js數(shù)組實(shí)現(xiàn)權(quán)重概率分配

/**
* js數(shù)組實(shí)現(xiàn)權(quán)重概率分配
* @param Array arr js數(shù)組，參數(shù)類型[Object,Object,Object……]
* @return Array 返回一個(gè)隨機(jī)元素，概率為其percent/所有percent之和，參數(shù)類型Object
* @author shuiguang
*/
function weight_rand(arr){
 //參數(shù)arr元素必須含有percent屬性，參考如下所示
 /*
 var arr = [{
 name : '1',
 percent : 1
 }, {
 name : '2',
 percent : 2
 }, {
 name : '3',
 percent : 1
 }, {
 name : '4',
 percent : 2
 }
 ];
 */
 var total = 0;
 var i, j, percent;
 //下標(biāo)標(biāo)記數(shù)組，按照上面的例子，單倍情況下其組成為[1,2,2,3,4,4]
 var index = new Array();
 for (i = 0; i < arr.length; i++) {
 //判斷元素的權(quán)重，為了實(shí)現(xiàn)小數(shù)權(quán)重，先將所有的值放大100倍
 percent = 'undefined' != typeof(arr[i].percent) ? parseInt(arr[i].percent*100) : 0;
 for (j = 0; j < percent; j++) {
 index.push(i);
 }
 total += percent;
 }
 //隨機(jī)數(shù)值，其值介于0-5的整數(shù)
 var rand = Math.floor(Math.random() * total);
 return arr[index[rand]];
}

/**
* js數(shù)組實(shí)現(xiàn)權(quán)重概率分配，支持?jǐn)?shù)字比模式(支持2位小數(shù))和百分比模式(不支持小數(shù)，最后一個(gè)元素多退少補(bǔ))
* @param Array arr js數(shù)組，參數(shù)類型[Object,Object,Object……]
* @return Array 返回一個(gè)隨機(jī)元素，概率為其weight/所有weight之和，參數(shù)類型Object
* @author shuiguang
*/
function weight_rand(arr){
	//參數(shù)arr元素必須含有weight屬性，參考如下所示
	//var arr=[{name:'1',weight:1.5},{name:'2',weight:2.5},{name:'3',weight:3.5}];
	//var arr=[{name:'1',weight:'15%'},{name:'2',weight:'25%'},{name:'3',weight:'35%'}];
	//求出最大公約數(shù)以計(jì)算縮小倍數(shù)，perMode為百分比模式
	var per;
	var maxNum = 0;
	var perMode = false;
	//自定義Math求最小公約數(shù)方法
	Math.gcd = function(a,b){
	var min = Math.min(a,b);
	var max = Math.max(a,b);
	var result = 1;
	if(a === 0 || b===0){
	return max;
	}
	for(var i=min; i>=1; i--){
	if(min % i === 0 && max % i === 0){
	result = i;
	break;
	}
	}
	return result;
	};
	
	//使用clone元素對(duì)象拷貝仍然會(huì)造成浪費(fèi)，但是使用權(quán)重?cái)?shù)組對(duì)應(yīng)關(guān)系更省內(nèi)存
	var weight_arr = new Array();
	for (i = 0; i < arr.length; i++) {
	if('undefined' != typeof(arr[i].weight))
	{
	if(arr[i].weight.toString().indexOf('%') !== -1) {
	per = Math.floor(arr[i].weight.toString().replace('%',''));
	perMode = true;
	}else{
	per = Math.floor(arr[i].weight*100);
	}
	}else{
	per = 0;
	}
	weight_arr[i] = per;
	maxNum = Math.gcd(maxNum, per);
	}
	//數(shù)字比模式，3:5:7，其組成[0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2]
	//百分比模式，元素所占百分比為15%，25%，35%
	var index = new Array();
	var total = 0;
	var len = 0;
	if(perMode){
	for (i = 0; i < arr.length; i++) {
	//len表示存儲(chǔ)arr下標(biāo)的數(shù)據(jù)塊長(zhǎng)度，已優(yōu)化至最小整數(shù)形式減小索引數(shù)組的長(zhǎng)度
	len = weight_arr[i];
	for (j = 0; j < len; j++){
	//超過(guò)100%跳出，后面的舍棄
	if(total >= 100){
	break;
	}
	index.push(i);
	total++;
	}
	}
	//使用最后一個(gè)元素補(bǔ)齊100%
	while(total < 100){
	index.push(arr.length-1);
	total++;
	}
	}else{
	for (i = 0; i < arr.length; i++) {
	//len表示存儲(chǔ)arr下標(biāo)的數(shù)據(jù)塊長(zhǎng)度，已優(yōu)化至最小整數(shù)形式減小索引數(shù)組的長(zhǎng)度
	len = weight_arr[i]/maxNum;
	for (j = 0; j < len; j++){
	index.push(i);
	}
	total += len;
	}
	}
	//隨機(jī)數(shù)值，其值為0-11的整數(shù)，數(shù)據(jù)塊根據(jù)權(quán)重分塊
	var rand = Math.floor(Math.random()*total);
	//console.log(index);
	return arr[index[rand]];
}

