Perceptron::__construct() - Code Metrics - Inspection of "Add .gitattributes" - php-ai/php-ml - Measure and Improve Code Quality continuously with Scrutinizer

Passed

Pull Request — master (#287)

by Marcin

created 2018-06-24 18:53 UTC

Perceptron::__construct() A

↳ Parent: Perceptron

Complexity

Conditions	5
Paths	4

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
dl	0
loc	17
rs	9.3888
c	0
b	0
f	0
cc	5
nc	4
nop	3

<?php

declare(strict_types=1);

namespace Phpml\Classification\Linear;

use Closure;
use Phpml\Classification\Classifier;
use Phpml\Exception\InvalidArgumentException;
use Phpml\Helper\OneVsRest;
use Phpml\Helper\Optimizer\GD;
use Phpml\Helper\Optimizer\Optimizer;
use Phpml\Helper\Optimizer\StochasticGD;
use Phpml\Helper\Predictable;
use Phpml\IncrementalEstimator;
use Phpml\Preprocessing\Normalizer;

class Perceptron implements Classifier, IncrementalEstimator
{
    use Predictable, OneVsRest;

    /**
     * @var Optimizer|GD|StochasticGD|null
     */
    protected $optimizer;

    /**
     * @var array
     */
    protected $labels = [];

    /**
     * @var int
     */
    protected $featureCount = 0;

    /**
     * @var array
     */
    protected $weights = [];

    /**
     * @var float
     */
    protected $learningRate;

    /**
     * @var int
     */
    protected $maxIterations;

    /**
     * @var Normalizer
     */
    protected $normalizer;

    /**
     * @var bool
     */
    protected $enableEarlyStop = true;

    /**
     * @var array
     */
    protected $costValues = [];

    /**
     * Initalize a perceptron classifier with given learning rate and maximum
     * number of iterations used while training the perceptron
     *
     * @param float $learningRate  Value between 0.0(exclusive) and 1.0(inclusive)
     * @param int   $maxIterations Must be at least 1
     *
     * @throws InvalidArgumentException
     */
    public function __construct(float $learningRate = 0.001, int $maxIterations = 1000, bool $normalizeInputs = true)
    {
        if ($learningRate <= 0.0 || $learningRate > 1.0) {
            throw new InvalidArgumentException('Learning rate should be a float value between 0.0(exclusive) and 1.0(inclusive)');
        }

        if ($maxIterations <= 0) {
            throw new InvalidArgumentException('Maximum number of iterations must be an integer greater than 0');
        }

        if ($normalizeInputs) {
            $this->normalizer = new Normalizer(Normalizer::NORM_STD);
        }

        $this->learningRate = $learningRate;
        $this->maxIterations = $maxIterations;
    }

    public function partialTrain(array $samples, array $targets, array $labels = []): void
    {
        $this->trainByLabel($samples, $targets, $labels);
    }

    public function trainBinary(array $samples, array $targets, array $labels): void
    {
        if ($this->normalizer !== null) {
            $this->normalizer->transform($samples);
        }

        // Set all target values to either -1 or 1
        $this->labels = [
            1 => $labels[0],
            -1 => $labels[1],
        ];
        foreach ($targets as $key => $target) {
            $targets[$key] = (string) $target == (string) $this->labels[1] ? 1 : -1;
        }

        // Set samples and feature count vars
        $this->featureCount = count($samples[0]);

        $this->runTraining($samples, $targets);
    }

    /**
     * Normally enabling early stopping for the optimization procedure may
     * help saving processing time while in some cases it may result in
     * premature convergence.<br>
     *
     * If "false" is given, the optimization procedure will always be executed
     * for $maxIterations times
     *
     * @return $this
     */
    public function setEarlyStop(bool $enable = true)
    {
        $this->enableEarlyStop = $enable;

        return $this;
    }

    /**
     * Returns the cost values obtained during the training.
     */
    public function getCostValues(): array
    {
        return $this->costValues;
    }

    protected function resetBinary(): void
    {
        $this->labels = [];
        $this->optimizer = null;
        $this->featureCount = 0;
        $this->weights = [];
        $this->costValues = [];
    }

    /**
     * Trains the perceptron model with Stochastic Gradient Descent optimization
     * to get the correct set of weights
     */
    protected function runTraining(array $samples, array $targets)
    {
        // The cost function is the sum of squares
        $callback = function ($weights, $sample, $target) {
            $this->weights = $weights;

            $prediction = $this->outputClass($sample);
            $gradient = $prediction - $target;
            $error = $gradient ** 2;

            return [$error, $gradient];
        };

