[coding standard] fix imports order and drop unused docs typehints (#145)

* fix imports order

* drop unused docs typehints, make use of return types where possible

docs/math/distance.md

@@ -94,7 +94,7 @@ class CustomDistance implements Distance
      *
      * @return float
      */
-    public function distance(array $a, array $b): float
+    public function distance(array $a, array $b) : float
     {
         $distance = [];
         $count = count($a);

src/Phpml/Association/Apriori.php

@@ -49,9 +49,6 @@ class Apriori implements Associator
 
     /**
      * Apriori constructor.
-     *
-     * @param float $support
-     * @param float $confidence
      */
     public function __construct(float $support = 0.0, float $confidence = 0.0)
     {
@@ -261,8 +258,6 @@ class Apriori implements Associator
      *
      * @param mixed[] $set
      * @param mixed[] $subset
-     *
-     * @return float
      */
     private function confidence(array $set, array $subset) : float
     {
@@ -276,8 +271,6 @@ class Apriori implements Associator
      * @see \Phpml\Association\Apriori::samples
      *
      * @param mixed[] $sample
-     *
-     * @return float
      */
     private function support(array $sample) : float
     {
@@ -290,8 +283,6 @@ class Apriori implements Associator
      * @see \Phpml\Association\Apriori::samples
      *
      * @param mixed[] $sample
-     *
-     * @return int
      */
     private function frequency(array $sample) : int
     {
@@ -307,8 +298,6 @@ class Apriori implements Associator
      *
      * @param mixed[][] $system
      * @param mixed[]   $set
-     *
-     * @return bool
      */
     private function contains(array $system, array $set) : bool
     {
@@ -322,8 +311,6 @@ class Apriori implements Associator
      *
      * @param mixed[] $set
      * @param mixed[] $subset
-     *
-     * @return bool
      */
     private function subset(array $set, array $subset) : bool
     {
@@ -335,8 +322,6 @@ class Apriori implements Associator
      *
      * @param mixed[] $set1
      * @param mixed[] $set2
-     *
-     * @return bool
      */
     private function equals(array $set1, array $set2) : bool
     {

src/Phpml/Classification/DecisionTree.php

@@ -4,11 +4,11 @@ declare(strict_types=1);
 
 namespace Phpml\Classification;
 
+use Phpml\Classification\DecisionTree\DecisionTreeLeaf;
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\Helper\Predictable;
 use Phpml\Helper\Trainable;
 use Phpml\Math\Statistic\Mean;
-use Phpml\Classification\DecisionTree\DecisionTreeLeaf;
 
 class DecisionTree implements Classifier
 {
@@ -63,14 +63,10 @@ class DecisionTree implements Classifier
     private $featureImportances = null;
 
     /**
-     *
      * @var array
      */
     private $columnNames = null;
 
-    /**
-     * @param int $maxDepth
-     */
     public function __construct(int $maxDepth = 10)
     {
         $this->maxDepth = $maxDepth;
@@ -129,8 +125,6 @@ class DecisionTree implements Classifier
     /**
      * @param array $records
      * @param int   $depth
-     *
-     * @return DecisionTreeLeaf
      */
     protected function getSplitLeaf(array $records, int $depth = 0) : DecisionTreeLeaf
     {
@@ -190,11 +184,6 @@ class DecisionTree implements Classifier
         return $split;
     }
 
-    /**
-     * @param array $records
-     *
-     * @return DecisionTreeLeaf
-     */
     protected function getBestSplit(array $records) : DecisionTreeLeaf
     {
         $targets = array_intersect_key($this->targets, array_flip($records));
@@ -277,10 +266,6 @@ class DecisionTree implements Classifier
 
     /**
      * @param mixed $baseValue
-     * @param array $colValues
-     * @param array $targets
-     *
-     * @return float
      */
     public function getGiniIndex($baseValue, array $colValues, array $targets) : float
     {
@@ -342,8 +327,6 @@ class DecisionTree implements Classifier
 
     /**
      * @param array $columnValues
-     *
-     * @return bool
      */
     protected static function isCategoricalColumn(array $columnValues) : bool
     {
@@ -376,8 +359,6 @@ class DecisionTree implements Classifier
      * otherwise the given value will be used as a maximum for number of columns
      * randomly selected for each split operation.
      *
-     * @param int $numFeatures
-     *
      * @return $this
      *
      * @throws InvalidArgumentException
@@ -395,8 +376,6 @@ class DecisionTree implements Classifier
 
     /**
      * Used to set predefined features to consider while deciding which column to use for a split
-     *
-     * @param array $selectedFeatures
      */
     protected function setSelectedFeatures(array $selectedFeatures)
     {
@@ -407,8 +386,6 @@ class DecisionTree implements Classifier
      * A string array to represent columns. Useful when HTML output or
      * column importances are desired to be inspected.
      *
-     * @param array $names
-     *
      * @return $this
      *
      * @throws InvalidArgumentException
@@ -424,10 +401,7 @@ class DecisionTree implements Classifier
         return $this;
     }
 
-    /**
+    public function getHtml() : string
-     * @return string
-     */
-    public function getHtml()
     {
         return $this->tree->getHTML($this->columnNames);
     }
@@ -436,10 +410,8 @@ class DecisionTree implements Classifier
      * This will return an array including an importance value for
      * each column in the given dataset. The importance values are
      * normalized and their total makes 1.<br/>
-     *
-     * @return array
      */
-    public function getFeatureImportances()
+    public function getFeatureImportances() : array
     {
         if ($this->featureImportances !== null) {
             return $this->featureImportances;
@@ -473,11 +445,6 @@ class DecisionTree implements Classifier
     /**
      * Collects and returns an array of internal nodes that use the given
      * column as a split criterion
-     *
-     * @param int              $column
-     * @param DecisionTreeLeaf $node
-     *
-     * @return array
      */
     protected function getSplitNodesByColumn(int $column, DecisionTreeLeaf $node) : array
     {
@@ -506,8 +473,6 @@ class DecisionTree implements Classifier
     }
 
     /**
-     * @param array $sample
-     *
      * @return mixed
      */
     protected function predictSample(array $sample)

src/Phpml/Classification/DecisionTree/DecisionTreeLeaf.php

@@ -71,12 +71,7 @@ class DecisionTreeLeaf
      */
     public $level = 0;
 
-    /**
+    public function evaluate(array $record) : bool
-     * @param array $record
-     *
-     * @return bool
-     */
-    public function evaluate($record)
     {
         $recordField = $record[$this->columnIndex];
 
