Compare two multidimensional arrays & Get difference & unique values in two different arrays PHP

Question

I have two multidimensional arrays with me..

$a1= Array
(
    [0] => Array
        (
            [sight_id] => 13
            [location] => Jodhpur, Rajasthan, India

        )

    [1] => Array
        (
            [sight_id] => 14
            [location] => Jodhpur Jn, Jodhpur, Rajasthan, India
                  )

    [2] => Array
        (
            [sight_id] => 15
            [location] => D-Kirtinagar, Jodhpur, Rajasthan, India

        )

   );


$a1= Array
(
    [0] => Array
        (
            [sight_id] => 13
            [location] => Jodhpur, Rajasthan, India

        )

    [1] => Array
        (
            [sight_id] => 14
            [location] => Jodhpur Jn, Jodhpur, Rajasthan, India
                  )

       [2] => Array
        (
            [sight_id] => 16
            [location] => Jaisalmer, Rajasthan, India

        )

    [3] => Array
        (
            [sight_id] => 17
            [location] => Fort Road, Amar Sagar Pol, Jaisalmer, Rajasthan, India

        ));

I want to split above given arrays into three different arrays..

$intersect_array=Array
(
    [0] => Array
        (
            [sight_id] => 13
            [location] => Jodhpur, Rajasthan, India

        )

    [1] => Array
        (
            [sight_id] => 14
            [location] => Jodhpur Jn, Jodhpur, Rajasthan, India
                  ));

$only_a1=Array(
[0]=> Array
        (
            [sight_id] => 15
            [location] => D-Kirtinagar, Jodhpur, Rajasthan, India

        ));
$only_a2=Array(
[1] => Array
        (
            [sight_id] => 16
            [location] => Jaisalmer, Rajasthan, India

        )

    [2] => Array
        (
            [sight_id] => 17
            [location] => Fort Road, Amar Sagar Pol, Jaisalmer, Rajasthan, India

        ));

Answer 1

Convert arrays to a format, where array index is the sight_id:

$b1 =array();
foreach($a1 as $x)
    $b1[$x['sight_id']] = $x['location'];

$b2 =array();
foreach($a2 as $x)
    $b2[$x['sight_id']] = $x['location'];

Calculate the differences and intersection:

$c_intersect = array_intersect_key($b1,$b2);
$c_1 = array_diff_key($b1,$b2);
$c_2 = array_diff_key($b2,$b1);

Convert arrays back to your format:

$intersect_array = array();
foreach($c_intersect as $i=>$v)
    $intersect_array[] = array('sight_id'=>$i,'location'=>$v);

$only_a1 = array();
foreach($c_1 as $i=>$v)
    $only_a1[] = array('sight_id'=>$i,'location'=>$v);

$only_a2 = array();
foreach($c_2 as $i=>$v)
    $only_a2[] = array('sight_id'=>$i,'location'=>$v);