This should really just be part of PHP

array_partition.php

<?php

// implementation

function array_partition($arr, $callable) {
    $r = array(array(), array());
    foreach ($arr as $e) {
        $r[$callable($e) ? 0 : 1][] = $e;
    }
    return $r;
}

// usage

$arr = array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9);

list($even, $odd) = array_partition($arr, function ($e) {
    return $e % 2 == 0;
});

print_r($even); // 0, 2, 4, 6, 8
print_r($odd);  // 1, 3, 5, 7, 9