50 lines
1.3 KiB
PHP
50 lines
1.3 KiB
PHP
<?php
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declare(strict_types=1);
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namespace Phpml\CrossValidation;
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use Phpml\Dataset\ArrayDataset;
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use Phpml\Dataset\Dataset;
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class StratifiedRandomSplit extends RandomSplit
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{
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protected function splitDataset(Dataset $dataset, float $testSize): void
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{
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$datasets = $this->splitByTarget($dataset);
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foreach ($datasets as $targetSet) {
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parent::splitDataset($targetSet, $testSize);
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}
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}
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/**
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* @return Dataset[]
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*/
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private function splitByTarget(Dataset $dataset): array
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{
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$targets = $dataset->getTargets();
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$samples = $dataset->getSamples();
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$uniqueTargets = array_unique($targets);
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/** @var array $split */
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$split = array_combine($uniqueTargets, array_fill(0, count($uniqueTargets), []));
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foreach ($samples as $key => $sample) {
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$split[$targets[$key]][] = $sample;
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}
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return $this->createDatasets($uniqueTargets, $split);
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}
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private function createDatasets(array $uniqueTargets, array $split): array
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{
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$datasets = [];
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foreach ($uniqueTargets as $target) {
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$datasets[$target] = new ArrayDataset($split[$target], array_fill(0, count($split[$target]), $target));
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}
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return $datasets;
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}
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}
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