Display listings that are within X miles.

stevebluck

Hi everyone,

I'm thinking about starting a new project. This website lists holiday break venues. The main function I want is to have the user input thier postcode and how many miles they want to travel.

Then have the listings only show the venues within that distance.

How do I go about this? Do I have to use a third party database to check the data and calculate the distance?

I heard that I may be able to use google maps API for this?

Heres an example of what I want to acheive:

Steve enters in "CO10 1GE
Steve enters in "Within 20 miles"

Show all listings with postcodes within 20 miles of CO10 1GE.

Thank you!

CoderDan

Well, I don't have the time to do the research for you, I'll say 'yes' - use an API to get this done, odds are good google offers it, and that'd be the first place I'd look.

If you decide to write it yourself, I can help you with that, but that really is a huge undertaking, I've written one before, you're looking at databases of zipcodes that have the latitude and longitude in them, then radius math based on this to find what it encompasses, that for areas larger than a few miles really should factor in curvature of the earth, and all in all ends you up with a huge amount of data that needs to be updated regularly.

(actually, to be honest it's not that huge of a task to write, only take a day or 2 for the core code, but keeping the data up to date is a pain)

Randy_Jackson

You may want to look into Generic Mapping Tools. That may be able to help you out.

stevebluck

Cheers guys,

I know where to purchase an up-2-date database with all the postal codes, long, lat.

I also have a script that calculates the distance between one postcode to another.

However I'm gonig to need help trying to figure out how to work out the distance from one postal code to all of them and then returning all the post codes within distance and then matching them with my database.

If anyone is interested, let me know - will pay.

CoderDan

Doesn't really sound too hard.
The script you have that calculates distance between post codes. you have the radius math in there, it's not real complex.
Just do a query where you box off the selection of lat and lon that'll encompass your circular area, then run the resulting matches through the proper math to filter off any that don't match (and assign each a distance from your center), and you're done.

sneakyimp

There are a ton of places that offer zip code coordinates (and time zone info and whether they observe daylight savings, etc.). E.g., http://www.zip-codes.com

For that, I'd try googling 'zip code longitude latitude' and you'll probably see tons of results.

As for calculating the distance between two points, you may find this post helpful:
http://www.phpbuilder.com/board/showthread.php?t=10272986&page=2