@@ -90,12 +85,8 @@ class DecisionTreeLeaf
     /**
      * Returns Mean Decrease Impurity (MDI) in the node.
      * For terminal nodes, this value is equal to 0
-     *
-     * @param int $parentRecordCount
-     *
-     * @return float
      */
-    public function getNodeImpurityDecrease(int $parentRecordCount)
+    public function getNodeImpurityDecrease(int $parentRecordCount) : float
     {
         if ($this->isTerminal) {
             return 0.0;
@@ -119,12 +110,8 @@ class DecisionTreeLeaf
 
     /**
      * Returns HTML representation of the node including children nodes
-     *
-     * @param $columnNames
-     *
-     * @return string
      */
-    public function getHTML($columnNames = null)
+    public function getHTML($columnNames = null) : string
     {
         if ($this->isTerminal) {
             $value = "<b>$this->classValue</b>";
@@ -170,10 +157,8 @@ class DecisionTreeLeaf
 
     /**
      * HTML representation of the tree without column names
-     *
-     * @return string
      */
-    public function __toString()
+    public function __toString() : string
     {
         return $this->getHTML();
     }

src/Phpml/Classification/Ensemble/AdaBoost.php

@@ -4,13 +4,13 @@ declare(strict_types=1);
 
 namespace Phpml\Classification\Ensemble;
 
+use Phpml\Classification\Classifier;
 use Phpml\Classification\Linear\DecisionStump;
 use Phpml\Classification\WeightedClassifier;
-use Phpml\Math\Statistic\Mean;
-use Phpml\Math\Statistic\StandardDeviation;
-use Phpml\Classification\Classifier;
 use Phpml\Helper\Predictable;
 use Phpml\Helper\Trainable;
+use Phpml\Math\Statistic\Mean;
+use Phpml\Math\Statistic\StandardDeviation;
 
 class AdaBoost implements Classifier
 {
@@ -75,8 +75,6 @@ class AdaBoost implements Classifier
      * ADAptive BOOSTing (AdaBoost) is an ensemble algorithm to
      * improve classification performance of 'weak' classifiers such as
      * DecisionStump (default base classifier of AdaBoost).
-     *
-     * @param int $maxIterations
      */
     public function __construct(int $maxIterations = 50)
     {
@@ -85,9 +83,6 @@ class AdaBoost implements Classifier
 
     /**
      * Sets the base classifier that will be used for boosting (default = DecisionStump)
-     *
-     * @param string $baseClassifier
-     * @param array  $classifierOptions
      */
     public function setBaseClassifier(string $baseClassifier = DecisionStump::class, array $classifierOptions = [])
     {
@@ -96,9 +91,6 @@ class AdaBoost implements Classifier
     }
 
     /**
-     * @param array $samples
-     * @param array $targets
-     *
      * @throws \Exception
      */
     public function train(array $samples, array $targets)
@@ -143,10 +135,8 @@ class AdaBoost implements Classifier
     /**
      * Returns the classifier with the lowest error rate with the
      * consideration of current sample weights
-     *
-     * @return Classifier
      */
-    protected function getBestClassifier()
+    protected function getBestClassifier() : Classifier
     {
         $ref = new \ReflectionClass($this->baseClassifier);
         if ($this->classifierOptions) {
@@ -169,10 +159,8 @@ class AdaBoost implements Classifier
     /**
      * Resamples the dataset in accordance with the weights and
      * returns the new dataset
-     *
-     * @return array
      */
-    protected function resample()
+    protected function resample() : array
     {
         $weights = $this->weights;
         $std = StandardDeviation::population($weights);
@@ -198,12 +186,8 @@ class AdaBoost implements Classifier
 
     /**
      * Evaluates the classifier and returns the classification error rate
-     *
-     * @param Classifier $classifier
-     *
-     * @return float
      */
-    protected function evaluateClassifier(Classifier $classifier)
+    protected function evaluateClassifier(Classifier $classifier) : float
     {
         $total = (float) array_sum($this->weights);
         $wrong = 0;
@@ -219,12 +203,8 @@ class AdaBoost implements Classifier
 
     /**
      * Calculates alpha of a classifier
-     *
-     * @param float $errorRate
-     *
-     * @return float
      */
-    protected function calculateAlpha(float $errorRate)
+    protected function calculateAlpha(float $errorRate) : float
     {
         if ($errorRate == 0) {
             $errorRate = 1e-10;
@@ -235,9 +215,6 @@ class AdaBoost implements Classifier
 
     /**
      * Updates the sample weights
-     *
-     * @param Classifier $classifier
-     * @param float      $alpha
      */
     protected function updateWeights(Classifier $classifier, float $alpha)
     {
@@ -256,8 +233,6 @@ class AdaBoost implements Classifier
     }
 
     /**
-     * @param array $sample
-     *
      * @return mixed
      */
     public function predictSample(array $sample)

src/Phpml/Classification/Ensemble/Bagging.php

@@ -4,10 +4,10 @@ declare(strict_types=1);
 
 namespace Phpml\Classification\Ensemble;
 
-use Phpml\Helper\Predictable;
-use Phpml\Helper\Trainable;
 use Phpml\Classification\Classifier;
 use Phpml\Classification\DecisionTree;
+use Phpml\Helper\Predictable;
+use Phpml\Helper\Trainable;
 
 class Bagging implements Classifier
 {
@@ -62,8 +62,6 @@ class Bagging implements Classifier
      * Creates an ensemble classifier with given number of base classifiers
      * Default number of base classifiers is 50.
      * The more number of base classifiers, the better performance but at the cost of procesing time
-     *
-     * @param int $numClassifier
      */
     public function __construct(int $numClassifier = 50)
     {
@@ -75,8 +73,6 @@ class Bagging implements Classifier
      * e.g., random samples drawn from the original dataset with replacement (allow repeats),
      * to train each base classifier.
      *
-     * @param float $ratio
-     *
      * @return $this
      *
      * @throws \Exception
@@ -100,9 +96,6 @@ class Bagging implements Classifier
      * given in the order they are in the constructor of the classifier and parameter
      * names are neglected.
      *
-     * @param string $classifier
-     * @param array  $classifierOptions
-     *
      * @return $this
      */
     public function setClassifer(string $classifier, array $classifierOptions = [])
@@ -113,10 +106,6 @@ class Bagging implements Classifier
         return $this;
     }
 
-    /**
-     * @param array $samples
-     * @param array $targets
-     */
     public function train(array $samples, array $targets)
     {
         $this->samples = array_merge($this->samples, $samples);
@@ -134,12 +123,7 @@ class Bagging implements Classifier
         }
     }
 
