php从数组中随机选择若干不重复元素的方法

<?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;
}
$phrases = array('hello sailor','acid test','bear garden','botch a job','dark horse',
    'in the red','man up','pan out','quid pro quo','rub it in','turncoat',
    'yes man','all wet','bag lady','bean feast','big wig', 'big wig','bear garden'
    ,'all wet','quid pro quo','rub it in');
print_r(unique_array($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