

Is it enough to die
Somebody save my life
I'd rather be Anything but Ordinary
Please

-- "Anything but Ordinary" by Avril Lavigne.

Post #189,263

by broomberg

1/6/05 8:30:10 PM

Too confusing

I can imagine the tech support calls when people get a variable number of responses that do not seem to correlate to exact distances.

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