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efrain |
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<?php
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declare(strict_types=1);
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namespace Phpml\Metric;
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use Phpml\Exception\InvalidArgumentException;
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use Phpml\Math\Statistic\Correlation;
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use Phpml\Math\Statistic\Mean;
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final class Regression
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{
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public static function meanSquaredError(array $targets, array $predictions): float
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{
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self::assertCountEquals($targets, $predictions);
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$errors = [];
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foreach ($targets as $index => $target) {
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$errors[] = (($target - $predictions[$index]) ** 2);
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}
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return Mean::arithmetic($errors);
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}
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public static function meanSquaredLogarithmicError(array $targets, array $predictions): float
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{
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self::assertCountEquals($targets, $predictions);
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$errors = [];
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foreach ($targets as $index => $target) {
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$errors[] = log((1 + $target) / (1 + $predictions[$index])) ** 2;
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}
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return Mean::arithmetic($errors);
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}
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public static function meanAbsoluteError(array $targets, array $predictions): float
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{
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self::assertCountEquals($targets, $predictions);
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$errors = [];
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foreach ($targets as $index => $target) {
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$errors[] = abs($target - $predictions[$index]);
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}
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return Mean::arithmetic($errors);
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}
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public static function medianAbsoluteError(array $targets, array $predictions): float
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{
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self::assertCountEquals($targets, $predictions);
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$errors = [];
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foreach ($targets as $index => $target) {
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$errors[] = abs($target - $predictions[$index]);
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}
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return (float) Mean::median($errors);
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}
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public static function r2Score(array $targets, array $predictions): float
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{
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self::assertCountEquals($targets, $predictions);
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return Correlation::pearson($targets, $predictions) ** 2;
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}
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public static function maxError(array $targets, array $predictions): float
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{
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self::assertCountEquals($targets, $predictions);
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$errors = [];
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foreach ($targets as $index => $target) {
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$errors[] = abs($target - $predictions[$index]);
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}
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return (float) max($errors);
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}
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private static function assertCountEquals(array &$targets, array &$predictions): void
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{
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if (count($targets) !== count($predictions)) {
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throw new InvalidArgumentException('Targets count must be equal with predictions count');
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}
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}
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}
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