Calculating distance between zip codes in PHP

Question

I grabbed a database of the zip codes and their langitudes/latitudes, etc from this This page. It has got the following fields:

ZIP, LATITUDE, LONGITUDE, CITY, STATE, COUNTY, ZIP_CLASS

The data was in a text file but I inserted it into a MySQL table. My question now is, how can i utilise the fields above to calculate the distance between two zip codes that a user can enter on the website? Working code in PHP will be appreciated

Answer 1

It can be done with just maths...

function calc_distance($point1, $point2)
{
    $distance = (3958 * 3.1415926 * sqrt(
      ($point1['lat'] - $point2['lat'])
      * ($point1['lat'] - $point2['lat'])
      + cos($point1['lat'] / 57.29578)
      * cos($point2['lat'] / 57.29578)
      * ($point1['long'] - $point2['long'])
      * ($point1['long'] - $point2['long'])
     ) / 180);

    return $distance;
}

Answer 2

See the SO question Geospatial Coordinates and Distance in Kilometres for insight and links. The conversion between miles and kilometres is discussed; you can omit it to get the answer in miles. The discussion also includes URLs to external sources of information.

Answer 3

You can also try hitting a web service to calc the distance. Let someone else do the heavy lifting.

http://www.codebump.com/services/PlaceLookup.asmx

Answer 4

Check out the Haversine formula for calculating great circle distances between two points. Some more samples can be found here

Haversine formula:

• R = earth’s radius (mean radius = 6,371km)
• Δlat = lat2− lat1
• Δlong = long2− long1
• a = sin²(Δlat/2) + cos(lat1).cos(lat2).sin²(Δlong/2)
• c = 2.atan2(√a, √(1−a))
• d = R.c

(Note that angles need to be in radians to pass to trig functions).

Answer 5

Check out the Aviation Formulary (http://williams.best.vwh.net/avform.htm) for more formulas than you could ever need for calculating things like this.

Answer 6

This is mike's answer with some annotations for the magic numbers. It seemed to work fine for me for some test data:

function calc_distance($point1, $point2)
{
    $radius      = 3958;      // Earth's radius (miles)
    $pi          = 3.1415926;
    $deg_per_rad = 57.29578;  // Number of degrees/radian (for conversion)

    $distance = ($radius * $pi * sqrt(
                ($point1['lat'] - $point2['lat'])
                * ($point1['lat'] - $point2['lat'])
                + cos($point1['lat'] / $deg_per_rad)  // Convert these to
                * cos($point2['lat'] / $deg_per_rad)  // radians for cos()
                * ($point1['long'] - $point2['long'])
                * ($point1['long'] - $point2['long'])
        ) / 180);

    return $distance;  // Returned using the units used for $radius.
}

Answer 7

There is a great php class for handling this sort of thing, including distance between zip codes, written by micah carrick originally. I've put together a step by step for implementing it which might help. http://go.sparkfire.net/2009/09/search-by-location-miles-from-zipcode-in-php/

Answer 8

i have some problem on such topic.I got my answer. thanks everybody