var arr=[{name:'1',weight:1.5},{name:'2',weight:2.5},{name:'3',weight:3.5}];
console.log(weight_rand(arr));
var arr=[{name:'1',weight:'15%'},{name:'2',weight:'25%'},{name:'3',weight:'35%'}];
console.log(weight_rand(arr));
var prize_arr = [
	{'id':1, 'prize':'平板電腦', 'weight':1},
	{'id':2, 'prize':'數(shù)碼相機(jī)', 'weight':2},
	{'id':3, 'prize':'音箱設(shè)備', 'weight':10},
	{'id':4, 'prize':'4G優(yōu)盤', 'weight':12},
	{'id':5, 'prize':'10Q幣', 'weight':22},
	{'id':6, 'prize':'下次沒(méi)準(zhǔn)就能中哦', 'weight':50} 
];

var times = 100000;
var prize;
var pingban = 0;
var shuma = 0;
var yinxiang = 0;
var youpan = 0;
var qb = 0;
var xc = 0;
var start = new Date().getTime();

for($i=0; $i<times; $i++){
	prize = weight_rand(prize_arr);
	if(prize.prize == '平板電腦')
	{
	pingban++;
	}else if(prize.prize == '數(shù)碼相機(jī)'){
	shuma++;
	}else if(prize.prize == '音箱設(shè)備'){
	yinxiang++;
	}else if(prize.prize == '4G優(yōu)盤'){
	youpan++;
	}else if(prize.prize == '10Q幣'){
	qb++;
	}else if(prize.prize == '下次沒(méi)準(zhǔn)就能中哦'){
	xc++;
	}
}

var stop = new Date().getTime();
console.log('平板電腦：'+pingban/times+', 數(shù)碼相機(jī)：'+shuma/times+', 音箱設(shè)備：'+yinxiang/times+', 4G優(yōu)盤：'+youpan/times+', 10Q幣：'+qb/times+', 下次沒(méi)準(zhǔn)就能中哦：'+xc/times);
console.log('耗費(fèi)時(shí)間：'+(stop-start)/1000+'秒');

