PHPで配列から要素をランダムに抽出する方法

<?php
/*
 * $array = the array to be filtered
 * $total = the maximum number of items to return
 * $unique = whether or not to remove duplicates before getting a random list
 */
function unique_array($array, $total, $unique = true){
    $newArray = array();
    if((bool)$unique){
        $array = array_unique($array);
    }
    shuffle($array);
    $length = count($array);
    for($i = 0; $i < $total; $i++){
        if($i < $length){
            $newArray[] = $array[$i];
        }
    }
    return $newArray;
}
$phrases = array(&#39;Hello Sailor&#39;,&#39;Acid Test&#39;,&#39;Bear Garden&#39;,&#39;Botch A Job&#39;,&#39;Dark Horse&#39;,
    &#39;In The Red&#39;,&#39;Man Up&#39;,&#39;Pan Out&#39;,&#39;Quid Pro Quo&#39;,&#39;Rub It In&#39;,&#39;Turncoat&#39;,
    &#39;Yes Man&#39;,&#39;All Wet&#39;,&#39;Bag Lady&#39;,&#39;Bean Feast&#39;,&#39;Big Wig&#39;, &#39;Big Wig&#39;,&#39;Bear Garden&#39;
    ,&#39;All Wet&#39;,&#39;Quid Pro Quo&#39;,&#39;Rub It In&#39;);
print_r(unique_array($phrases, 1));
// Returns 1 result
print_r(unique_array($phrases, 5));
// Returns 5 unique results
print_r(unique_array($phrases, 5, false));
// Returns 5 results, but may have duplicates if
// there are duplicates in original array
print_r(unique_array($phrases, 100));
// Returns 100 unique results    
print_r(unique_array($phrases, 100, false));
// Returns 100 results, but may have duplicates if
// there are duplicates in original array