PHP伪平均评分生成器优化：用最少合理票数调整目标评分

需求说明 #

现有业务场景：某素材初始评分为2.7，对应票数7票。需要将评分调整至指定目标值（例如从2.7调整至4.6），要求通过最少的合理票数达成目标，避免原脚本中调至6.0时票数激增超500的不合理情况。

原脚本代码 #

<?php

class RatingFaker
{
    private $totalRating = 10; // Maximum rating threshold (5 or 10)
    private $maxRatingGenerate = 10; // We generate maximum rating values during the passage
    private $minRatingGenerarate = 5; // Minimally generates a rating value during a pass
    private $minRatingCheck = 3.5; // The minimum acceptable threshold from which we start to act
    
    public function __construct($minRatingCheck)
    {
        $this->minRatingCheck = $minRatingCheck;
    }
    
    private function calcAverageRating($ratings = []) 
    {
        $totalWeight = 0;
        $totalReviews = 0;
    
        foreach ($ratings as $weight => $numberofReviews) {
            $WeightMultipliedByNumber = $weight * $numberofReviews;
            $totalWeight += $WeightMultipliedByNumber;
            $totalReviews += $numberofReviews;
            }
    
        //divide the total weight by total number of reviews
        $averageRating = $totalWeight / $totalReviews;
    
        return [
            'rating' => $averageRating,
            'vote_num' => $totalReviews
        ];
    }
    
    private function getRandVoters()
    {
        $randRating = rand($this->minRatingGenerarate, $this->maxRatingGenerate);
        $randVoters = rand(1, 99);
        
        return [
            $randRating => $randVoters
        ];
    }
    
    private function ratingLoop($valueList)
    {
        $valueList = array_merge($valueList, $this->getRandVoters());
        
        $newRating = $this->calcAverageRating($valueList);
        
        if($newRating['rating'] < $this->minRatingCheck) {
            $valueList = array_merge($valueList, $this->getRandVoters());
            
            return $this->ratingLoop($valueList);
        }
        
        if($newRating['rating'] > 10) {
            $newRating['rating'] = 10;
        }
        
        return [
            'rating' => round($newRating['rating'], 1),
            'sum' => round($newRating['vote_num'] * round($newRating['rating'], 1)),
            'voters' => $newRating['vote_num']
        ];
    }
    
    public function check($currentRate, $currentVoteNum)
    {
        if($currentRate < $this->minRatingCheck) {
            $rating = $this->ratingLoop([
                $currentRate => $currentVoteNum,
            ]);
        }
        
        return $rating ?? [];
    }
}

$currentRate = 2.4;
$voteNum = 88;
$oldRating = [
    'rating' => $currentRate,
    'sum' => round($voteNum * $currentRate),
    'voters' => $voteNum
];
$rating = [];

$ratingFaker = new RatingFaker(6.0);
$rating = $ratingFaker->check($currentRate, $voteNum);

echo '<pre>';
echo 'Was:';
print_r($oldRating);
echo "<br>";
echo "<br>";
echo "<br>";
echo 'Now:';
print_r($rating);
echo '</pre>';

优化后的脚本代码 #

<?php

class RatingOptimizer
{
    private $maxRating = 10; // 评分上限（支持5或10）

    /**
     * 计算达到目标评分所需的最少新增票数
     * @param float $currentRate 当前评分
     * @param int $currentVoteNum 当前票数
     * @param float $targetRate 目标评分
     * @return array 包含最终评分、总票数、总分的结果
     */
    public function adjustToTarget($currentRate, $currentVoteNum, $targetRate)
    {
        // 目标评分不能超过上限或低于0
        if ($targetRate > $this->maxRating || $targetRate < 0) {
            throw new InvalidArgumentException("目标评分必须在0到{$this->maxRating}之间");
        }
        // 当前评分已高于目标，无需调整
        if ($currentRate >= $targetRate) {
            return [
                'rating' => round($currentRate, 1),
                'voters' => $currentVoteNum,
                'sum' => round($currentRate * $currentVoteNum)
            ];
        }

        $currentTotal = $currentRate * $currentVoteNum;
        $addVoteNum = 0;

        // 计算最少需要的新增最高评分票数，确保平均评分达到目标
        do {
            $addVoteNum++;
            $newTotal = $currentTotal + $this->maxRating * $addVoteNum;
            $newTotalVotes = $currentVoteNum + $addVoteNum;
            $newAverage = $newTotal / $newTotalVotes;
        } while (round($newAverage, 1) < $targetRate);

        // 处理极端情况，避免评分超出上限
        if ($newAverage > $this->maxRating) {
            $newAverage = $this->maxRating;
        }

        return [
            'rating' => round($newAverage, 1),
            'voters' => $newTotalVotes,
            'sum' => round($newAverage * $newTotalVotes)
        ];
    }
}

// 示例使用
$currentRate = 2.7;
$currentVoteNum = 7;
$targetRate = 4.6;

$optimizer = new RatingOptimizer();
$result = $optimizer->adjustToTarget($currentRate, $currentVoteNum, $targetRate);

echo '<pre>';
echo '初始状态:' . PHP_EOL;
print_r([
    'rating' => $currentRate,
    'voters' => $currentVoteNum,
    'sum' => round($currentRate * $currentVoteNum)
]);
echo PHP_EOL . '调整后状态:' . PHP_EOL;
print_r($result);
echo '</pre>';

优化说明 #

• 目标导向调整：新增targetRate参数，直接指定需要达到的评分值，替代原脚本的阈值判断逻辑
• 最少票数计算：通过数学推导，优先添加最高评分的投票，用最少的新增票数快速提升平均评分，避免原脚本随机大量投票导致的票数激增问题
• 边界处理：增加参数合法性校验，处理目标评分超出上限、当前评分已高于目标等边界场景
• 精度控制：通过循环计算确保最终评分四舍五入后符合目标值，结果更精准

内容的提问来源于stack exchange，提问作者qubit3003