Configure an Activation Function per hidden layer (#208)

* ability to specify per-layer activation function

* some tests for new addition to layer

* appease style CI whitespace issue

* more flexible addition of layers, and developer can pass Layer object in manually

* new test for layer object in mlp constructor

* documentation for added MLP functionality
This commit is contained in:
Jonathan Baldie 2018-02-01 22:15:36 +00:00 committed by Arkadiusz Kondas
parent 8daed2484d
commit c32bf3fe2b
4 changed files with 98 additions and 3 deletions

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@ -19,6 +19,24 @@ $mlp = new MLPClassifier(4, [2], ['a', 'b', 'c']);
``` ```
An Activation Function may also be passed in with each individual hidden layer. Example:
```
use Phpml\NeuralNetwork\ActivationFunction\PReLU;
use Phpml\NeuralNetwork\ActivationFunction\Sigmoid;
$mlp = new MLPClassifier(4, [[2, new PReLU], [2, new Sigmoid]], ['a', 'b', 'c']);
```
Instead of configuring each hidden layer as an array, they may also be configured with Layer objects. Example:
```
use Phpml\NeuralNetwork\Layer;
use Phpml\NeuralNetwork\Node\Neuron;
$layer1 = new Layer(2, Neuron::class, new PReLU);
$layer2 = new Layer(2, Neuron::class, new Sigmoid);
$mlp = new MLPClassifier(4, [$layer1, $layer2], ['a', 'b', 'c']);
```
## Train ## Train
To train a MLP simply provide train samples and labels (as array). Example: To train a MLP simply provide train samples and labels (as array). Example:

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@ -142,10 +142,17 @@ abstract class MultilayerPerceptron extends LayeredNetwork implements Estimator,
$this->addLayer(new Layer($nodes, Input::class)); $this->addLayer(new Layer($nodes, Input::class));
} }
private function addNeuronLayers(array $layers, ?ActivationFunction $activationFunction = null): void private function addNeuronLayers(array $layers, ?ActivationFunction $defaultActivationFunction = null): void
{ {
foreach ($layers as $neurons) { foreach ($layers as $layer) {
$this->addLayer(new Layer($neurons, Neuron::class, $activationFunction)); if (is_array($layer)) {
$function = $layer[1] instanceof ActivationFunction ? $layer[1] : $defaultActivationFunction;
$this->addLayer(new Layer($layer[0], Neuron::class, $function));
} elseif ($layer instanceof Layer) {
$this->addLayer($layer);
} else {
$this->addLayer(new Layer($layer, Neuron::class, $defaultActivationFunction));
}
} }
} }

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@ -4,6 +4,7 @@ declare(strict_types=1);
namespace Phpml\Tests\NeuralNetwork\Network; namespace Phpml\Tests\NeuralNetwork\Network;
use Phpml\NeuralNetwork\ActivationFunction;
use Phpml\NeuralNetwork\Layer; use Phpml\NeuralNetwork\Layer;
use Phpml\NeuralNetwork\Network\LayeredNetwork; use Phpml\NeuralNetwork\Network\LayeredNetwork;
use Phpml\NeuralNetwork\Node\Input; use Phpml\NeuralNetwork\Node\Input;
@ -45,6 +46,15 @@ class LayeredNetworkTest extends TestCase
$this->assertEquals([0.5], $network->getOutput()); $this->assertEquals([0.5], $network->getOutput());
} }
public function testSetInputAndGetOutputWithCustomActivationFunctions(): void
{
$network = $this->getLayeredNetworkMock();
$network->addLayer(new Layer(2, Input::class, $this->getActivationFunctionMock()));
$network->setInput($input = [34, 43]);
$this->assertEquals($input, $network->getOutput());
}
/** /**
* @return LayeredNetwork|PHPUnit_Framework_MockObject_MockObject * @return LayeredNetwork|PHPUnit_Framework_MockObject_MockObject
*/ */
@ -52,4 +62,12 @@ class LayeredNetworkTest extends TestCase
{ {
return $this->getMockForAbstractClass(LayeredNetwork::class); return $this->getMockForAbstractClass(LayeredNetwork::class);
} }
/**
* @return ActivationFunction|PHPUnit_Framework_MockObject_MockObject
*/
private function getActivationFunctionMock()
{
return $this->getMockForAbstractClass(ActivationFunction::class);
}
} }

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@ -4,8 +4,12 @@ declare(strict_types=1);
namespace Phpml\Tests\NeuralNetwork\Network; namespace Phpml\Tests\NeuralNetwork\Network;
use Phpml\NeuralNetwork\ActivationFunction;
use Phpml\NeuralNetwork\Layer;
use Phpml\NeuralNetwork\Network\MultilayerPerceptron; use Phpml\NeuralNetwork\Network\MultilayerPerceptron;
use Phpml\NeuralNetwork\Node\Neuron;
use PHPUnit\Framework\TestCase; use PHPUnit\Framework\TestCase;
use PHPUnit_Framework_MockObject_MockObject;
class MultilayerPerceptronTest extends TestCase class MultilayerPerceptronTest extends TestCase
{ {
@ -26,4 +30,52 @@ class MultilayerPerceptronTest extends TestCase
$backprop = $this->readAttribute($mlp, 'backpropagation'); $backprop = $this->readAttribute($mlp, 'backpropagation');
$this->assertEquals(0.24, $this->readAttribute($backprop, 'learningRate')); $this->assertEquals(0.24, $this->readAttribute($backprop, 'learningRate'));
} }
public function testLearningRateSetterWithCustomActivationFunctions(): void
{
$activation_function = $this->getActivationFunctionMock();
/** @var MultilayerPerceptron $mlp */
$mlp = $this->getMockForAbstractClass(
MultilayerPerceptron::class,
[5, [[3, $activation_function], [5, $activation_function]], [0, 1], 1000, null, 0.42]
);
$this->assertEquals(0.42, $this->readAttribute($mlp, 'learningRate'));
$backprop = $this->readAttribute($mlp, 'backpropagation');
$this->assertEquals(0.42, $this->readAttribute($backprop, 'learningRate'));
$mlp->setLearningRate(0.24);
$this->assertEquals(0.24, $this->readAttribute($mlp, 'learningRate'));
$backprop = $this->readAttribute($mlp, 'backpropagation');
$this->assertEquals(0.24, $this->readAttribute($backprop, 'learningRate'));
}
public function testLearningRateSetterWithLayerObject(): void
{
$activation_function = $this->getActivationFunctionMock();
/** @var MultilayerPerceptron $mlp */
$mlp = $this->getMockForAbstractClass(
MultilayerPerceptron::class,
[5, [new Layer(3, Neuron::class, $activation_function), new Layer(5, Neuron::class, $activation_function)], [0, 1], 1000, null, 0.42]
);
$this->assertEquals(0.42, $this->readAttribute($mlp, 'learningRate'));
$backprop = $this->readAttribute($mlp, 'backpropagation');
$this->assertEquals(0.42, $this->readAttribute($backprop, 'learningRate'));
$mlp->setLearningRate(0.24);
$this->assertEquals(0.24, $this->readAttribute($mlp, 'learningRate'));
$backprop = $this->readAttribute($mlp, 'backpropagation');
$this->assertEquals(0.24, $this->readAttribute($backprop, 'learningRate'));
}
/**
* @return ActivationFunction|PHPUnit_Framework_MockObject_MockObject
*/
private function getActivationFunctionMock()
{
return $this->getMockForAbstractClass(ActivationFunction::class);
}
} }