You need to map the distance of each item to the reference point first.
Then you sort the map and then you can tell which has the lowest (or highest if you reverse the search) distance:
$ref = array(49.648881, -103.575312);
$items = array(
'0' => array('item1','otheritem1details....','55.645645','-42.5323'),
'1' => array('item1','otheritem1details....','100.645645','-402.5323')
);
$distances = array_map(function($item) use($ref) {
$a = array_slice($item, -2);
return distance($a, $ref);
}, $items);
asort($distances);
echo 'Closest item is: ', var_dump($items[key($distances)]);
Output:
Closest item is: array(4) {
[0]=>
string(5) "item1"
[1]=>
string(21) "otheritem1details...."
[2]=>
string(9) "55.645645"
[3]=>
string(8) "-42.5323"
}
Take care you have the right order of lat and long.
The distance function (only the header slightly changed and units have been dropped):
function distance($a, $b)
{
list($lat1, $lon1) = $a;
list($lat2, $lon2) = $b;
$theta = $lon1 - $lon2;
$dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) + cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
$dist = acos($dist);
$dist = rad2deg($dist);
$miles = $dist * 60 * 1.1515;
return $miles;
}
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