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run code in 300+ PHP versions simultaneously

@ 2018-10-19T11:33:15Z

<?php
$array = array(
        array(
            'id'         => 12,
            '_from'      => 1,
            '_to'        => 2
        ),
        array(
            'id'         => 13,
            '_from'      => 4,
            '_to'        => 2
        ),
        array(
            'id'         => 14,
            '_from'      => 2,
            '_to'        => 1
        ),
    );
    $newArray = [];
    foreach ($array as $item) {
        $uniqueRecordKey = $item['_from'].'-'.$item['_to'];
        $oppositeRecordKey = $item['_to'].'-'.$item['_from'];

        //If exists record from the opposite and new ID is greater than previous put
        if (isset($newArray[$oppositeRecordKey])) {
            $newArray[$oppositeRecordKey] = $item;
            continue; //Do not append to the end
        }

        $newArray[$uniqueRecordKey] = $item;
    }

    var_dump($newArray);

Output for 5.6.38, 7.1.0 - 7.1.23, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12: array(2) { ["1-2"]=> array(3) { ["id"]=> int(14) ["_from"]=> int(2) ["_to"]=> int(1) } ["4-2"]=> array(3) { ["id"]=> int(13) ["_from"]=> int(4) ["_to"]=> int(2) } }

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176.03 ms | 408 KiB | 5 Q