<?php /** * 按照权重进行随机选择 * * @category Zeal * @package Zeal * @subpackage Util */ class Zeal_Util_WeightedRandom { /** * 根据指定的概率范围随机返回一个结果 * * @param array $weightList 数字数组，每个值是至少包含两个值的数组， * 第一个值表示概率， * 第二个值表示概率对应的结果， * 概率必须是正整数。 * 比如： array( * array(1, array(6500,6998)), * array(2, array(9000,9999)), * array(7, array(6999,8999)), * ); * 表示 * 10%的机会返回数组array(6500,6998) , * 20%的机会返回数组array(9000,9999) , * 70%的机会返回数组array(6999,8999) , * @return mixed */ public static function get($weightList) { $weightsum = 0; $values = array(); foreach ($weightList as $val){ if(count($val) < 2){ throw new Exception( 'content array must be at least size 2!',1); } $weight = $val[0]; if(!is_int($weight) || $weight < 0){ throw new Exception( 'weight value must be positive integer!',2); } $weightsum += $weight; $values[] = $weight; } if($weightsum <= 0){ throw new Exception( 'weight sum must be integer and greater than zero!',3); } $r = mt_rand(1, $weightsum); foreach ($values as $pos=>$weight) { if ($r <= $weight){ break; } $r -= $weight; } return $weightList[$pos][1]; } }