RandomLib - A random class

RandomLib - A random class
The class can be used to select one or a group of item(strings, objects, anything) from the entire collection of items. It include randomly select, randomly select unique.
It also include function to randomly select weighted items and randomly select unique weighted items. Weighted items are items assigned a weight, so it can show up more frequently than ones with lower weight. This could be great on making sites need reward some user more than other, or PHP games.

/*********************************
RandomLib Version 1.0
Programmed by : Chao Xu(Mgccl)
E-mail : mgcclx@gmail.com
Website : http://www.webdevlogs.com
Info : Please email me if there is any feature you want
or there is any bugs. I will fix them as soon as possible.
*********************************/

class random{
var $data = array();
function add($string,$weight=1){
$this->data[] = array('s' => $string, 'w' => $weight);
}
function optimize(){
foreach($this->data as $var){
if($new[$var['s']]){
$new[$var['s']] += $var['w'];
}else{
$new[$var['s']] = $var['w'];
}
}
unset($this->data);
foreach($new as $key=>$var){
$this->data[] = array('s' => $key, 'w' => $var);
}
}

function select($amount=1){
if($amount == 1){
$rand = array_rand($this->data);
$result = $this->data[$rand]['s'];
}else{
$i = 0;
while($i<$amount){
$result[] = $this->data[array_rand($this->data)]['s'];
++$i;
}
}
return $result;
}

function select_unique($amount=1){
if($amount == 1){
$rand = array_rand($this->data);
$result = $this->data[$rand]['s'];
}else{
$rand = array_rand($this->data, $amount);
foreach($rand as $var){
$result[] = $this->data[$var]['s'];
}
}
return $result;
}

function select_weighted($amount=1){
$count = count($this->data);
$i = 0;
$max = -1;
while($i < $count){
$max += $this->data[$i]['w'];
++$i;
}
if(1 == $amount){
$rand = mt_rand(0, $max);
$w = 0; $n = 0;
while($w <= $rand){
$w += $this->data[$n]['w'];
++$n;
}
$key = $this->data[$n-1]['s'];
}else{
$i = 0;
while($i<$amount){
$random[] = mt_rand(0, $max);
++$i;
}
sort($random);
$i = 0;
$n = 0;
$w = 0;
while($i<$amount){
while($w<=$random[$i]){
$w += $this->data[$n]['w'];
++$n;
}
$key[] = $this->data[$n-1]['s'];
++$i;
}
}
return $key;
}

function select_weighted_unique($amount=1){
$count = count($this->data);
$i = 0;
if($amount >= $count){
while($i < $count){
$return[] = $this->data[$i]['s'];
++$i;
}
return $return;
}else{
$max = -1;
while($i < $count){
$max += $this->data[$i]['w'];
++$i;
}

$i = 0;
while($i < $amount){
$max -= $sub;
$w = 0;
$n = 0;
$num = mt_rand(0,$max);
while($w <= $num){
$w += $this->data[$n]['w'];
++$n;
}
$sub = $this->data[$n-1]['w'];
$key[] = $this->data[$n-1]['s'];

unset($this->data[$n-1]);
$this->data = array_merge($this->data);
++$i;
}
return $key;
}
}
}
?>



example useage

$timeparts = explode(' ',microtime());
$starttime = $timeparts[1].substr($timeparts[0],1);
include ('class.random.php');
$random = new random;
$random->add('this have weight 1000, ', 1000);
$random->add('this have weight 1, ', 1);
$random->add('this have weight 200, ', 200);
$random->add('this have weight 500, ', 500);
?>
The random items:

one weights 1000, one weights 1, one weights 200, one weights 500

Result for randomly select 1 item:select()?>

Result for randomly select 3 item:select(3))?>

Result for randomly select 3 unique item:select_unique(3))?>

Result for weighted randomly select 1 item:select_weighted()?>

Result for weighted randomly select 3 item:select_weighted(3))?>

Result for weighted randomly select 3 unique item:select_weighted_unique(3))?>

$timeparts = explode(' ',microtime());
$endtime = $timeparts[1].substr($timeparts[0],1);
echo 'time spent',bcsub($endtime,$starttime,6);
?>