pryley / site-reviews

plugin/Modules/Rating.php

Indentation +191 added lines, -191 removed lines

@@ -4,207 +4,207 @@
 
 class Rating
 {
-    /**
-     * The more sure we are of the confidence interval (the higher the confidence level), the less
-     * precise the estimation will be as the margin for error will be higher.
-     * @see http://homepages.math.uic.edu/~bpower6/stat101/Confidence%20Intervals.pdf
-     * @see https://www.thecalculator.co/math/Confidence-Interval-Calculator-210.html
-     * @see https://www.youtube.com/watch?v=grodoLzThy4
-     * @see https://en.wikipedia.org/wiki/Standard_score
-     * @var array
-     */
-    const CONFIDENCE_LEVEL_Z_SCORES = [
-        50 => 0.67449,
-        70 => 1.04,
-        75 => 1.15035,
-        80 => 1.282,
-        85 => 1.44,
-        90 => 1.64485,
-        92 => 1.75,
-        95 => 1.95996,
-        96 => 2.05,
-        97 => 2.17009,
-        98 => 2.326,
-        99 => 2.57583,
-        '99.5' => 2.81,
-        '99.8' => 3.08,
-        '99.9' => 3.29053,
-    ];
+	/**
+	 * The more sure we are of the confidence interval (the higher the confidence level), the less
+	 * precise the estimation will be as the margin for error will be higher.
+	 * @see http://homepages.math.uic.edu/~bpower6/stat101/Confidence%20Intervals.pdf
+	 * @see https://www.thecalculator.co/math/Confidence-Interval-Calculator-210.html
+	 * @see https://www.youtube.com/watch?v=grodoLzThy4
+	 * @see https://en.wikipedia.org/wiki/Standard_score
+	 * @var array
+	 */
+	const CONFIDENCE_LEVEL_Z_SCORES = [
+		50 => 0.67449,
+		70 => 1.04,
+		75 => 1.15035,
+		80 => 1.282,
+		85 => 1.44,
+		90 => 1.64485,
+		92 => 1.75,
+		95 => 1.95996,
+		96 => 2.05,
+		97 => 2.17009,
+		98 => 2.326,
+		99 => 2.57583,
+		'99.5' => 2.81,
+		'99.8' => 3.08,
+		'99.9' => 3.29053,
+	];
 
-    /**
-     * @var int
-     */
-    const MAX_RATING = 5;
+	/**
+	 * @var int
+	 */
+	const MAX_RATING = 5;
 
-    /**
-     * @var int
-     */
-    const MIN_RATING = 1;
+	/**
+	 * @var int
+	 */
+	const MIN_RATING = 1;
 
-    /**
-     * @param int $roundBy
-     * @return float
-     */
-    public function getAverage(array $ratingCounts, $roundBy = 1)
-    {
-        $average = array_sum($ratingCounts);
-        if ($average > 0) {
-            $average = $this->getTotalSum($ratingCounts) / $average;
-        }
-        $roundedAverage = round($average, intval($roundBy));
-        return floatval(apply_filters('site-reviews/rating/average', $roundedAverage, $ratingCounts, $average));
-    }
+	/**
+	 * @param int $roundBy
+	 * @return float
+	 */
+	public function getAverage(array $ratingCounts, $roundBy = 1)
+	{
+		$average = array_sum($ratingCounts);
+		if ($average > 0) {
+			$average = $this->getTotalSum($ratingCounts) / $average;
+		}
+		$roundedAverage = round($average, intval($roundBy));
+		return floatval(apply_filters('site-reviews/rating/average', $roundedAverage, $ratingCounts, $average));
+	}
 