-    /**
+    protected function getRandomSubset(int $index) : array
-     * @param int $index
-     *
-     * @return array
-     */
-    protected function getRandomSubset(int $index)
     {
         $samples = [];
         $targets = [];
@@ -154,10 +138,7 @@ class Bagging implements Classifier
         return [$samples, $targets];
     }
 
-    /**
+    protected function initClassifiers() : array
-     * @return array
-     */
-    protected function initClassifiers()
     {
         $classifiers = [];
         for ($i = 0; $i < $this->numClassifier; ++$i) {
@@ -185,8 +166,6 @@ class Bagging implements Classifier
     }
 
     /**
-     * @param array $sample
-     *
      * @return mixed
      */
     protected function predictSample(array $sample)

src/Phpml/Classification/Ensemble/RandomForest.php

@@ -22,8 +22,6 @@ class RandomForest extends Bagging
      * Initializes RandomForest with the given number of trees. More trees
      * may increase the prediction performance while it will also substantially
      * increase the processing time and the required memory
-     *
-     * @param int $numClassifier
      */
     public function __construct(int $numClassifier = 50)
     {
@@ -65,9 +63,6 @@ class RandomForest extends Bagging
     /**
      * RandomForest algorithm is usable *only* with DecisionTree
      *
-     * @param string $classifier
-     * @param array  $classifierOptions
-     *
      * @return $this
      *
      * @throws \Exception
@@ -85,10 +80,8 @@ class RandomForest extends Bagging
      * This will return an array including an importance value for
      * each column in the given dataset. Importance values for a column
      * is the average importance of that column in all trees in the forest
-     *
-     * @return array
      */
-    public function getFeatureImportances()
+    public function getFeatureImportances() : array
     {
         // Traverse each tree and sum importance of the columns
         $sum = [];
@@ -120,8 +113,6 @@ class RandomForest extends Bagging
      * A string array to represent the columns is given. They are useful
      * when trying to print some information about the trees such as feature importances
      *
-     * @param array $names
-     *
      * @return $this
      */
     public function setColumnNames(array $names)

src/Phpml/Classification/KNearestNeighbors.php

@@ -24,7 +24,6 @@ class KNearestNeighbors implements Classifier
     private $distanceMetric;
 
     /**
-     * @param int           $k
      * @param Distance|null $distanceMetric (if null then Euclidean distance as default)
      */
     public function __construct(int $k = 3, Distance $distanceMetric = null)
@@ -40,8 +39,6 @@ class KNearestNeighbors implements Classifier
     }
 
     /**
-     * @param array $sample
-     *
      * @return mixed
      */
     protected function predictSample(array $sample)
@@ -61,13 +58,9 @@ class KNearestNeighbors implements Classifier
     }
 
     /**
-     * @param array $sample
-     *
-     * @return array
-     *
      * @throws \Phpml\Exception\InvalidArgumentException
      */
-    private function kNeighborsDistances(array $sample)
+    private function kNeighborsDistances(array $sample) : array
     {
         $distances = [];
 

src/Phpml/Classification/Linear/Adaline.php

@@ -32,11 +32,6 @@ class Adaline extends Perceptron
      * If normalizeInputs is set to true, then every input given to the algorithm will be standardized
      * by use of standard deviation and mean calculation
      *
-     * @param float $learningRate
-     * @param int   $maxIterations
-     * @param bool  $normalizeInputs
-     * @param int   $trainingType
-     *
      * @throws \Exception
      */
     public function __construct(
@@ -57,8 +52,6 @@ class Adaline extends Perceptron
     /**
      * Adapts the weights with respect to given samples and targets
      * by use of gradient descent learning rule
-     *
-     * @param array $samples
      * @param array $targets
      */
     protected function runTraining(array $samples, array $targets)

src/Phpml/Classification/Linear/DecisionStump.php

@@ -4,10 +4,10 @@ declare(strict_types=1);
 
 namespace Phpml\Classification\Linear;
 
-use Phpml\Helper\Predictable;
-use Phpml\Helper\OneVsRest;
-use Phpml\Classification\WeightedClassifier;
 use Phpml\Classification\DecisionTree;
+use Phpml\Classification\WeightedClassifier;
+use Phpml\Helper\OneVsRest;
+use Phpml\Helper\Predictable;
 use Phpml\Math\Comparison;
 
 class DecisionStump extends WeightedClassifier
@@ -77,8 +77,6 @@ class DecisionStump extends WeightedClassifier
      * If columnIndex is given, then the stump tries to produce a decision node
      * on this column, otherwise in cases given the value of -1, the stump itself
      * decides which column to take for the decision (Default DecisionTree behaviour)
-     *
-     * @param int $columnIndex
      */
     public function __construct(int $columnIndex = self::AUTO_SELECT)
     {
@@ -86,10 +84,6 @@ class DecisionStump extends WeightedClassifier
     }
 
     /**
-     * @param array $samples
-     * @param array $targets
-     * @param array $labels
-     *
      * @throws \Exception
      */
     protected function trainBinary(array $samples, array $targets, array $labels)
@@ -151,8 +145,6 @@ class DecisionStump extends WeightedClassifier
      * values in the column. Given <i>$count</i> value determines how many split
      * points to be probed. The more split counts, the better performance but
      * worse processing time (Default value is 10.0)
-     *
-     * @param float $count
      */
     public function setNumericalSplitCount(float $count)
     {
@@ -161,14 +153,8 @@ class DecisionStump extends WeightedClassifier
 
     /**
      * Determines best split point for the given column
-     *
-     * @param array $samples
-     * @param array $targets
-     * @param int   $col
-     *
-     * @return array
      */
-    protected function getBestNumericalSplit(array $samples, array $targets, int $col)
+    protected function getBestNumericalSplit(array $samples, array $targets, int $col) : array
     {
         $values = array_column($samples, $col);
         // Trying all possible points may be accomplished in two general ways:
@@ -207,13 +193,6 @@ class DecisionStump extends WeightedClassifier
         return $split;
     }
 
-    /**
-     * @param array $samples
-     * @param array $targets
-     * @param int   $col
-     *
-     * @return array
-     */
     protected function getBestNominalSplit(array $samples, array $targets, int $col) : array
     {
         $values = array_column($samples, $col);
@@ -240,13 +219,6 @@ class DecisionStump extends WeightedClassifier
     /**
      * Calculates the ratio of wrong predictions based on the new threshold
      * value given as the parameter
-     *
-     * @param array  $targets
-     * @param float  $threshold
-     * @param string $operator
-     * @param array  $values
-     *
-     * @return array
      */
     protected function calculateErrorRate(array $targets, float $threshold, string $operator, array $values) : array
     {
@@ -293,10 +265,7 @@ class DecisionStump extends WeightedClassifier
      * Probability of a sample is calculated as the proportion of the label
      * within the labels of the training samples in the decision node
      *
-     * @param array $sample
      * @param mixed $label
-     *
-     * @return float
      */
     protected function predictProbability(array $sample, $label) : float
     {
@@ -309,8 +278,6 @@ class DecisionStump extends WeightedClassifier
     }
 
