PHP中奖概率实现

$prize_arr = array(
            '0' => array('id'=>1,'prize'=>'elm_1','rate'=>1),
            '1' => array('id'=>2,'prize'=>'elm_2','rate'=>14),
            '2' => array('id'=>3,'prize'=>'elm_3','rate'=>20),
            '3' => array('id'=>4,'prize'=>'elm_4','rate'=>30),
            '4' => array('id'=>5,'prize'=>'elm_5','rate'=>35),
        );

        function get_rand($proArr) {
            $result = '';
            //概率数组的总概率精度
            $proSum = array_sum($proArr);
            //概率数组循环
            foreach ($proArr as $key => $proCur) {
                $randNum = mt_rand(1, $proSum);
                if ($randNum <= $proCur) {
                    $result = $key;
                    break;
                } else {
                    $proSum -= $proCur;
                }
            }
            unset ($proArr);
            return $result;
        }



        /*
         * 每次前端页面的请求，PHP循环奖项设置数组，
         * 通过概率计算函数get_rand获取抽中的奖项id。
         */
        foreach ($prize_arr as $key => $val) {
            $arr[$val['id']] = $val['rate'];
        }
        $rid = get_rand($arr); //根据概率获取奖项id

        $res = $prize_arr[$rid-1]['prize']; //中奖项

        print_r($res);