-    /**
-     * Get the lower bound for up/down ratings
-     * Method receives an up/down ratings array: [1, -1, -1, 1, 1, -1].
-     * @see http://www.evanmiller.org/how-not-to-sort-by-average-rating.html
-     * @see https://news.ycombinator.com/item?id=10481507
-     * @see https://dataorigami.net/blogs/napkin-folding/79030467-an-algorithm-to-sort-top-comments
-     * @see http://julesjacobs.github.io/2015/08/17/bayesian-scoring-of-ratings.html
-     * @param int $confidencePercentage
-     * @return int|float
-     */
-    public function getLowerBound(array $upDownCounts = [0, 0], $confidencePercentage = 95)
-    {
-        $numRatings = array_sum($upDownCounts);
-        if ($numRatings < 1) {
-            return 0;
-        }
-        $z = static::CONFIDENCE_LEVEL_Z_SCORES[$confidencePercentage];
-        $phat = 1 * $upDownCounts[1] / $numRatings;
-        return ($phat + $z * $z / (2 * $numRatings) - $z * sqrt(($phat * (1 - $phat) + $z * $z / (4 * $numRatings)) / $numRatings)) / (1 + $z * $z / $numRatings);
-    }
+	/**
+	 * Get the lower bound for up/down ratings
+	 * Method receives an up/down ratings array: [1, -1, -1, 1, 1, -1].
+	 * @see http://www.evanmiller.org/how-not-to-sort-by-average-rating.html
+	 * @see https://news.ycombinator.com/item?id=10481507
+	 * @see https://dataorigami.net/blogs/napkin-folding/79030467-an-algorithm-to-sort-top-comments
+	 * @see http://julesjacobs.github.io/2015/08/17/bayesian-scoring-of-ratings.html
+	 * @param int $confidencePercentage
+	 * @return int|float
+	 */
+	public function getLowerBound(array $upDownCounts = [0, 0], $confidencePercentage = 95)
+	{
+		$numRatings = array_sum($upDownCounts);
+		if ($numRatings < 1) {
+			return 0;
+		}
+		$z = static::CONFIDENCE_LEVEL_Z_SCORES[$confidencePercentage];
+		$phat = 1 * $upDownCounts[1] / $numRatings;
+		return ($phat + $z * $z / (2 * $numRatings) - $z * sqrt(($phat * (1 - $phat) + $z * $z / (4 * $numRatings)) / $numRatings)) / (1 + $z * $z / $numRatings);
+	}
 
-    /**
-     * @return int|float
-     */
-    public function getOverallPercentage(array $ratingCounts)
-    {
-        return round($this->getAverage($ratingCounts) * 100 / glsr()->constant('MAX_RATING', __CLASS__), 2);
-    }
+	/**
+	 * @return int|float
+	 */
+	public function getOverallPercentage(array $ratingCounts)
+	{
+		return round($this->getAverage($ratingCounts) * 100 / glsr()->constant('MAX_RATING', __CLASS__), 2);
+	}
 
-    /**
-     * @return array
-     */
-    public function getPercentages(array $ratingCounts)
-    {
-        $total = array_sum($ratingCounts);
-        foreach ($ratingCounts as $index => $count) {
-            if (empty($count)) {
-                continue;
-            }
-            $ratingCounts[$index] = $count / $total * 100;
-        }
-        return $this->getRoundedPercentages($ratingCounts);
-    }
+	/**
+	 * @return array
+	 */
+	public function getPercentages(array $ratingCounts)
+	{
+		$total = array_sum($ratingCounts);
+		foreach ($ratingCounts as $index => $count) {
+			if (empty($count)) {
+				continue;
+			}
+			$ratingCounts[$index] = $count / $total * 100;
+		}
+		return $this->getRoundedPercentages($ratingCounts);
+	}
 
-    /**
-     * @return float
-     */
-    public function getRanking(array $ratingCounts)
-    {
-        return floatval(apply_filters('site-reviews/rating/ranking',
-            $this->getRankingUsingImdb($ratingCounts),
-            $ratingCounts,
-            $this
-        ));
-    }
+	/**
+	 * @return float
+	 */
+	public function getRanking(array $ratingCounts)
+	{
+		return floatval(apply_filters('site-reviews/rating/ranking',
+			$this->getRankingUsingImdb($ratingCounts),
+			$ratingCounts,
+			$this
+		));
+	}
 
