Create single value from Latitude and Longitude pair in PHP - php

Question

I'm working on a Google Maps project within a PHP application. I need to find a way to store a latitude and longitude pair as a singular value. I'm using this to help store markers with identical coordinates.
Is there way I can encode the latitude/longitude pair into a single string? I would like something like:
$lat = 45.18392;
$long = 62.18293;
// Would return a single string like 893jfd8sj39k
$single_string = make_single_string($lat, $long);
function make_single_string($lat, $long)
{
// Do something here with $lat and $long
return $single_string;
}
The most important part of the function is that it must return the same string EVERY time.
Thanks for the help!

Answer 1

I think you are looking for this:
function make_single_string($lat, $long)
{
$single_string = md5( $lat.'-'.$long );
return $single_string;
}
result will be something like this:
04f59f6c007149079d0b5cc81ee0d25f

Answer 2

You can return a hash of both numbers:
function make_single_string($lat, $long)
{
return md5($lat.'-'.$long);
}

Answer 3

Cant you concatenate the string on the return? with .'s...
return $lat . "," . $long;

Answer 4

Is there a reason that you're not using an object for this?
$lat = 45.18392;
$long = 62.18293;
$pos = array(
'lat'=>$lat,
'long'=>$long
);
It's much more readable and as a bonus you don't have to parse it later (can be easily serialized as well).

Answer 5

If you want reversibility (and you probably do) then you need to come up with a standard input format. Assuming your latitude can go between +/-90, and your longitudes between +/-180, you could do something like:
Make sure the latitude and longitude have signs. If positive, prepend the + sign.
Zero-pad on the front to two digits (for latitude) and three digits (for longitude). 9.2 degrees of latitude would become +09.2.
Zero-pad on the end to however many significant digits you want (say, six). 9.2 degrees of latitude would then become +09.200000.
Convert +, -, and . to some kind of standard notation. Say, P for +, M for -, and d for .. For 9.2 degrees of latitude you'd get P09d200000.
Concatenate the latitude and longitude.
Then you get a string that's reversible and only has alphanumeric characters in it. You might not need something this fancy, though.

Answer 6

Why not just concat them?
$string = $lat . "-" . $long;
I mean if you really wanted to I supposed you could take the above and use md5 on it:
$string = md5($lat . "-" . $long);

Answer 7

What you're looking for really exists, and is not as simple as md5( $lat.'-'.$long );, as to be effective must be done before a process of generalization.
It´s called Geohash. In PHP there are different implementations. This is good, but Google offers several options.

Answer 8

Use a class or plain object.
class
class Coord {
public $lat;
public $long;
__construct($lat, $long) {
$this->lat = $lat;
$this->long = $long;
}
}
$coord = new Coord(45.18392, 62.18293);
echo $coord->lat;
echo $coord->long;
plain object
$coords = new stdClass();
$coords->lat = 45.18392;
$coords->long = 62.18293;
echo $coord->lat;
echo $coord->long;
If you needs to save these in a database, you could serialize the objects into a string, then unserialize as you pull them again from the database.
http://php.net/manual/en/function.serialize.php