These results are based on our legacy PHP analysis, consider migrating to our new PHP analysis engine instead. Learn more
1 | <?php |
||
2 | |||
3 | declare(strict_types=1); |
||
4 | |||
5 | namespace Phpml\Helper\Optimizer; |
||
6 | |||
7 | use Closure; |
||
8 | |||
9 | /** |
||
10 | * Batch version of Gradient Descent to optimize the weights |
||
11 | * of a classifier given samples, targets and the objective function to minimize |
||
12 | */ |
||
13 | class GD extends StochasticGD |
||
14 | { |
||
15 | /** |
||
16 | * Number of samples given |
||
17 | * |
||
18 | * @var int|null |
||
19 | */ |
||
20 | protected $sampleCount; |
||
21 | |||
22 | public function runOptimization(array $samples, array $targets, Closure $gradientCb): array |
||
23 | { |
||
24 | $this->samples = $samples; |
||
25 | $this->targets = $targets; |
||
26 | $this->gradientCb = $gradientCb; |
||
27 | $this->sampleCount = count($this->samples); |
||
28 | |||
29 | // Batch learning is executed: |
||
30 | $currIter = 0; |
||
31 | $this->costValues = []; |
||
32 | while ($this->maxIterations > $currIter++) { |
||
33 | $theta = $this->theta; |
||
34 | |||
35 | // Calculate update terms for each sample |
||
36 | [$errors, $updates, $totalPenalty] = $this->gradient($theta); |
||
0 ignored issues
–
show
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.
Loading history...
|
|||
37 | |||
38 | $this->updateWeightsWithUpdates($updates, $totalPenalty); |
||
39 | |||
40 | $this->costValues[] = array_sum($errors) / $this->sampleCount; |
||
41 | |||
42 | if ($this->earlyStop($theta)) { |
||
43 | break; |
||
44 | } |
||
45 | } |
||
46 | |||
47 | $this->clear(); |
||
48 | |||
49 | return $this->theta; |
||
50 | } |
||
51 | |||
52 | /** |
||
53 | * Calculates gradient, cost function and penalty term for each sample |
||
54 | * then returns them as an array of values |
||
55 | */ |
||
56 | protected function gradient(array $theta): array |
||
57 | { |
||
58 | $costs = []; |
||
59 | $gradient = []; |
||
60 | $totalPenalty = 0; |
||
61 | |||
62 | foreach ($this->samples as $index => $sample) { |
||
63 | $target = $this->targets[$index]; |
||
64 | |||
65 | $result = ($this->gradientCb)($theta, $sample, $target); |
||
66 | [$cost, $grad, $penalty] = array_pad($result, 3, 0); |
||
0 ignored issues
–
show
|
|||
67 | |||
68 | $costs[] = $cost; |
||
69 | $gradient[] = $grad; |
||
70 | $totalPenalty += $penalty; |
||
71 | } |
||
72 | |||
73 | $totalPenalty /= $this->sampleCount; |
||
74 | |||
75 | return [$costs, $gradient, $totalPenalty]; |
||
76 | } |
||
77 | |||
78 | protected function updateWeightsWithUpdates(array $updates, float $penalty): void |
||
79 | { |
||
80 | // Updates all weights at once |
||
81 | for ($i = 0; $i <= $this->dimensions; ++$i) { |
||
82 | if ($i === 0) { |
||
83 | $this->theta[0] -= $this->learningRate * array_sum($updates); |
||
84 | } else { |
||
85 | $col = array_column($this->samples, $i - 1); |
||
86 | |||
87 | $error = 0; |
||
88 | foreach ($col as $index => $val) { |
||
89 | $error += $val * $updates[$index]; |
||
90 | } |
||
91 | |||
92 | $this->theta[$i] -= $this->learningRate * |
||
93 | ($error + $penalty * $this->theta[$i]); |
||
94 | } |
||
95 | } |
||
96 | } |
||
97 | |||
98 | /** |
||
99 | * Clears the optimizer internal vars after the optimization process. |
||
100 | */ |
||
101 | protected function clear(): void |
||
102 | { |
||
103 | $this->sampleCount = null; |
||
104 | parent::clear(); |
||
105 | } |
||
106 | } |
||
107 |
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.