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<?php |
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declare(strict_types=1); |
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namespace Phpml\NeuralNetwork\Network; |
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use Phpml\Exception\InvalidArgumentException; |
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use Phpml\NeuralNetwork\ActivationFunction; |
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use Phpml\NeuralNetwork\Layer; |
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use Phpml\NeuralNetwork\Node\Bias; |
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use Phpml\NeuralNetwork\Node\Input; |
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use Phpml\NeuralNetwork\Node\Neuron; |
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use Phpml\NeuralNetwork\Node\Neuron\Synapse; |
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use Phpml\Helper\Predictable; |
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class MultilayerPerceptron extends LayeredNetwork |
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{ |
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use Predictable; |
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/** |
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* @var array |
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*/ |
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private $classes = []; |
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/** |
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* @param int $inputLayerFeatures |
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* @param array $hiddenLayers |
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* @param array $classes |
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* @param ActivationFunction|null $activationFunction |
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* |
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* @throws InvalidArgumentException |
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*/ |
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public function __construct(int $inputLayerFeatures, array $hiddenLayers, array $classes, ActivationFunction $activationFunction = null) |
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{ |
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if (count($inputLayerFeatures) < 1) { |
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throw InvalidArgumentException::invalidLayersNumber(); |
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} |
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$nClasses = count($classes); |
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if ($nClasses < 2) { |
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throw InvalidArgumentException::invalidClassesNumber(); |
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} |
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$this->classes = $classes; |
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$this->addInputLayer($inputLayerFeatures); |
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$this->addNeuronLayers($hiddenLayers, $activationFunction); |
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$this->addNeuronLayers([$nClasses], $activationFunction); |
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$this->addBiasNodes(); |
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$this->generateSynapses(); |
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} |
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/** |
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* @param mixed $target |
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* @return int |
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*/ |
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public function getTargetClass($target): int |
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{ |
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if (in_array($target, $this->classes) === false) { |
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throw InvalidArgumentException::invalidTarget($target); |
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} |
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return array_search($target, $this->classes); |
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} |
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/** |
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* @param array $sample |
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* |
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* @return mixed |
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*/ |
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public function predictSample(array $sample) |
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{ |
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$output = $this->setInput($sample)->getOutput(); |
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$predictedClass = null; |
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$max = 0; |
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foreach ($output as $class => $value) { |
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if ($value > $max) { |
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$predictedClass = $class; |
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$max = $value; |
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} |
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} |
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return $this->classes[$predictedClass]; |
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} |
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/** |
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* @param int $nodes |
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*/ |
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private function addInputLayer(int $nodes) |
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{ |
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$this->addLayer(new Layer($nodes, Input::class)); |
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} |
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/** |
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* @param array $layers |
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* @param ActivationFunction|null $activationFunction |
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*/ |
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private function addNeuronLayers(array $layers, ActivationFunction $activationFunction = null) |
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{ |
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foreach ($layers as $neurons) { |
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$this->addLayer(new Layer($neurons, Neuron::class, $activationFunction)); |
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} |
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} |
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private function generateSynapses() |
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{ |
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$layersNumber = count($this->layers) - 1; |
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for ($i = 0; $i < $layersNumber; ++$i) { |
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$currentLayer = $this->layers[$i]; |
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$nextLayer = $this->layers[$i + 1]; |
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$this->generateLayerSynapses($nextLayer, $currentLayer); |
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} |
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} |
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private function addBiasNodes() |
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{ |
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$biasLayers = count($this->layers) - 1; |
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for ($i = 0; $i < $biasLayers; ++$i) { |
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$this->layers[$i]->addNode(new Bias()); |
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} |
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} |
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/** |
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* @param Layer $nextLayer |
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* @param Layer $currentLayer |
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*/ |
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private function generateLayerSynapses(Layer $nextLayer, Layer $currentLayer) |
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{ |
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foreach ($nextLayer->getNodes() as $nextNeuron) { |
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if ($nextNeuron instanceof Neuron) { |
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$this->generateNeuronSynapses($currentLayer, $nextNeuron); |
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} |
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} |
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} |
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/** |
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* @param Layer $currentLayer |
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* @param Neuron $nextNeuron |
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*/ |
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private function generateNeuronSynapses(Layer $currentLayer, Neuron $nextNeuron) |
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{ |
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foreach ($currentLayer->getNodes() as $currentNeuron) { |
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$nextNeuron->addSynapse(new Synapse($currentNeuron)); |
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} |
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} |
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} |
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php-ai /
php-ml
