Fix static analysis errors from phpstan upgrade to 0.12 (#426)

phpstan.neon

@@ -4,12 +4,18 @@ includes:
     - vendor/phpstan/phpstan-phpunit/rules.neon
 
 parameters:
+    checkGenericClassInNonGenericObjectType: false
+    checkMissingIterableValueType: false
+
     ignoreErrors:
         - '#Property Phpml\\Clustering\\KMeans\\Cluster\:\:\$points \(iterable\<Phpml\\Clustering\\KMeans\\Point\>\&SplObjectStorage\) does not accept SplObjectStorage#'
         - '#Phpml\\Dataset\\(.*)Dataset::__construct\(\) does not call parent constructor from Phpml\\Dataset\\ArrayDataset#'
         - '#Variable property access on .+#'
         - '#Variable method call on .+#'
-
+        - message: '#ReflectionClass#'
+          paths:
+            - src/Classification/Ensemble/AdaBoost.php
+            - src/Classification/Ensemble/Bagging.php
         # probably known value
         - '#Method Phpml\\Classification\\DecisionTree::getBestSplit\(\) should return Phpml\\Classification\\DecisionTree\\DecisionTreeLeaf but returns Phpml\\Classification\\DecisionTree\\DecisionTreeLeaf\|null#'
         - '#Call to an undefined method Phpml\\Helper\\Optimizer\\Optimizer::getCostValues\(\)#'

src/Association/Apriori.php

@@ -104,11 +104,11 @@ class Apriori implements Associator
      */
     protected function predictSample(array $sample): array
     {
-        $predicts = array_values(array_filter($this->getRules(), function ($rule) use ($sample) {
+        $predicts = array_values(array_filter($this->getRules(), function ($rule) use ($sample): bool {
             return $this->equals($rule[self::ARRAY_KEY_ANTECEDENT], $sample);
         }));
 
-        return array_map(function ($rule) {
+        return array_map(static function ($rule) {
             return $rule[self::ARRAY_KEY_CONSEQUENT];
         }, $predicts);
     }
@@ -177,7 +177,7 @@ class Apriori implements Associator
         $cardinality = count($sample);
         $antecedents = $this->powerSet($sample);
 
-        return array_filter($antecedents, function ($antecedent) use ($cardinality) {
+        return array_filter($antecedents, static function ($antecedent) use ($cardinality): bool {
             return (count($antecedent) != $cardinality) && ($antecedent != []);
         });
     }
@@ -199,7 +199,7 @@ class Apriori implements Associator
             }
         }
 
-        return array_map(function ($entry) {
+        return array_map(static function ($entry): array {
             return [$entry];
         }, $items);
     }
@@ -213,7 +213,7 @@ class Apriori implements Associator
      */
     private function frequent(array $samples): array
     {
-        return array_values(array_filter($samples, function ($entry) {
+        return array_values(array_filter($samples, function ($entry): bool {
             return $this->support($entry) >= $this->support;
         }));
     }
@@ -288,7 +288,7 @@ class Apriori implements Associator
      */
     private function frequency(array $sample): int
     {
-        return count(array_filter($this->samples, function ($entry) use ($sample) {
+        return count(array_filter($this->samples, function ($entry) use ($sample): bool {
             return $this->subset($entry, $sample);
         }));
     }
@@ -303,7 +303,7 @@ class Apriori implements Associator
      */
     private function contains(array $system, array $set): bool
     {
-        return (bool) array_filter($system, function ($entry) use ($set) {
+        return (bool) array_filter($system, function ($entry) use ($set): bool {
             return $this->equals($entry, $set);
         });
     }

src/Classification/Linear/Adaline.php

@@ -58,7 +58,7 @@ class Adaline extends Perceptron
     protected function runTraining(array $samples, array $targets): void
     {
         // The cost function is the sum of squares
-        $callback = function ($weights, $sample, $target) {
+        $callback = function ($weights, $sample, $target): array {
             $this->weights = $weights;
 
             $output = $this->output($sample);

src/Classification/Linear/LogisticRegression.php

@@ -188,7 +188,7 @@ class LogisticRegression extends Adaline
                  * The gradient of the cost function to be used with gradient descent:
                  *		∇J(x) = -(y - h(x)) = (h(x) - y)
                  */
-                return function ($weights, $sample, $y) use ($penalty) {
+                return function ($weights, $sample, $y) use ($penalty): array {
                     $this->weights = $weights;
                     $hX = $this->output($sample);
 
