Zip Code Distances

[ashleyy]

Hi. I've recently acquired a zip code database which lists all zip codes, cities, and their respective latitudes and longitudes.

I can calculate the distance between the zip codes using the latitude and longitude, but what I want to do is find only those zip code distances that are, say, within 20 miles of each other.

I'm getting stuck on how to query that. My zip code distance is in a separate php function. How would I go about just listing the stores that have a returned function value of 20 or less?

I hope I've been clear enough in what I'm trying to do 😉

All help is greatly appreciated!

[bubblenut]

Well the equasion you need is

<?php
$distance=sqrt(pow(abs($x1)-abs($x2),2)+pow(abs($y1)-abs($y2),2));
?>

so if you have the coords of one zip and want to find all all the other places in an array within 200 miles of this one you would do something like.

<?php
$x1; //the known x-coord
$y1; //the known y-coord
$results=array();
for($i=0;$i<count($zip_array);$i++) {
  if(sqrt(pow(abs($x1)-abs($zip_array[$i]['xcoord']),2+pow(abs($y1)-abs($zip_array[$i]['ycoord']),2))<200) {
    $results[]=$zip_array[$i];
  }
}
?>

HTH
Bubble