     /**
-     * @param array $sample
-     *
      * @return mixed
      */
     protected function predictSampleBinary(array $sample)
@@ -322,17 +289,11 @@ class DecisionStump extends WeightedClassifier
         return $this->binaryLabels[1];
     }
 
-    /**
-     * @return void
-     */
     protected function resetBinary()
     {
     }
 
-    /**
+    public function __toString() : string
-     * @return string
-     */
-    public function __toString()
     {
         return "IF $this->column $this->operator $this->value ".
             'THEN '.$this->binaryLabels[0].' '.

src/Phpml/Classification/Linear/LogisticRegression.php

@@ -59,12 +59,6 @@ class LogisticRegression extends Adaline
      *
      * Penalty (Regularization term) can be 'L2' or empty string to cancel penalty term
      *
-     * @param int    $maxIterations
-     * @param bool   $normalizeInputs
-     * @param int    $trainingType
-     * @param string $cost
-     * @param string $penalty
-     *
      * @throws \Exception
      */
     public function __construct(
@@ -102,8 +96,6 @@ class LogisticRegression extends Adaline
     /**
      * Sets the learning rate if gradient descent algorithm is
      * selected for training
-     *
-     * @param float $learningRate
      */
     public function setLearningRate(float $learningRate)
     {
@@ -113,8 +105,6 @@ class LogisticRegression extends Adaline
     /**
      * Lambda (λ) parameter of regularization term. If 0 is given,
      * then the regularization term is cancelled
-     *
-     * @param float $lambda
      */
     public function setLambda(float $lambda)
     {
@@ -125,9 +115,6 @@ class LogisticRegression extends Adaline
      * Adapts the weights with respect to given samples and targets
      * by use of selected solver
      *
-     * @param array $samples
-     * @param array $targets
-     *
      * @throws \Exception
      */
     protected function runTraining(array $samples, array $targets)
@@ -154,7 +141,6 @@ class LogisticRegression extends Adaline
      *
      * @param array    $samples
      * @param array    $targets
-     * @param \Closure $gradientFunc
      */
     protected function runConjugateGradient(array $samples, array $targets, \Closure $gradientFunc)
     {
@@ -170,11 +156,9 @@ class LogisticRegression extends Adaline
     /**
      * Returns the appropriate callback function for the selected cost function
      *
-     * @return \Closure
-     *
      * @throws \Exception
      */
-    protected function getCostFunction()
+    protected function getCostFunction() : \Closure
     {
         $penalty = 0;
         if ($this->penalty == 'L2') {
@@ -244,8 +228,6 @@ class LogisticRegression extends Adaline
     /**
      * Returns the output of the network, a float value between 0.0 and 1.0
      *
-     * @param array $sample
-     *
      * @return float
      */
     protected function output(array $sample)
@@ -257,12 +239,8 @@ class LogisticRegression extends Adaline
 
     /**
      * Returns the class value (either -1 or 1) for the given input
-     *
-     * @param array $sample
-     *
-     * @return int
      */
-    protected function outputClass(array $sample)
+    protected function outputClass(array $sample) : int
     {
         $output = $this->output($sample);
 
@@ -278,20 +256,17 @@ class LogisticRegression extends Adaline
      *
      * The probability is simply taken as the distance of the sample
      * to the decision plane.
-     *
+
-     * @param array $sample
      * @param mixed $label
-     *
-     * @return float
      */
-    protected function predictProbability(array $sample, $label)
+    protected function predictProbability(array $sample, $label) : float
     {
         $predicted = $this->predictSampleBinary($sample);
 
         if ((string) $predicted == (string) $label) {
             $sample = $this->checkNormalizedSample($sample);
 
-            return abs($this->output($sample) - 0.5);
+            return (float) abs($this->output($sample) - 0.5);
         }
 
         return 0.0;

src/Phpml/Classification/Linear/Perceptron.php

@@ -4,13 +4,13 @@ declare(strict_types=1);
 
 namespace Phpml\Classification\Linear;
 
-use Phpml\Helper\Predictable;
-use Phpml\Helper\OneVsRest;
-use Phpml\Helper\Optimizer\StochasticGD;
-use Phpml\Helper\Optimizer\GD;
 use Phpml\Classification\Classifier;
-use Phpml\Preprocessing\Normalizer;
+use Phpml\Helper\OneVsRest;
+use Phpml\Helper\Optimizer\GD;
+use Phpml\Helper\Optimizer\StochasticGD;
+use Phpml\Helper\Predictable;
 use Phpml\IncrementalEstimator;
+use Phpml\Preprocessing\Normalizer;
 
 class Perceptron implements Classifier, IncrementalEstimator
 {
@@ -67,7 +67,6 @@ class Perceptron implements Classifier, IncrementalEstimator
      *
      * @param float $learningRate    Value between 0.0(exclusive) and 1.0(inclusive)
      * @param int   $maxIterations   Must be at least 1
-     * @param bool  $normalizeInputs
      *
      * @throws \Exception
      */
@@ -89,21 +88,11 @@ class Perceptron implements Classifier, IncrementalEstimator
         $this->maxIterations = $maxIterations;
     }
 
-    /**
-     * @param array $samples
-     * @param array $targets
-     * @param array $labels
-     */
     public function partialTrain(array $samples, array $targets, array $labels = [])
     {
         $this->trainByLabel($samples, $targets, $labels);
     }
 
-    /**
-      * @param array $samples
-      * @param array $targets
-      * @param array $labels
-      */
     public function trainBinary(array $samples, array $targets, array $labels)
     {
         if ($this->normalizer) {
@@ -139,8 +128,6 @@ class Perceptron implements Classifier, IncrementalEstimator
      * If "false" is given, the optimization procedure will always be executed
      * for $maxIterations times
      *
-     * @param bool $enable
-     *
      * @return $this
      */
     public function setEarlyStop(bool $enable = true)
@@ -152,10 +139,8 @@ class Perceptron implements Classifier, IncrementalEstimator
 
