array_partition

gistfile1.php

<?php

function array_partition($array, $callback, $preserveKeys = false) {
    $partitions = array();
    foreach($array as $key => $value) {
        $partitionName = $callback($value, $key);
        if(!array_key_exists($partitionName, $partitions)) {
            $partitions[$partitionName] = array(); 
        }
        if($preserveKeys) {
            $partitions[$partitionName][$key] = $value;
        }
        else {
            $partitions[$partitionName][] = $value;
        }
    }
    return $partitions;
}