@@ -220,7 +220,7 @@ class LogisticRegression extends Adaline
                  * The gradient of the cost function:
                  *		∇J(x) = -(h(x) - y) . h(x) . (1 - h(x))
                  */
-                return function ($weights, $sample, $y) use ($penalty) {
+                return function ($weights, $sample, $y) use ($penalty): array {
                     $this->weights = $weights;
                     $hX = $this->output($sample);
 

src/Classification/Linear/Perceptron.php

@@ -154,7 +154,7 @@ class Perceptron implements Classifier, IncrementalEstimator
     protected function runTraining(array $samples, array $targets): void
     {
         // The cost function is the sum of squares
-        $callback = function ($weights, $sample, $target) {
+        $callback = function ($weights, $sample, $target): array {
             $this->weights = $weights;
 
             $prediction = $this->outputClass($sample);

src/Clustering/FuzzyCMeans.php

@@ -139,7 +139,7 @@ class FuzzyCMeans implements Clusterer
                 $total += $val;
             }
 
-            $this->membership[] = array_map(function ($val) use ($total) {
+            $this->membership[] = array_map(static function ($val) use ($total): float {
                 return $val / $total;
             }, $row);
         }

src/Clustering/KMeans/Space.php

@@ -88,7 +88,7 @@ class Space extends SplObjectStorage
         $min = $this->newPoint(array_fill(0, $this->dimension, null));
         $max = $this->newPoint(array_fill(0, $this->dimension, null));
 
-        /** @var self $point */
+        /** @var Point $point */
         foreach ($this as $point) {
             for ($n = 0; $n < $this->dimension; ++$n) {
                 if ($min[$n] === null || $min[$n] > $point[$n]) {

src/Dataset/CsvDataset.php

@@ -35,8 +35,8 @@ class CsvDataset extends ArrayDataset
         }
 
         $samples = $targets = [];
-        while (($data = fgetcsv($handle, $maxLineLength, $delimiter)) !== false) {
+        while ($data = fgetcsv($handle, $maxLineLength, $delimiter)) {
-            $samples[] = array_slice((array) $data, 0, $features);
+            $samples[] = array_slice($data, 0, $features);
             $targets[] = $data[$features];
         }
 

src/DimensionReduction/KernelPCA.php

@@ -179,13 +179,13 @@ class KernelPCA extends PCA
                 // k(x,y)=exp(-γ.|x-y|) where |..| is Euclidean distance
                 $dist = new Euclidean();
 
-                return function ($x, $y) use ($dist) {
+                return function ($x, $y) use ($dist): float {
                     return exp(-$this->gamma * $dist->sqDistance($x, $y));
                 };
 
             case self::KERNEL_SIGMOID:
                 // k(x,y)=tanh(γ.xT.y+c0) where c0=1
-                return function ($x, $y) {
+                return function ($x, $y): float {
                     $res = Matrix::dot($x, $y)[0] + 1.0;
 
                     return tanh((float) $this->gamma * $res);
@@ -195,7 +195,7 @@ class KernelPCA extends PCA
                 // k(x,y)=exp(-γ.|x-y|) where |..| is Manhattan distance
                 $dist = new Manhattan();
 
-                return function ($x, $y) use ($dist) {
+                return function ($x, $y) use ($dist): float {
                     return exp(-$this->gamma * $dist->distance($x, $y));
                 };
 

src/FeatureSelection/VarianceThreshold.php

@@ -37,7 +37,7 @@ final class VarianceThreshold implements Transformer
 
     public function fit(array $samples, ?array $targets = null): void
     {
-        $this->variances = array_map(function (array $column) {
+        $this->variances = array_map(static function (array $column): float {
             return Variance::population($column);
         }, Matrix::transposeArray($samples));
 

src/Helper/Optimizer/GD.php

@@ -38,7 +38,7 @@ class GD extends StochasticGD
 
             $this->updateWeightsWithUpdates($updates, $totalPenalty);
 
-            $this->costValues[] = array_sum($errors) / $this->sampleCount;
+            $this->costValues[] = array_sum($errors) / (int) $this->sampleCount;
 
             if ($this->earlyStop($theta)) {
                 break;

src/Math/Matrix.php

@@ -126,7 +126,7 @@ class Matrix
     public function transpose(): self
     {
         if ($this->rows === 1) {
-            $matrix = array_map(function ($el) {
+            $matrix = array_map(static function ($el): array {
                 return [$el];
             }, $this->matrix[0]);
         } else {

src/Math/Statistic/ANOVA.php

@@ -28,7 +28,7 @@ final class ANOVA
             throw new InvalidArgumentException('The array must have at least 2 elements');
         }
 
-        $samplesPerClass = array_map(function (array $class): int {
+        $samplesPerClass = array_map(static function (array $class): int {
             return count($class);
         }, $samples);
         $allSamples = (int) array_sum($samplesPerClass);
@@ -41,10 +41,10 @@ final class ANOVA
         $dfbn = $classes - 1;
         $dfwn = $allSamples - $classes;
 