        $this->runGradientDescent($samples, $targets, $callback);
    }

    /**
     * Executes a Gradient Descent algorithm for
     * the given cost function
     */
    protected function runGradientDescent(array $samples, array $targets, Closure $gradientFunc, bool $isBatch = false)
    {
        $class = $isBatch ? GD::class : StochasticGD::class;

        if ($this->optimizer === null) {
            $this->optimizer = (new $class($this->featureCount))
                ->setLearningRate($this->learningRate)
                ->setMaxIterations($this->maxIterations)
                ->setChangeThreshold(1e-6)
                ->setEarlyStop($this->enableEarlyStop);
        }

        $this->weights = $this->optimizer->runOptimization($samples, $targets, $gradientFunc);
        $this->costValues = $this->optimizer->getCostValues();
    }

    /**
     * Checks if the sample should be normalized and if so, returns the
     * normalized sample
     */
    protected function checkNormalizedSample(array $sample): array
    {
        if ($this->normalizer !== null) {
            $samples = [$sample];
            $this->normalizer->transform($samples);
            $sample = $samples[0];
        }

        return $sample;
    }

    /**
     * Calculates net output of the network as a float value for the given input
     *
     * @return int|float
     */
    protected function output(array $sample)
    {
        $sum = 0;
        foreach ($this->weights as $index => $w) {
            if ($index == 0) {
                $sum += $w;
            } else {
                $sum += $w * $sample[$index - 1];
            }
        }

        return $sum;
    }

    /**
     * Returns the class value (either -1 or 1) for the given input
     */
    protected function outputClass(array $sample): int
    {
        return $this->output($sample) > 0 ? 1 : -1;
    }

    /**
     * Returns the probability of the sample of belonging to the given label.
     *
     * The probability is simply taken as the distance of the sample
     * to the decision plane.
     *
     * @param mixed $label
     */
    protected function predictProbability(array $sample, $label): float
    {
        $predicted = $this->predictSampleBinary($sample);

        if ((string) $predicted == (string) $label) {
            $sample = $this->checkNormalizedSample($sample);

            return (float) abs($this->output($sample));
        }

        return 0.0;
    }

    /**
     * @return mixed
     */
    protected function predictSampleBinary(array $sample)
    {
        $sample = $this->checkNormalizedSample($sample);

        $predictedClass = $this->outputClass($sample);

