unset array keys based on comparing two array values in the same array

Question

I'm trying to figure out a simple way to remove/unset duplicate array values based off a higher secondary value in the array in php.

Here's an simple example of the original array.

$ar = array(
    array('pid'=>'544', 'discount'=>'26.00','promo_id'=>'9807'),
    array('pid'=>'544', 'discount'=>'15.00','promo_id'=>'9821'),
    array('pid'=>'544', 'discount'=>'21.00','promo_id'=>'9811'),
    array('pid'=>'2965','discount'=>'25.00','promo_id'=>'9810'),
    array('pid'=>'2965','discount'=>'30.50','promo_id'=>'9809'),
    array('pid'=>'1866','discount'=>'30.00','promo_id'=>'9810'),
    array('pid'=>'1866','discount'=>'25.50','promo_id'=>'9809')
);

This would be the NEW array that I would like to get.

$ar = array(
    array('pid'=>'544', 'discount'=>'26.00','promo_id'=>'9807'),
    array('pid'=>'2965','discount'=>'30.50','promo_id'=>'9809'),
    array('pid'=>'1866','discount'=>'30.00','promo_id'=>'9810'),
);

These would be the keys that have been removed.

//array('pid'=>'1866','discount'=>'25.50','promo_id'=>'9809')  Removed!
//array('pid'=>'544', 'discount'=>'21.00','promo_id'=>'9811'), Removed!
//array('pid'=>'544', 'discount'=>'15.00','promo_id'=>'9821'), Removed!
//array('pid'=>'2965','discount'=>'25.00','promo_id'=>'9810'), Removed!

I would like to remove any duplicate values of the 'pid' by KEEPING the highest value of the 'discount'.

The array may have more than two keys that have the same 'pid' but they would never have the same 'pid' and 'promo_id'.

Hopefully there is an easy solution for this.

EDIT:

Here what I've been trying.

foreach($ar as $tkey => $v) {

    $tPID = $v['pid'];
    $tDISC = $v['discount'];

    if ($tPID) {

        $key = array_search($tPID, array_column($ar, 'pid'));
        $aPID  = $ar[$key]['pid'];
        $aTPRD = $ar[$key]['discount'];

        if ($aTPRD < $tDISC) {
            echo '(UN:'.$tkey.')'; unset($ar[$tkey]);
        }else
        if ($aTPRD > $tDISC) {
            echo '(UN:'.$key.')'; unset($ar[$key]);
        }else{echo 'else'; }

    }
}

Take a look at php.net/manual/en/function.array-intersect-ukey.php. You can write a callback and compare pid in it. — dudeman
– dudeman, Commented Mar 6, 2015 at 20:17

Ryan Vincent · Accepted Answer · 2015-03-06 22:56:20Z

1

Create an output array, keyed on 'pid' that holds the highest discount entry found for the pid.

Extract the output array using 'array_values'.

Working code at Codepad.org...

There was a suggested edit to the code to make it shorter. However, i try to ensure the code is easy to understand rather than try and make it the minimum amount of code. This code is quite efficient as it is anyway.

 <?php //

$ar = array(
    array('pid'=>'544', 'discount'=>'26.00','promo_id'=>'9807'),
    array('pid'=>'544', 'discount'=>'15.00','promo_id'=>'9821'),
    array('pid'=>'544', 'discount'=>'21.00','promo_id'=>'9811'),
    array('pid'=>'2965','discount'=>'25.00','promo_id'=>'9810'),
    array('pid'=>'2965','discount'=>'30.50','promo_id'=>'9809'),
    array('pid'=>'1866','discount'=>'30.00','promo_id'=>'9810'),
    array('pid'=>'1866','discount'=>'25.50','promo_id'=>'9809')
);

$outUnique = array();

foreach ($ar as $entry) {

    $curPid = $entry['pid'];

    if (isset($outUnique[$curPid])) { // check the discount

        if ($entry['discount'] > $outUnique[$curPid]['discount']) {
            $outUnique[$curPid] = $entry;
        }
    }
    else { // add to the output

        $outUnique[$curPid] = $entry;
    }
}
// show the entries
var_dump(array_values($outUnique));

edited Mar 6, 2015 at 22:56

answered Mar 6, 2015 at 20:44

Ryan Vincent

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1 Comment

Monty Over a year ago

That's great! Thanks for that, its much more simple than I was making it.

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