-        $msb = array_map(function ($s) use ($dfbn) {
+        $msb = array_map(static function ($s) use ($dfbn) {
             return $s / $dfbn;
         }, $ssbn);
-        $msw = array_map(function ($s) use ($dfwn) {
+        $msw = array_map(static function ($s) use ($dfwn) {
             if ($dfwn === 0) {
                 return 1;
             }
@@ -76,7 +76,7 @@ final class ANOVA
 
     private static function sumOfFeaturesPerClass(array $samples): array
     {
-        return array_map(function (array $class) {
+        return array_map(static function (array $class): array {
             $sum = array_fill(0, count($class[0]), 0);
             foreach ($class as $sample) {
                 foreach ($sample as $index => $feature) {
@@ -97,7 +97,7 @@ final class ANOVA
             }
         }
 
-        return array_map(function ($sum) {
+        return array_map(static function ($sum) {
             return $sum ** 2;
         }, $squares);
     }

src/Math/Statistic/StandardDeviation.php

@@ -50,7 +50,7 @@ class StandardDeviation
         $mean = Mean::arithmetic($numbers);
 
         return array_sum(array_map(
-            function ($val) use ($mean) {
+            static function ($val) use ($mean): float {
                 return ($val - $mean) ** 2;
             },
             $numbers

src/Metric/ClassificationReport.php

@@ -148,7 +148,7 @@ class ClassificationReport
 
         $precision = $this->computePrecision($truePositive, $falsePositive);
         $recall = $this->computeRecall($truePositive, $falseNegative);
-        $f1score = $this->computeF1Score((float) $precision, (float) $recall);
+        $f1score = $this->computeF1Score($precision, $recall);
 
         $this->average = compact('precision', 'recall', 'f1score');
     }
@@ -186,10 +186,7 @@ class ClassificationReport
         }
     }
 
-    /**
+    private function computePrecision(int $truePositive, int $falsePositive): float
-     * @return float|string
-     */
-    private function computePrecision(int $truePositive, int $falsePositive)
     {
         $divider = $truePositive + $falsePositive;
         if ($divider == 0) {
@@ -199,10 +196,7 @@ class ClassificationReport
         return $truePositive / $divider;
     }
 
-    /**
+    private function computeRecall(int $truePositive, int $falseNegative): float
-     * @return float|string
-     */
-    private function computeRecall(int $truePositive, int $falseNegative)
     {
         $divider = $truePositive + $falseNegative;
         if ($divider == 0) {

src/NeuralNetwork/Node/Neuron.php

@@ -33,7 +33,7 @@ class Neuron implements Node
 
     public function __construct(?ActivationFunction $activationFunction = null)
     {
-        $this->activationFunction = $activationFunction ?: new Sigmoid();
+        $this->activationFunction = $activationFunction ?? new Sigmoid();
     }
 
     public function addSynapse(Synapse $synapse): void

src/NeuralNetwork/Node/Neuron/Synapse.php

@@ -24,7 +24,7 @@ class Synapse
     public function __construct(Node $node, ?float $weight = null)
     {
         $this->node = $node;
-        $this->weight = $weight ?: $this->generateRandomWeight();
+        $this->weight = $weight ?? $this->generateRandomWeight();
     }
 
     public function getOutput(): float

src/Pipeline.php

@@ -61,12 +61,12 @@ class Pipeline implements Estimator, Transformer
      */
     public function predict(array $samples)
     {
+        $this->transform($samples);
+
         if ($this->estimator === null) {
             throw new InvalidOperationException('Pipeline without estimator can\'t use predict method');
         }
 
-        $this->transform($samples);
-
         return $this->estimator->predict($samples);
     }
 

src/Regression/DecisionTreeRegressor.php

@@ -121,7 +121,7 @@ final class DecisionTreeRegressor extends CART implements Regression
 
     protected function splitImpurity(array $groups): float
     {
-        $samplesCount = (int) array_sum(array_map(static function (array $group) {
+        $samplesCount = (int) array_sum(array_map(static function (array $group): int {
             return count($group[0]);
         }, $groups));
 

src/Tree/Node/DecisionNode.php

@@ -50,7 +50,7 @@ class DecisionNode extends BinaryNode implements PurityNode
         $this->value = $value;
         $this->groups = $groups;
         $this->impurity = $impurity;
-        $this->samplesCount = (int) array_sum(array_map(function (array $group) {
+        $this->samplesCount = (int) array_sum(array_map(static function (array $group): int {
             return count($group[0]);
         }, $groups));
     }

tests/DimensionReduction/KernelPCATest.php

@@ -40,7 +40,7 @@ class KernelPCATest extends TestCase
         // during the calculation of eigenValues, we have to compare
         // absolute value of the values
         array_map(function ($val1, $val2) use ($epsilon): void {
-            self::assertEqualsWithDelta(abs($val1), abs($val2), $epsilon);
+            self::assertEqualsWithDelta(abs($val1[0]), abs($val2[0]), $epsilon);
         }, $transformed, $reducedData);
 