-    /**
-     * Get the bayesian ranking for an array of reviews
-     * This formula is the same one used by IMDB to rank their top 250 films.
-     * @see https://www.xkcd.com/937/
-     * @see https://districtdatalabs.silvrback.com/computing-a-bayesian-estimate-of-star-rating-means
-     * @see http://fulmicoton.com/posts/bayesian_rating/
-     * @see https://stats.stackexchange.com/questions/93974/is-there-an-equivalent-to-lower-bound-of-wilson-score-confidence-interval-for-va
-     * @param int $confidencePercentage
-     * @return int|float
-     */
-    public function getRankingUsingImdb(array $ratingCounts, $confidencePercentage = 70)
-    {
-        $avgRating = $this->getAverage($ratingCounts);
-        // Represents a prior (your prior opinion without data) for the average star rating. A higher prior also means a higher margin for error.
-        // This could also be the average score of all items instead of a fixed value.
-        $bayesMean = ($confidencePercentage / 100) * glsr()->constant('MAX_RATING', __CLASS__); // prior, 70% = 3.5
-        // Represents the number of ratings expected to begin observing a pattern that would put confidence in the prior.
-        $bayesMinimal = 10; // confidence
-        $numOfReviews = array_sum($ratingCounts);
-        return $avgRating > 0
-            ? (($bayesMinimal * $bayesMean) + ($avgRating * $numOfReviews)) / ($bayesMinimal + $numOfReviews)
-            : 0;
-    }
+	/**
+	 * Get the bayesian ranking for an array of reviews
+	 * This formula is the same one used by IMDB to rank their top 250 films.
+	 * @see https://www.xkcd.com/937/
+	 * @see https://districtdatalabs.silvrback.com/computing-a-bayesian-estimate-of-star-rating-means
+	 * @see http://fulmicoton.com/posts/bayesian_rating/
+	 * @see https://stats.stackexchange.com/questions/93974/is-there-an-equivalent-to-lower-bound-of-wilson-score-confidence-interval-for-va
+	 * @param int $confidencePercentage
+	 * @return int|float
+	 */
+	public function getRankingUsingImdb(array $ratingCounts, $confidencePercentage = 70)
+	{
+		$avgRating = $this->getAverage($ratingCounts);
+		// Represents a prior (your prior opinion without data) for the average star rating. A higher prior also means a higher margin for error.
+		// This could also be the average score of all items instead of a fixed value.
+		$bayesMean = ($confidencePercentage / 100) * glsr()->constant('MAX_RATING', __CLASS__); // prior, 70% = 3.5
+		// Represents the number of ratings expected to begin observing a pattern that would put confidence in the prior.
+		$bayesMinimal = 10; // confidence
+		$numOfReviews = array_sum($ratingCounts);
+		return $avgRating > 0
+			? (($bayesMinimal * $bayesMean) + ($avgRating * $numOfReviews)) / ($bayesMinimal + $numOfReviews)
+			: 0;
+	}
 
-    /**
-     * The quality of a 5 star rating depends not only on the average number of stars but also on
-     * the number of reviews. This method calculates the bayesian ranking of a page by its number
-     * of reviews and their rating.
-     * @see http://www.evanmiller.org/ranking-items-with-star-ratings.html
-     * @see https://stackoverflow.com/questions/1411199/what-is-a-better-way-to-sort-by-a-5-star-rating/1411268
-     * @see http://julesjacobs.github.io/2015/08/17/bayesian-scoring-of-ratings.html
-     * @param int $confidencePercentage
-     * @return float
-     */
-    public function getRankingUsingZScores(array $ratingCounts, $confidencePercentage = 90)
-    {
-        $ratingCountsSum = array_sum($ratingCounts) + glsr()->constant('MAX_RATING', __CLASS__);
-        $weight = $this->getWeight($ratingCounts, $ratingCountsSum);
-        $weightPow2 = $this->getWeight($ratingCounts, $ratingCountsSum, true);
-        $zScore = static::CONFIDENCE_LEVEL_Z_SCORES[$confidencePercentage];
-        return $weight - $zScore * sqrt(($weightPow2 - pow($weight, 2)) / ($ratingCountsSum + 1));
-    }
+	/**
+	 * The quality of a 5 star rating depends not only on the average number of stars but also on
+	 * the number of reviews. This method calculates the bayesian ranking of a page by its number
+	 * of reviews and their rating.
+	 * @see http://www.evanmiller.org/ranking-items-with-star-ratings.html
+	 * @see https://stackoverflow.com/questions/1411199/what-is-a-better-way-to-sort-by-a-5-star-rating/1411268
+	 * @see http://julesjacobs.github.io/2015/08/17/bayesian-scoring-of-ratings.html
+	 * @param int $confidencePercentage
+	 * @return float
+	 */
+	public function getRankingUsingZScores(array $ratingCounts, $confidencePercentage = 90)
+	{
+		$ratingCountsSum = array_sum($ratingCounts) + glsr()->constant('MAX_RATING', __CLASS__);
+		$weight = $this->getWeight($ratingCounts, $ratingCountsSum);
+		$weightPow2 = $this->getWeight($ratingCounts, $ratingCountsSum, true);
+		$zScore = static::CONFIDENCE_LEVEL_Z_SCORES[$confidencePercentage];
+		return $weight - $zScore * sqrt(($weightPow2 - pow($weight, 2)) / ($ratingCountsSum + 1));
+	}
 