/**
* php數(shù)組實(shí)現(xiàn)權(quán)重概率分配，支持?jǐn)?shù)字比模式(支持2位小數(shù))和百分比模式(不支持小數(shù)，最后一個(gè)元素多退少補(bǔ))
* @param array $arr php數(shù)組，參數(shù)類型array(array(),array(),array()……)
* @return array 返回一個(gè)隨機(jī)元素，概率為其percent/所有percent之和，參數(shù)類型array()
* @author shuiguang
*/
function weight_rand($arr)
{
 //參數(shù)arr元素必須含有percent屬性，參考如下所示
 //$arr=array(array('name'=>'1','weight'=>1.5),array('name'=>'2','weight'=>1.5),array('name'=>'3','weight'=>1.5));
 //$arr=array(array('name'=>'1','weight'=>'15%'),array('name'=>'2','weight'=>'25%'),array('name'=>'3','weight'=>'35%'));
 //求出最大公約數(shù)以計(jì)算縮小倍數(shù)，perMode為百分比模式
 $perMode = false;
 $maxNum = 0;
 //自定義求最小公約數(shù)方法
 $gcd = function($a, $b)
 {
 $min = min($a, $b);
 $max = max($a, $b);
 $result = 1;
 if($a === 0 || $b === 0)
 {
 return $max;
 }
 for($i=$min; $i>=1; $i--)
 {
 if($min % $i === 0 && $max % $i === 0)
 {
 $result = $i;
 break;
 }
 }
 return $result;
 };
 //使用傳地址可能會(huì)影響后面的結(jié)果，但是使用權(quán)重?cái)?shù)組對(duì)應(yīng)關(guān)系更省內(nèi)存
 $weight_arr = array();
 $arr_len = count($arr);
 for($i=0; $i<$arr_len; $i++)
 {
 if(isset($arr[$i]['weight']))
 {
 if(strpos($arr[$i]['weight'], '%') !== false)
 {
 $per = floor(str_replace('%', '', $arr[$i]['weight']));
 $perMode = true;
 }else{
 $per = floor($arr[$i]['weight']*100);
 }
 }else{
 $per = 0;
 }
 $weight_arr[$i] = $per;
 $maxNum = call_user_func($gcd, $maxNum, $per);
 }
 //數(shù)字比模式，3:5:7，其組成[0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2]
 //百分比模式，元素所占百分比為15%，25%，35%
 $index = array();
 $total = 0;
 if($perMode)
 {
 for($i=0; $i<$arr_len; $i++)
 {
 //$len表示存儲(chǔ)$arr下標(biāo)的數(shù)據(jù)塊長(zhǎng)度，已優(yōu)化至最小整數(shù)形式減小索引數(shù)組的長(zhǎng)度
 $len = $weight_arr[$i];
 for ($j = 0; $j < $len; $j++)
 {
 //超過(guò)100%跳出，后面的舍棄
 if($total >= 100)
 {
 break;
 }
 $index[] = $i;
 $total++;
 }
 }
 //使用最后一個(gè)元素補(bǔ)齊100%
 while($total < 100)
 {
 $index[] = $arr_len-1;
 $total++;
 }
 }else{
 for($i=0; $i<$arr_len; $i++)
 {
 //len表示存儲(chǔ)arr下標(biāo)的數(shù)據(jù)塊長(zhǎng)度，已優(yōu)化至最小整數(shù)形式減小索引數(shù)組的長(zhǎng)度
 $len = $weight_arr[$i]/$maxNum;
 for ($j = 0; $j < $len; $j++)
 {
 $index[] = $i;
 }
 $total += $len;
 }
 }
 //隨機(jī)數(shù)值，其值為0-11的整數(shù)，數(shù)據(jù)塊根據(jù)權(quán)重分塊
 $rand = floor(mt_rand(0, $total));
	//修復(fù)php隨機(jī)函數(shù)可以取臨界值造成的bug
 $rand = $rand == $total ? $total-1 : $rand;
 return $arr[$index[$rand]];
}

$arr=array(array('name'=>'1','weight'=>1.5),array('name'=>'2','weight'=>1.5),array('name'=>'3','weight'=>1.5));
p(weight_rand($arr));
$arr=array(array('name'=>'1','weight'=>'15%'),array('name'=>'2','weight'=>'25%'),array('name'=>'3','weight'=>'35%'));
p(weight_rand($arr));

$prize_arr = array(
	'0' => array('id'=>1, 'prize'=>'平板電腦', 'weight'=>1),
	'1' => array('id'=>2, 'prize'=>'數(shù)碼相機(jī)', 'weight'=>5),
	'2' => array('id'=>3, 'prize'=>'音箱設(shè)備', 'weight'=>10),
	'3' => array('id'=>4, 'prize'=>'4G優(yōu)盤', 'weight'=>12),
	'4' => array('id'=>5, 'prize'=>'10Q幣', 'weight'=>22),
	'5' => array('id'=>6, 'prize'=>'下次沒(méi)準(zhǔn)就能中哦', 'weight'=>50),
);

$start = time();
$result = array();
$times = 100000;
for($i=0; $i<$times; $i++)
{
	$row = weight_rand($prize_arr);
	if(array_key_exists($row['prize'], $result))
	{
	$result[$row['prize']] ++;
	}else{
	$result[$row['prize']] = 1;
	}
}
$cost = time() - $start;


p($result);
p('耗費(fèi)時(shí)間：'.$cost.'秒');
function p($var)
{
 echo "<pre>";
 if($var === false)
 {
 echo 'false';
 }else if($var === ''){
 print_r("''");
 }else{
 print_r($var);
 }
 echo "</pre>";
}