72 lines
1.6 KiB
PHP
72 lines
1.6 KiB
PHP
<?php
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declare(strict_types=1);
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namespace Phpml\Metric;
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class ConfusionMatrix
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{
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/**
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* @param array $actualLabels
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* @param array $predictedLabels
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* @param array $labels
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*
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* @return array
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*/
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public static function compute(array $actualLabels, array $predictedLabels, array $labels = null): array
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{
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$labels = $labels ? array_flip($labels) : self::getUniqueLabels($actualLabels);
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$matrix = self::generateMatrixWithZeros($labels);
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foreach ($actualLabels as $index => $actual) {
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$predicted = $predictedLabels[$index];
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if (!isset($labels[$actual]) || !isset($labels[$predicted])) {
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continue;
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}
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if ($predicted === $actual) {
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$row = $column = $labels[$actual];
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} else {
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$row = $labels[$actual];
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$column = $labels[$predicted];
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}
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$matrix[$row][$column] += 1;
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}
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return $matrix;
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}
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/**
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* @param array $labels
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*
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* @return array
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*/
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private static function generateMatrixWithZeros(array $labels): array
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{
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$count = count($labels);
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$matrix = [];
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for ($i = 0; $i < $count; ++$i) {
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$matrix[$i] = array_fill(0, $count, 0);
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}
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return $matrix;
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}
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/**
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* @param array $labels
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*
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* @return array
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*/
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private static function getUniqueLabels(array $labels): array
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{
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$labels = array_values(array_unique($labels));
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sort($labels);
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$labels = array_flip($labels);
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return $labels;
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}
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}
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