-    /**
-     * @param int $target
-     * @return array
-     */
-    protected function getRoundedPercentages(array $percentages, $totalPercent = 100)
-    {
-        array_walk($percentages, function (&$percent, $index) {
-            $percent = [
-                'index' => $index,
-                'percent' => floor($percent),
-                'remainder' => fmod($percent, 1),
-            ];
-        });
-        $indexes = glsr_array_column($percentages, 'index');
-        $remainders = glsr_array_column($percentages, 'remainder');
-        array_multisort($remainders, SORT_DESC, SORT_STRING, $indexes, SORT_DESC, $percentages);
-        $i = 0;
-        if (array_sum(glsr_array_column($percentages, 'percent')) > 0) {
-            while (array_sum(glsr_array_column($percentages, 'percent')) < $totalPercent) {
-                ++$percentages[$i]['percent'];
-                ++$i;
-            }
-        }
-        array_multisort($indexes, SORT_DESC, $percentages);
-        return array_combine($indexes, glsr_array_column($percentages, 'percent'));
-    }
+	/**
+	 * @param int $target
+	 * @return array
+	 */
+	protected function getRoundedPercentages(array $percentages, $totalPercent = 100)
+	{
+		array_walk($percentages, function (&$percent, $index) {
+			$percent = [
+				'index' => $index,
+				'percent' => floor($percent),
+				'remainder' => fmod($percent, 1),
+			];
+		});
+		$indexes = glsr_array_column($percentages, 'index');
+		$remainders = glsr_array_column($percentages, 'remainder');
+		array_multisort($remainders, SORT_DESC, SORT_STRING, $indexes, SORT_DESC, $percentages);
+		$i = 0;
+		if (array_sum(glsr_array_column($percentages, 'percent')) > 0) {
+			while (array_sum(glsr_array_column($percentages, 'percent')) < $totalPercent) {
+				++$percentages[$i]['percent'];
+				++$i;
+			}
+		}
+		array_multisort($indexes, SORT_DESC, $percentages);
+		return array_combine($indexes, glsr_array_column($percentages, 'percent'));
+	}
 
-    /**
-     * @return int
-     */
-    protected function getTotalSum(array $ratingCounts)
-    {
-        return array_reduce(array_keys($ratingCounts), function ($carry, $index) use ($ratingCounts) {
-            return $carry + ($index * $ratingCounts[$index]);
-        });
-    }
+	/**
+	 * @return int
+	 */
+	protected function getTotalSum(array $ratingCounts)
+	{
+		return array_reduce(array_keys($ratingCounts), function ($carry, $index) use ($ratingCounts) {
+			return $carry + ($index * $ratingCounts[$index]);
+		});
+	}
 
-    /**
-     * @param int|float $ratingCountsSum
-     * @param bool $powerOf2
-     * @return float
-     */
-    protected function getWeight(array $ratingCounts, $ratingCountsSum, $powerOf2 = false)
-    {
-        return array_reduce(array_keys($ratingCounts),
-            function ($count, $rating) use ($ratingCounts, $ratingCountsSum, $powerOf2) {
-                $ratingLevel = $powerOf2
-                    ? pow($rating, 2)
-                    : $rating;
-                return $count + ($ratingLevel * ($ratingCounts[$rating] + 1)) / $ratingCountsSum;
-            }
-        );
-    }
+	/**
+	 * @param int|float $ratingCountsSum
+	 * @param bool $powerOf2
+	 * @return float
+	 */
+	protected function getWeight(array $ratingCounts, $ratingCountsSum, $powerOf2 = false)
+	{
+		return array_reduce(array_keys($ratingCounts),
+			function ($count, $rating) use ($ratingCounts, $ratingCountsSum, $powerOf2) {
+				$ratingLevel = $powerOf2
+					? pow($rating, 2)
+					: $rating;
+				return $count + ($ratingLevel * ($ratingCounts[$rating] + 1)) / $ratingCountsSum;
+			}
+		);
+	}
 }