         // Fitted KernelPCA object can also transform an arbitrary sample of the

tests/DimensionReduction/PCATest.php

@@ -42,7 +42,7 @@ class PCATest extends TestCase
         // during the calculation of eigenValues, we have to compare
         // absolute value of the values
         array_map(function ($val1, $val2) use ($epsilon): void {
-            self::assertEqualsWithDelta(abs($val1), abs($val2), $epsilon);
+            self::assertEqualsWithDelta(abs($val1[0]), abs($val2[0]), $epsilon);
         }, $transformed, $reducedData);
 
         // Test fitted PCA object to transform an arbitrary sample of the
@@ -52,7 +52,7 @@ class PCATest extends TestCase
             $newRow2 = $pca->transform($row);
 
             array_map(function ($val1, $val2) use ($epsilon): void {
-                self::assertEqualsWithDelta(abs($val1), abs($val2), $epsilon);
+                self::assertEqualsWithDelta(abs($val1[0][0]), abs($val2[0]), $epsilon);
             }, $newRow, $newRow2);
         }
     }

tests/Helper/Optimizer/ConjugateGradientTest.php

@@ -21,7 +21,7 @@ class ConjugateGradientTest extends TestCase
             $targets[] = -1 + 2 * $x;
         }
 
-        $callback = function ($theta, $sample, $target) {
+        $callback = static function ($theta, $sample, $target): array {
             $y = $theta[0] + $theta[1] * $sample[0];
             $cost = (($y - $target) ** 2) / 2;
             $grad = $y - $target;
@@ -47,7 +47,7 @@ class ConjugateGradientTest extends TestCase
             $targets[] = -1 + 2 * $x;
         }
 
-        $callback = function ($theta, $sample, $target) {
+        $callback = static function ($theta, $sample, $target): array {
             $y = $theta[0] + $theta[1] * $sample[0];
             $cost = (($y - $target) ** 2) / 2;
             $grad = $y - $target;
@@ -76,7 +76,7 @@ class ConjugateGradientTest extends TestCase
             $targets[] = -1 + 2 * $x0 - 3 * $x1;
         }
 
-        $callback = function ($theta, $sample, $target) {
+        $callback = static function ($theta, $sample, $target): array {
             $y = $theta[0] + $theta[1] * $sample[0] + $theta[2] * $sample[1];
             $cost = (($y - $target) ** 2) / 2;
             $grad = $y - $target;

tests/Helper/Optimizer/GDTest.php

@@ -20,7 +20,7 @@ class GDTest extends TestCase
             $targets[] = -1 + 2 * $x;
         }
 
-        $callback = function ($theta, $sample, $target) {
+        $callback = static function ($theta, $sample, $target): array {
             $y = $theta[0] + $theta[1] * $sample[0];
             $cost = (($y - $target) ** 2) / 2;
             $grad = $y - $target;
@@ -47,7 +47,7 @@ class GDTest extends TestCase
             $targets[] = -1 + 2 * $x0 - 3 * $x1;
         }
 
-        $callback = function ($theta, $sample, $target) {
+        $callback = static function ($theta, $sample, $target): array {
             $y = $theta[0] + $theta[1] * $sample[0] + $theta[2] * $sample[1];
             $cost = (($y - $target) ** 2) / 2;
             $grad = $y - $target;

tests/Helper/Optimizer/StochasticGDTest.php

@@ -20,7 +20,7 @@ class StochasticGDTest extends TestCase
             $targets[] = -1 + 2 * $x;
         }
 
-        $callback = function ($theta, $sample, $target) {
+        $callback = static function ($theta, $sample, $target): array {
             $y = $theta[0] + $theta[1] * $sample[0];
             $cost = (($y - $target) ** 2) / 2;
             $grad = $y - $target;
@@ -47,7 +47,7 @@ class StochasticGDTest extends TestCase
             $targets[] = -1 + 2 * $x0 - 3 * $x1;
         }
 
-        $callback = function ($theta, $sample, $target) {
+        $callback = static function ($theta, $sample, $target): array {
             $y = $theta[0] + $theta[1] * $sample[0] + $theta[2] * $sample[1];
             $cost = (($y - $target) ** 2) / 2;
             $grad = $y - $target;

tests/Preprocessing/NormalizerTest.php

@@ -126,7 +126,7 @@ class NormalizerTest extends TestCase
         foreach ($samples as $sample) {
             $errors = array_filter(
                 $sample,
-                function ($element) {
+                function ($element): bool {
                     return $element < -3 || $element > 3;
                 }
             );