        return $this->labels[$predictedClass];
    }
}


1			<?php
2
3			declare(strict_types=1);
4
5			namespace Phpml\Classification\Linear;
6
7			use Closure;
8			use Phpml\Classification\Classifier;
9			use Phpml\Exception\InvalidArgumentException;
10			use Phpml\Helper\OneVsRest;
11			use Phpml\Helper\Optimizer\GD;
12			use Phpml\Helper\Optimizer\Optimizer;
13			use Phpml\Helper\Optimizer\StochasticGD;
14			use Phpml\Helper\Predictable;
15			use Phpml\IncrementalEstimator;
16			use Phpml\Preprocessing\Normalizer;
17
18			class Perceptron implements Classifier, IncrementalEstimator
19			{
20			use Predictable, OneVsRest;
21
22			/**
23			* @var Optimizer\|GD\|StochasticGD\|null
24			*/
25			protected $optimizer;
26
27			/**
28			* @var array
29			*/
30			protected $labels = [];
31
32			/**
33			* @var int
34			*/
35			protected $featureCount = 0;
36
37			/**
38			* @var array
39			*/
40			protected $weights = [];
41
42			/**
43			* @var float
44			*/
45			protected $learningRate;
46
47			/**
48			* @var int
49			*/
50			protected $maxIterations;
51
52			/**
53			* @var Normalizer
54			*/
55			protected $normalizer;
56
57			/**
58			* @var bool
59			*/
60			protected $enableEarlyStop = true;
61
62			/**
63			* @var array
64			*/
65			protected $costValues = [];
66
67			/**
68			* Initalize a perceptron classifier with given learning rate and maximum
69			* number of iterations used while training the perceptron
70			*
71			* @param float $learningRate Value between 0.0(exclusive) and 1.0(inclusive)
72			* @param int $maxIterations Must be at least 1
73			*
74			* @throws InvalidArgumentException
75			*/
76			public function __construct(float $learningRate = 0.001, int $maxIterations = 1000, bool $normalizeInputs = true)
77			{
78			if ($learningRate <= 0.0 \|\| $learningRate > 1.0) {
79			throw new InvalidArgumentException('Learning rate should be a float value between 0.0(exclusive) and 1.0(inclusive)');
80			}
81
82			if ($maxIterations <= 0) {
83			throw new InvalidArgumentException('Maximum number of iterations must be an integer greater than 0');
84			}
85
86			if ($normalizeInputs) {
87			$this->normalizer = new Normalizer(Normalizer::NORM_STD);
88			}
89
90			$this->learningRate = $learningRate;
91			$this->maxIterations = $maxIterations;
92			}
93
94			public function partialTrain(array $samples, array $targets, array $labels = []): void
95			{
96			$this->trainByLabel($samples, $targets, $labels);
97			}
98
99			public function trainBinary(array $samples, array $targets, array $labels): void
100			{
101			if ($this->normalizer !== null) {
102			$this->normalizer->transform($samples);
103			}
104
105			// Set all target values to either -1 or 1
106			$this->labels = [
107			1 => $labels[0],
108			-1 => $labels[1],
109			];
110			foreach ($targets as $key => $target) {
111			$targets[$key] = (string) $target == (string) $this->labels[1] ? 1 : -1;
112			}
113
114			// Set samples and feature count vars
115			$this->featureCount = count($samples[0]);
116
117			$this->runTraining($samples, $targets);
118			}
119
120			/**
121			* Normally enabling early stopping for the optimization procedure may
122			* help saving processing time while in some cases it may result in
123			* premature convergence.<br>
124			*
125			* If "false" is given, the optimization procedure will always be executed
126			* for $maxIterations times
127			*
128			* @return $this
129			*/
130			public function setEarlyStop(bool $enable = true)
131			{
132			$this->enableEarlyStop = $enable;
133
134			return $this;
135			}
136
137			/**
138			* Returns the cost values obtained during the training.
139			*/
140			public function getCostValues(): array
141			{
142			return $this->costValues;
143			}
144
145			protected function resetBinary(): void
146			{
147			$this->labels = [];
148			$this->optimizer = null;
149			$this->featureCount = 0;
150			$this->weights = [];
151			$this->costValues = [];
152			}
153
154			/**
155			* Trains the perceptron model with Stochastic Gradient Descent optimization
156			* to get the correct set of weights
157			*/
158			protected function runTraining(array $samples, array $targets)
159			{
160			// The cost function is the sum of squares
161			$callback = function ($weights, $sample, $target) {
162			$this->weights = $weights;
163
164			$prediction = $this->outputClass($sample);
165			$gradient = $prediction - $target;
166			$error = $gradient ** 2;
167
168			return [$error, $gradient];
169			};
170
171			$this->runGradientDescent($samples, $targets, $callback);
172			}
173
174			/**
175			* Executes a Gradient Descent algorithm for
176			* the given cost function
177			*/
178			protected function runGradientDescent(array $samples, array $targets, Closure $gradientFunc, bool $isBatch = false)
179			{
180			$class = $isBatch ? GD::class : StochasticGD::class;
181
182			if ($this->optimizer === null) {
183			$this->optimizer = (new $class($this->featureCount))
184			->setLearningRate($this->learningRate)
185			->setMaxIterations($this->maxIterations)
186			->setChangeThreshold(1e-6)
187			->setEarlyStop($this->enableEarlyStop);
188			}
189
190			$this->weights = $this->optimizer->runOptimization($samples, $targets, $gradientFunc);
191			$this->costValues = $this->optimizer->getCostValues();
192			}
193
194			/**
195			* Checks if the sample should be normalized and if so, returns the
196			* normalized sample
197			*/
198			protected function checkNormalizedSample(array $sample): array
199			{
200			if ($this->normalizer !== null) {
201			$samples = [$sample];
202			$this->normalizer->transform($samples);
203			$sample = $samples[0];
204			}
205
206			return $sample;
207			}
208
209			/**
210			* Calculates net output of the network as a float value for the given input
211			*
212			* @return int\|float
213			*/
214			protected function output(array $sample)
215			{
216			$sum = 0;
217			foreach ($this->weights as $index => $w) {
218			if ($index == 0) {
219			$sum += $w;
220			} else {
221			$sum += $w * $sample[$index - 1];
222			}
223			}
224
225			return $sum;
226			}
227
228			/**
229			* Returns the class value (either -1 or 1) for the given input
230			*/
231			protected function outputClass(array $sample): int
232			{
233			return $this->output($sample) > 0 ? 1 : -1;
234			}
235
236			/**
237			* Returns the probability of the sample of belonging to the given label.
238			*
239			* The probability is simply taken as the distance of the sample
240			* to the decision plane.
241			*
242			* @param mixed $label
243			*/
244			protected function predictProbability(array $sample, $label): float
245			{
246			$predicted = $this->predictSampleBinary($sample);
247
248			if ((string) $predicted == (string) $label) {
249			$sample = $this->checkNormalizedSample($sample);
250
251			return (float) abs($this->output($sample));
252			}
253
254			return 0.0;
255			}
256
257			/**
258			* @return mixed
259			*/
260			protected function predictSampleBinary(array $sample)
261			{
262			$sample = $this->checkNormalizedSample($sample);
263
264			$predictedClass = $this->outputClass($sample);
265
266			return $this->labels[$predictedClass];
267			}
268			}
269

php-ai / php-ml

Pull Request — master (#287)

Perceptron::__construct() A

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