php实现概率性随机抽奖代码
发布:smiling 来源: PHP粉丝网 添加日期:2021-07-03 22:01:17 浏览: 评论:0
本文给大家分享的是使用php根据奖品的权重来实现概率性随机抽奖的代码,非常的使用,有类似需求的小伙伴,可以拿去参考下。
1、初始数据:
权重越大,抽取的几率越高
[奖品1, 权重 5], [ 奖品2, 权重6], [ 奖品3, 权重 7], [ 奖品4, 权重2]
2、处理步骤:
1)N = 5 + 6 + 7 + 2 = 20
2)然后取1-N的随机数M
3)界定各 奖品的权重范围值 奖品 1 : 1-5 ; 奖品2 : 6-11; 奖品3: 12-18; 奖品4: 19-20
4) 如果M在某个奖品的权重范围值内,标识这个奖品被抽取到
- <?php
- /**
- * 奖品
- */
- class Prize {
- # ID
- public $id = null;
- # 权重
- public $weight = null;
- # 奖品名
- public $name = null;
- # 权重范围区间起始值
- protected $start = 0;
- # 权重范围区间结束值
- protected $end = 0;
- public function __construct($id, $weight, $name) {
- if (!$id) {
- throw new Exception('奖品ID为空.');
- }
- $this->id = $id;
- $this->weight = $weight ? $weight : 0;
- $this->name = $name ? $name : '随机奖品' . $id;
- }
- # id
- public function getId() {
- return $this->id;
- }
- # 权重
- public function getWeight() {
- return $this->weight;
- }
- # 设置权重范围区间
- public function setRange($start, $end) {
- $this->start = $start;
- $this->end = $end;
- }
- # 判断随机数是否在权重范围区间
- public function inRange($num) {
- return ($num >= $this->start) && ($num <= $this->end);
- }
- }
- /**
- * 奖品池
- */
- class PrizePoll implements IteratorAggregate, Countable {
- # 奖品集
- protected $items = array();
- # 加入奖品
- public function addItem(Prize $item) {
- $this->items[$item->getId()] = $item;
- return $this;
- }
- # 删除奖品
- public function removeItem($itemId) {
- if (isset($this->items[$itemId])) {
- unset($this->items[$itemId]);
- }
- return $this;
- }
- # 更新奖品
- public function updateItem(Prize $item) {
- if (isset($this->items[$item->getId()])) {
- $this->items[$item->getId()] = $item;
- }
- return $this;
- }
- # 获取所有奖品
- public function getItems() {
- return $this->items;
- }
- # 所有所有可用奖品(如果权重为0,说明这个奖品永远不可能抽到)
- public function getVisibleItems() {
- $items = array();
- foreach ($this->items as $item) {
- if ($item->getWeight()) {
- $items[$item->getId()] = $item;
- }
- }
- return $items;
- }
- # Countable::count
- public function count() {
- return count($this->items);
- }
- # IteratorAggregate::getIterator()
- public function getIterator() {
- return new ArrayIterator($this->items);
- }
- }
- /**
- * 简单的抽奖类
- */
- class SimpleTurn {
- # 奖池
- protected $poll = null;
- public function __construct(PrizePoll $poll) {
- if ($poll) {
- $this->setPoll($poll);
- }
- }
- # 抽奖
- public function run(PrizePoll $poll) {
- $poll = $poll ? $poll : $this->poll;
- if ( ! $poll) {
- throw new Exception('奖池未初始化');
- }
- if ($poll->count() <= 0) {
- throw new Exception('奖池为空');
- }
- $items = $poll->getVisibleItems();
- if (count($items) <= 0) {
- throw new Exception('奖池为空');
- }
- $sum = 0;
- foreach ($items as $item) {
- $start = $sum + 1;
- $sum += $item->getWeight();
- $end = $sum;
- # 设置奖品的权重范围区间
- $item->setRange($start, $end);
- }
- # 随机数
- $rand = $this->getRandNum(1, $sum);
- # 区间段判断
- foreach ($items as $item) {
- if ($item->inRange($rand)) {
- return $item;
- }
- }
- return null;
- }
- # 获取随机数
- public function getRandNum($min, $max) {
- return mt_rand($min ? $min : 1, $max);
- }
- # 设置奖池
- public function setPoll(PrizePoll $poll) {
- $this->poll = $poll;
- }
- }
- # 示例
- try {
- $prizePoll = new PrizePoll();
- $prizePoll->addItem(new Prize(1, 5))
- ->addItem(new Prize(2, 6))
- ->addItem(new Prize(3, 7))
- ->addItem(new Prize(4, 2));
- $turn = new SimpleTurn($prizePoll);
- $prize = $turn->run();
- var_dump($prize);
- } catch (Exception $e) {
- print_r($e);
- }
Tags: php概率性随机抽奖
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