Passed
Push — master ( e83f7b...d953ef )
by Arkadiusz
03:28
created

GD::clear()   A

Complexity

Conditions 1
Paths 1

Size

Total Lines 5
Code Lines 3

Duplication

Lines 0
Ratio 0 %

Importance

Changes 0
Metric Value
dl 0
loc 5
rs 9.4285
c 0
b 0
f 0
cc 1
eloc 3
nc 1
nop 0
1
<?php
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declare(strict_types=1);
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namespace Phpml\Helper\Optimizer;
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use Closure;
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/**
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 * Batch version of Gradient Descent to optimize the weights
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 * of a classifier given samples, targets and the objective function to minimize
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 */
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class GD extends StochasticGD
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{
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    /**
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     * Number of samples given
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     *
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     * @var int|null
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     */
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    protected $sampleCount;
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    public function runOptimization(array $samples, array $targets, Closure $gradientCb): array
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    {
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        $this->samples = $samples;
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        $this->targets = $targets;
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        $this->gradientCb = $gradientCb;
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        $this->sampleCount = count($this->samples);
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        // Batch learning is executed:
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        $currIter = 0;
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        $this->costValues = [];
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        while ($this->maxIterations > $currIter++) {
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            $theta = $this->theta;
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            // Calculate update terms for each sample
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            [$errors, $updates, $totalPenalty] = $this->gradient($theta);
0 ignored issues
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Bug introduced by TomasVotruba
The variable $errors does not exist. Did you forget to declare it?

This check marks access to variables or properties that have not been declared yet. While PHP has no explicit notion of declaring a variable, accessing it before a value is assigned to it is most likely a bug.

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Bug introduced by TomasVotruba
The variable $updates does not exist. Did you forget to declare it?

This check marks access to variables or properties that have not been declared yet. While PHP has no explicit notion of declaring a variable, accessing it before a value is assigned to it is most likely a bug.

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Bug introduced by TomasVotruba
The variable $totalPenalty does not exist. Did you forget to declare it?

This check marks access to variables or properties that have not been declared yet. While PHP has no explicit notion of declaring a variable, accessing it before a value is assigned to it is most likely a bug.

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            $this->updateWeightsWithUpdates($updates, $totalPenalty);
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            $this->costValues[] = array_sum($errors) / $this->sampleCount;
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            if ($this->earlyStop($theta)) {
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                break;
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            }
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        }
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        $this->clear();
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        return $this->theta;
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    }
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    /**
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     * Calculates gradient, cost function and penalty term for each sample
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     * then returns them as an array of values
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     */
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    protected function gradient(array $theta): array
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    {
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        $costs = [];
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        $gradient = [];
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        $totalPenalty = 0;
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        foreach ($this->samples as $index => $sample) {
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            $target = $this->targets[$index];
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            $result = ($this->gradientCb)($theta, $sample, $target);
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            [$cost, $grad, $penalty] = array_pad($result, 3, 0);
0 ignored issues
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Bug introduced by TomasVotruba
The variable $cost does not exist. Did you forget to declare it?

This check marks access to variables or properties that have not been declared yet. While PHP has no explicit notion of declaring a variable, accessing it before a value is assigned to it is most likely a bug.

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Bug introduced by TomasVotruba
The variable $grad does not exist. Did you forget to declare it?

This check marks access to variables or properties that have not been declared yet. While PHP has no explicit notion of declaring a variable, accessing it before a value is assigned to it is most likely a bug.

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Bug introduced by TomasVotruba
The variable $penalty does not exist. Did you mean $totalPenalty?

This check looks for variables that are accessed but have not been defined. It raises an issue if it finds another variable that has a similar name.

The variable may have been renamed without also renaming all references.

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            $costs[] = $cost;
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            $gradient[] = $grad;
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            $totalPenalty += $penalty;
0 ignored issues
show
Bug introduced by Mustafa Karabulut
The variable $penalty does not exist. Did you mean $totalPenalty?

This check looks for variables that are accessed but have not been defined. It raises an issue if it finds another variable that has a similar name.

The variable may have been renamed without also renaming all references.

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        }
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        $totalPenalty /= $this->sampleCount;
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        return [$costs, $gradient, $totalPenalty];
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    }
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    protected function updateWeightsWithUpdates(array $updates, float $penalty): void
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    {
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        // Updates all weights at once
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        for ($i = 0; $i <= $this->dimensions; ++$i) {
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            if ($i === 0) {
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                $this->theta[0] -= $this->learningRate * array_sum($updates);
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            } else {
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                $col = array_column($this->samples, $i - 1);
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                $error = 0;
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                foreach ($col as $index => $val) {
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                    $error += $val * $updates[$index];
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                }
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                $this->theta[$i] -= $this->learningRate *
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                    ($error + $penalty * $this->theta[$i]);
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            }
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        }
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    }
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    /**
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     * Clears the optimizer internal vars after the optimization process.
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     */
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    protected function clear(): void
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    {
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        $this->sampleCount = null;
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        parent::clear();
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    }
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}
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