     /**
      * Returns the cost values obtained during the training.
-     *
-     * @return array
      */
-    public function getCostValues()
+    public function getCostValues() : array
     {
         return $this->costValues;
     }
@@ -163,9 +148,6 @@ class Perceptron implements Classifier, IncrementalEstimator
     /**
      * Trains the perceptron model with Stochastic Gradient Descent optimization
      * to get the correct set of weights
-     *
-     * @param array $samples
-     * @param array $targets
      */
     protected function runTraining(array $samples, array $targets)
     {
@@ -186,11 +168,6 @@ class Perceptron implements Classifier, IncrementalEstimator
     /**
      * Executes a Gradient Descent algorithm for
      * the given cost function
-     *
-     * @param array    $samples
-     * @param array    $targets
-     * @param \Closure $gradientFunc
-     * @param bool     $isBatch
      */
     protected function runGradientDescent(array $samples, array $targets, \Closure $gradientFunc, bool $isBatch = false)
     {
@@ -211,12 +188,8 @@ class Perceptron implements Classifier, IncrementalEstimator
     /**
      * Checks if the sample should be normalized and if so, returns the
      * normalized sample
-     *
-     * @param array $sample
-     *
-     * @return array
      */
-    protected function checkNormalizedSample(array $sample)
+    protected function checkNormalizedSample(array $sample) : array
     {
         if ($this->normalizer) {
             $samples = [$sample];
@@ -230,8 +203,6 @@ class Perceptron implements Classifier, IncrementalEstimator
     /**
      * Calculates net output of the network as a float value for the given input
      *
-     * @param array $sample
-     *
      * @return int
      */
     protected function output(array $sample)
@@ -250,12 +221,8 @@ class Perceptron implements Classifier, IncrementalEstimator
 
     /**
      * Returns the class value (either -1 or 1) for the given input
-     *
-     * @param array $sample
-     *
-     * @return int
      */
-    protected function outputClass(array $sample)
+    protected function outputClass(array $sample) : int
     {
         return $this->output($sample) > 0 ? 1 : -1;
     }
@@ -266,27 +233,22 @@ class Perceptron implements Classifier, IncrementalEstimator
      * The probability is simply taken as the distance of the sample
      * to the decision plane.
      *
-     * @param array $sample
      * @param mixed $label
-     *
-     * @return float
      */
-    protected function predictProbability(array $sample, $label)
+    protected function predictProbability(array $sample, $label) : float
     {
         $predicted = $this->predictSampleBinary($sample);
 
         if ((string) $predicted == (string) $label) {
             $sample = $this->checkNormalizedSample($sample);
 
-            return abs($this->output($sample));
+            return (float) abs($this->output($sample));
         }
 
         return 0.0;
     }
 
     /**
-     * @param array $sample
-     *
      * @return mixed
      */
     protected function predictSampleBinary(array $sample)

src/Phpml/Classification/MLPClassifier.php

@@ -13,10 +13,8 @@ class MLPClassifier extends MultilayerPerceptron implements Classifier
      * @param mixed $target
      *
      * @throws InvalidArgumentException
-     *
-     * @return int
      */
-    public function getTargetClass($target): int
+    public function getTargetClass($target) : int
     {
         if (!in_array($target, $this->classes)) {
             throw InvalidArgumentException::invalidTarget($target);
@@ -26,8 +24,6 @@ class MLPClassifier extends MultilayerPerceptron implements Classifier
     }
 
     /**
-     * @param array $sample
-     *
      * @return mixed
      */
     protected function predictSample(array $sample)
@@ -47,7 +43,6 @@ class MLPClassifier extends MultilayerPerceptron implements Classifier
     }
 
     /**
-     * @param array $sample
      * @param mixed $target
      */
     protected function trainSample(array $sample, $target)

src/Phpml/Classification/NaiveBayes.php

@@ -57,10 +57,6 @@ class NaiveBayes implements Classifier
      */
     private $labels = [];
 
-    /**
-     * @param array $samples
-     * @param array $targets
-     */
     public function train(array $samples, array $targets)
     {
         $this->samples = array_merge($this->samples, $samples);
@@ -80,11 +76,8 @@ class NaiveBayes implements Classifier
     /**
      * Calculates vital statistics for each label & feature. Stores these
      * values in private array in order to avoid repeated calculation
-     *
-     * @param string $label
-     * @param array  $samples
      */
-    private function calculateStatistics($label, $samples)
+    private function calculateStatistics(string $label, array $samples)
     {
         $this->std[$label] = array_fill(0, $this->featureCount, 0);
         $this->mean[$label] = array_fill(0, $this->featureCount, 0);
@@ -114,14 +107,8 @@ class NaiveBayes implements Classifier
 
     /**
      * Calculates the probability P(label|sample_n)
-     *
-     * @param array  $sample
-     * @param int    $feature
-     * @param string $label
-     *
-     * @return float
      */
-    private function sampleProbability($sample, $feature, $label)
+    private function sampleProbability(array $sample, int $feature, string $label) : float
     {
         $value = $sample[$feature];
         if ($this->dataType[$label][$feature] == self::NOMINAL) {
@@ -149,12 +136,8 @@ class NaiveBayes implements Classifier
 
     /**
      * Return samples belonging to specific label
-     *
-     * @param string $label
-     *
-     * @return array
      */
-    private function getSamplesByLabel($label)
+    private function getSamplesByLabel(string $label) : array
     {
         $samples = [];
         for ($i = 0; $i < $this->sampleCount; ++$i) {
@@ -167,8 +150,6 @@ class NaiveBayes implements Classifier
     }
 
     /**
-     * @param array $sample
-     *
      * @return mixed
      */
     protected function predictSample(array $sample)

src/Phpml/Classification/SVC.php

@@ -10,17 +10,6 @@ use Phpml\SupportVectorMachine\Type;
 
 class SVC extends SupportVectorMachine implements Classifier
 {
-    /**
-     * @param int        $kernel
-     * @param float      $cost
-     * @param int        $degree
-     * @param float|null $gamma
-     * @param float      $coef0
-     * @param float      $tolerance
-     * @param int        $cacheSize
-     * @param bool       $shrinking
-     * @param bool       $probabilityEstimates
-     */
     public function __construct(
         int $kernel = Kernel::LINEAR,
         float $cost = 1.0,

src/Phpml/Clustering/Clusterer.php

@@ -6,10 +6,5 @@ namespace Phpml\Clustering;
 
 interface Clusterer
 {
-    /**
+    public function cluster(array $samples) : array;
-     * @param array $samples
-     *
-     * @return array
-     */
-    public function cluster(array $samples);
 }

src/Phpml/Clustering/DBSCAN.php

@@ -24,12 +24,7 @@ class DBSCAN implements Clusterer
      */
     private $distanceMetric;
 
