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54 lines
1.3 KiB
PHP
54 lines
1.3 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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public static function compute(array $actualLabels, array $predictedLabels, array $labels = []): array
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{
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$labels = count($labels) === 0 ? self::getUniqueLabels($actualLabels) : array_flip($labels);
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$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], $labels[$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];
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}
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return $matrix;
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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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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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return array_flip($labels);
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}
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}
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