-    /**
+    public function __construct(float $epsilon = 0.5, int $minSamples = 3, Distance $distanceMetric = null)
-     * @param float    $epsilon
-     * @param int      $minSamples
-     * @param Distance $distanceMetric
-     */
-    public function __construct($epsilon = 0.5, $minSamples = 3, Distance $distanceMetric = null)
     {
         if (null === $distanceMetric) {
             $distanceMetric = new Euclidean();
@@ -40,12 +35,7 @@ class DBSCAN implements Clusterer
         $this->distanceMetric = $distanceMetric;
     }
 
-    /**
+    public function cluster(array $samples) : array
-     * @param array $samples
-     *
-     * @return array
-     */
-    public function cluster(array $samples)
     {
         $clusters = [];
         $visited = [];
@@ -65,13 +55,7 @@ class DBSCAN implements Clusterer
         return $clusters;
     }
 
-    /**
+    private function getSamplesInRegion(array $localSample, array $samples) : array
-     * @param array $localSample
-     * @param array $samples
-     *
-     * @return array
-     */
-    private function getSamplesInRegion($localSample, $samples)
     {
         $region = [];
 
@@ -84,13 +68,7 @@ class DBSCAN implements Clusterer
         return $region;
     }
 
-    /**
+    private function expandCluster(array $samples, array &$visited) : array
-     * @param array $samples
-     * @param array $visited
-     *
-     * @return array
-     */
-    private function expandCluster($samples, &$visited)
     {
         $cluster = [];
 

src/Phpml/Clustering/FuzzyCMeans.php

@@ -4,8 +4,8 @@ declare(strict_types=1);
 
 namespace Phpml\Clustering;
 
-use Phpml\Clustering\KMeans\Point;
 use Phpml\Clustering\KMeans\Cluster;
+use Phpml\Clustering\KMeans\Point;
 use Phpml\Clustering\KMeans\Space;
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\Math\Distance\Euclidean;
@@ -58,11 +58,6 @@ class FuzzyCMeans implements Clusterer
     private $samples;
 
     /**
-     * @param int   $clustersNumber
-     * @param float $fuzziness
-     * @param float $epsilon
-     * @param int   $maxIterations
-     *
      * @throws InvalidArgumentException
      */
     public function __construct(int $clustersNumber, float $fuzziness = 2.0, float $epsilon = 1e-2, int $maxIterations = 100)
@@ -85,10 +80,6 @@ class FuzzyCMeans implements Clusterer
         $this->updateClusters();
     }
 
-    /**
-     * @param int $rows
-     * @param int $cols
-     */
     protected function generateRandomMembership(int $rows, int $cols)
     {
         $this->membership = [];
@@ -155,14 +146,7 @@ class FuzzyCMeans implements Clusterer
         }
     }
 
-    /**
+    protected function getDistanceCalc(int $row, int $col) : float
-     *
-     * @param int $row
-     * @param int $col
-     *
-     * @return float
-     */
-    protected function getDistanceCalc(int $row, int $col)
     {
         $sum = 0.0;
         $distance = new Euclidean();
@@ -204,20 +188,15 @@ class FuzzyCMeans implements Clusterer
         return $sum;
     }
 
-    /**
+    public function getMembershipMatrix() : array
-     * @return array
-     */
-    public function getMembershipMatrix()
     {
         return $this->membership;
     }
 
     /**
      * @param array|Point[] $samples
-     *
-     * @return array
      */
-    public function cluster(array $samples)
+    public function cluster(array $samples) : array
     {
         // Initialize variables, clusters and membership matrix
         $this->sampleCount = count($samples);

src/Phpml/Clustering/KMeans.php

@@ -22,12 +22,6 @@ class KMeans implements Clusterer
      */
     private $initialization;
 
-    /**
-     * @param int $clustersNumber
-     * @param int $initialization
-     *
-     * @throws InvalidArgumentException
-     */
     public function __construct(int $clustersNumber, int $initialization = self::INIT_KMEANS_PLUS_PLUS)
     {
         if ($clustersNumber <= 0) {
@@ -38,12 +32,7 @@ class KMeans implements Clusterer
         $this->initialization = $initialization;
     }
 
-    /**
+    public function cluster(array $samples) : array
-     * @param array $samples
-     *
-     * @return array
-     */
-    public function cluster(array $samples)
     {
         $space = new Space(count($samples[0]));
         foreach ($samples as $sample) {

src/Phpml/Clustering/KMeans/Cluster.php

@@ -4,10 +4,10 @@ declare(strict_types=1);
 
 namespace Phpml\Clustering\KMeans;
 
-use IteratorAggregate;
 use Countable;
-use SplObjectStorage;
+use IteratorAggregate;
 use LogicException;
+use SplObjectStorage;
 
 class Cluster extends Point implements IteratorAggregate, Countable
 {
@@ -21,10 +21,6 @@ class Cluster extends Point implements IteratorAggregate, Countable
      */
     protected $points;
 
-    /**
-     * @param Space $space
-     * @param array $coordinates
-     */
     public function __construct(Space $space, array $coordinates)
     {
         parent::__construct($coordinates);
@@ -32,10 +28,7 @@ class Cluster extends Point implements IteratorAggregate, Countable
         $this->points = new SplObjectStorage();
     }
 
-    /**
+    public function getPoints() : array
-     * @return array
-     */
-    public function getPoints()
     {
         $points = [];
         foreach ($this->points as $point) {
@@ -45,10 +38,7 @@ class Cluster extends Point implements IteratorAggregate, Countable
         return $points;
     }
 
-    /**
+    public function toArray() : array
-     * @return array
-     */
-    public function toArray()
     {
         return [
             'centroid' => parent::toArray(),
@@ -56,14 +46,7 @@ class Cluster extends Point implements IteratorAggregate, Countable
         ];
     }
 
-    /**
+    public function attach(Point $point) : Point
-     * @param Point $point
-     *
-     * @return Point
-     *
-     * @throws \LogicException
-     */
-    public function attach(Point $point)
     {
         if ($point instanceof self) {
             throw new LogicException('cannot attach a cluster to another');
@@ -74,29 +57,18 @@ class Cluster extends Point implements IteratorAggregate, Countable
         return $point;
     }
 
-    /**
+    public function detach(Point $point) : Point
-     * @param Point $point
-     *
-     * @return Point
-     */
-    public function detach(Point $point)
     {
         $this->points->detach($point);
 
         return $point;
     }
 
-    /**
-     * @param SplObjectStorage $points
-     */
     public function attachAll(SplObjectStorage $points)
     {
         $this->points->addAll($points);
     }
 
-    /**
-     * @param SplObjectStorage $points
-     */
     public function detachAll(SplObjectStorage $points)
     {
         $this->points->removeAll($points);
@@ -137,9 +109,6 @@ class Cluster extends Point implements IteratorAggregate, Countable
         return count($this->points);
     }
 
-    /**
-    * @param array $newCoordinates
-    */
     public function setCoordinates(array $newCoordinates)
     {
         $this->coordinates = $newCoordinates;

src/Phpml/Clustering/KMeans/Point.php

@@ -18,30 +18,21 @@ class Point implements ArrayAccess
      */
     protected $coordinates;
 
-    /**
-     * @param array $coordinates
-     */
     public function __construct(array $coordinates)
     {
         $this->dimension = count($coordinates);
         $this->coordinates = $coordinates;
     }
 
-    /**
+    public function toArray() : array
-     * @return array
-     */
-    public function toArray()
     {
         return $this->coordinates;
     }
 
     /**
-     * @param Point $point
-     * @param bool  $precise
-     *
      * @return int|mixed
      */
-    public function getDistanceWith(self $point, $precise = true)
+    public function getDistanceWith(self $point, bool $precise = true)
     {
         $distance = 0;
         for ($n = 0; $n < $this->dimension; ++$n) {
@@ -53,8 +44,6 @@ class Point implements ArrayAccess
     }
 
     /**
-     * @param array $points
-     *
      * @return mixed
      */
     public function getClosest(array $points)
@@ -77,20 +66,15 @@ class Point implements ArrayAccess
         return $minPoint;
     }
 
-    /**
+    public function getCoordinates() : array
-     * @return array
-     */
-    public function getCoordinates()
     {
         return $this->coordinates;
     }
 
     /**
      * @param mixed $offset
-     *
-     * @return bool
      */
-    public function offsetExists($offset)
+    public function offsetExists($offset): bool
     {
         return isset($this->coordinates[$offset]);
     }

src/Phpml/Clustering/KMeans/Space.php

@@ -4,10 +4,10 @@ declare(strict_types=1);
 
 namespace Phpml\Clustering\KMeans;
 
+use InvalidArgumentException;
+use LogicException;
 use Phpml\Clustering\KMeans;
 use SplObjectStorage;
-use LogicException;
-use InvalidArgumentException;
 
 class Space extends SplObjectStorage
 {
@@ -16,9 +16,6 @@ class Space extends SplObjectStorage
      */
     protected $dimension;
 
-    /**
-     * @param $dimension
-     */
     public function __construct($dimension)
     {
         if ($dimension < 1) {
@@ -28,10 +25,7 @@ class Space extends SplObjectStorage
         $this->dimension = $dimension;
     }
 
-    /**
+    public function toArray() : array
-     * @return array
-     */
-    public function toArray()
     {
         $points = [];
         foreach ($this as $point) {
@@ -41,12 +35,7 @@ class Space extends SplObjectStorage
         return ['points' => $points];
     }
 
-    /**
+    public function newPoint(array $coordinates) : Point
-     * @param array $coordinates
-     *
-     * @return Point
-     */
-    public function newPoint(array $coordinates)
     {
         if (count($coordinates) != $this->dimension) {
             throw new LogicException('('.implode(',', $coordinates).') is not a point of this space');
@@ -56,7 +45,6 @@ class Space extends SplObjectStorage
     }
 
     /**
-     * @param array $coordinates
      * @param null  $data
      */
     public function addPoint(array $coordinates, $data = null)
@@ -77,10 +65,7 @@ class Space extends SplObjectStorage
         parent::attach($point, $data);
     }
 
-    /**
+    public function getDimension() : int
-     * @return int
-     */
-    public function getDimension()
     {
         return $this->dimension;
     }
@@ -107,13 +92,7 @@ class Space extends SplObjectStorage
         return [$min, $max];
     }
 
-    /**
+    public function getRandomPoint(Point $min, Point $max) : Point
-     * @param Point $min
-     * @param Point $max
-     *
-     * @return Point
-     */
-    public function getRandomPoint(Point $min, Point $max)
     {
         $point = $this->newPoint(array_fill(0, $this->dimension, null));
 
@@ -125,12 +104,9 @@ class Space extends SplObjectStorage
     }
 
     /**
-     * @param int $clustersNumber
-     * @param int $initMethod
-     *
      * @return array|Cluster[]
      */
-    public function cluster(int $clustersNumber, int $initMethod = KMeans::INIT_RANDOM)
+    public function cluster(int $clustersNumber, int $initMethod = KMeans::INIT_RANDOM) : array
     {
         $clusters = $this->initializeClusters($clustersNumber, $initMethod);
 
@@ -141,12 +117,9 @@ class Space extends SplObjectStorage
     }
 
     /**
-     * @param $clustersNumber
-     * @param $initMethod
-     *
      * @return array|Cluster[]
      */
-    protected function initializeClusters(int $clustersNumber, int $initMethod)
+    protected function initializeClusters(int $clustersNumber, int $initMethod) : array
     {
         switch ($initMethod) {
             case KMeans::INIT_RANDOM:
@@ -166,12 +139,7 @@ class Space extends SplObjectStorage
         return $clusters;
     }
 
-    /**
+    protected function iterate($clusters) : bool
-     * @param $clusters
-     *
-     * @return bool
-     */
-    protected function iterate($clusters)
     {
         $convergence = true;
 
@@ -209,12 +177,7 @@ class Space extends SplObjectStorage
         return $convergence;
     }
 
-    /**
+    private function initializeRandomClusters(int $clustersNumber) : array
-     * @param int $clustersNumber
-     *
-     * @return array
-     */
-    private function initializeRandomClusters(int $clustersNumber)
     {
         $clusters = [];
         list($min, $max) = $this->getBoundaries();
@@ -226,12 +189,7 @@ class Space extends SplObjectStorage
         return $clusters;
     }
 
-    /**
+    protected function initializeKMPPClusters(int $clustersNumber) : array
-     * @param int $clustersNumber
-     *
-     * @return array
-     */
-    protected function initializeKMPPClusters(int $clustersNumber)
     {
         $clusters = [];
         $this->rewind();

src/Phpml/CrossValidation/RandomSplit.php

@@ -8,10 +8,6 @@ use Phpml\Dataset\Dataset;
 
 class RandomSplit extends Split
 {
-    /**
-     * @param Dataset $dataset
-     * @param float   $testSize
-     */
     protected function splitDataset(Dataset $dataset, float $testSize)
     {
         $samples = $dataset->getSamples();

src/Phpml/CrossValidation/Split.php

@@ -29,13 +29,6 @@ abstract class Split
      */
     protected $testLabels = [];
 
-    /**
-     * @param Dataset $dataset
-     * @param float   $testSize
-     * @param int     $seed
-     *
-     * @throws InvalidArgumentException
-     */
     public function __construct(Dataset $dataset, float $testSize = 0.3, int $seed = null)
     {
         if (0 >= $testSize || 1 <= $testSize) {
@@ -48,41 +41,26 @@ abstract class Split
 
     abstract protected function splitDataset(Dataset $dataset, float $testSize);
 
-    /**
+    public function getTrainSamples() : array
-     * @return array
-     */
-    public function getTrainSamples()
     {
         return $this->trainSamples;
     }
 
-    /**
+    public function getTestSamples() : array
-     * @return array
-     */
-    public function getTestSamples()
     {
         return $this->testSamples;
     }
 
-    /**
+    public function getTrainLabels() : array
-     * @return array
-     */
-    public function getTrainLabels()
     {
         return $this->trainLabels;
     }
 
-    /**
+    public function getTestLabels() : array
-     * @return array
-     */
-    public function getTestLabels()
     {
         return $this->testLabels;
     }
 
-    /**
-     * @param int|null $seed
-     */
     protected function seedGenerator(int $seed = null)
     {
         if (null === $seed) {

src/Phpml/CrossValidation/StratifiedRandomSplit.php

@@ -9,10 +9,6 @@ use Phpml\Dataset\Dataset;
 
 class StratifiedRandomSplit extends RandomSplit
 {
-    /**
-     * @param Dataset $dataset
-     * @param float   $testSize
-     */
     protected function splitDataset(Dataset $dataset, float $testSize)
     {
         $datasets = $this->splitByTarget($dataset);
@@ -23,11 +19,9 @@ class StratifiedRandomSplit extends RandomSplit
     }
 
     /**
-     * @param Dataset $dataset
-     *
      * @return Dataset[]|array
      */
-    private function splitByTarget(Dataset $dataset): array
+    private function splitByTarget(Dataset $dataset) : array
     {
         $targets = $dataset->getTargets();
         $samples = $dataset->getSamples();
@@ -44,13 +38,7 @@ class StratifiedRandomSplit extends RandomSplit
         return $datasets;
     }
 
-    /**
+    private function createDatasets(array $uniqueTargets, array $split) : array
-     * @param array $uniqueTargets
-     * @param array $split
-     *
-     * @return array
-     */
-    private function createDatasets(array $uniqueTargets, array $split): array
     {
         $datasets = [];
         foreach ($uniqueTargets as $target) {

src/Phpml/Dataset/ArrayDataset.php

@@ -37,7 +37,7 @@ class ArrayDataset implements Dataset
     /**
      * @return array
      */
-    public function getSamples(): array
+    public function getSamples() : array
     {
         return $this->samples;
     }
@@ -45,7 +45,7 @@ class ArrayDataset implements Dataset
     /**
      * @return array
      */
-    public function getTargets(): array
+    public function getTargets() : array
     {
         return $this->targets;
     }

src/Phpml/Dataset/CsvDataset.php

@@ -14,12 +14,6 @@ class CsvDataset extends ArrayDataset
     protected $columnNames;
 
     /**
-     * @param string $filepath
-     * @param int    $features
-     * @param bool   $headingRow
-     * @param string $delimiter
-     * @param int    $maxLineLength
-     *
      * @throws FileException
      */
     public function __construct(string $filepath, int $features, bool $headingRow = true, string $delimiter = ',', int $maxLineLength = 0)
@@ -50,10 +44,7 @@ class CsvDataset extends ArrayDataset
         parent::__construct($samples, $targets);
     }
 
-    /**
+    public function getColumnNames() : array
-     * @return array
-     */
-    public function getColumnNames()
     {
         return $this->columnNames;
     }

src/Phpml/Dataset/Dataset.php

@@ -9,10 +9,10 @@ interface Dataset
     /**
      * @return array
      */
-    public function getSamples(): array;
+    public function getSamples() : array;
 
     /**
      * @return array
      */
-    public function getTargets(): array;
+    public function getTargets() : array;
 }

src/Phpml/Dataset/FilesDataset.php

@@ -8,11 +8,6 @@ use Phpml\Exception\DatasetException;
 
 class FilesDataset extends ArrayDataset
 {
-    /**
-     * @param string $rootPath
-     *
-     * @throws DatasetException
-     */
     public function __construct(string $rootPath)
     {
         if (!is_dir($rootPath)) {
@@ -22,9 +17,6 @@ class FilesDataset extends ArrayDataset
         $this->scanRootPath($rootPath);
     }
 
-    /**
-     * @param string $rootPath
-     */
     private function scanRootPath(string $rootPath)
     {
         foreach (glob($rootPath.DIRECTORY_SEPARATOR.'*', GLOB_ONLYDIR) as $dir) {
@@ -32,9 +24,6 @@ class FilesDataset extends ArrayDataset
         }
     }
 
-    /**
-     * @param string $dir
-     */
     private function scanDir(string $dir)
     {
         $target = basename($dir);

src/Phpml/DimensionReduction/EigenTransformerBase.php

@@ -90,7 +90,7 @@ abstract class EigenTransformerBase
      *
      * @return array
      */
-    protected function reduce(array $data)
+    protected function reduce(array $data) : array
     {
         $m1 = new Matrix($data);
         $m2 = new Matrix($this->eigVectors);

src/Phpml/DimensionReduction/KernelPCA.php

@@ -44,14 +44,13 @@ class KernelPCA extends PCA
      * will initialize the algorithm with an RBF kernel having the gamma parameter as 15,0. <br>
      * This transformation will return the same number of rows with only <i>2</i> columns.
      *
-     * @param int   $kernel
      * @param float $totalVariance Total variance to be preserved if numFeatures is not given
      * @param int   $numFeatures   Number of columns to be returned
      * @param float $gamma         Gamma parameter is used with RBF and Sigmoid kernels
      *
      * @throws \Exception
      */
-    public function __construct(int $kernel = self::KERNEL_RBF, $totalVariance = null, $numFeatures = null, $gamma = null)
+    public function __construct(int $kernel = self::KERNEL_RBF, float $totalVariance = null, int $numFeatures = null, float $gamma = null)
     {
         $availableKernels = [self::KERNEL_RBF, self::KERNEL_SIGMOID, self::KERNEL_LAPLACIAN, self::KERNEL_LINEAR];
         if (!in_array($kernel, $availableKernels)) {
@@ -69,12 +68,8 @@ class KernelPCA extends PCA
      * of this data while preserving $totalVariance or $numFeatures. <br>
      * $data is an n-by-m matrix and returned array is
      * n-by-k matrix where k <= m
-     *
-     * @param array $data
-     *
-     * @return array
      */
-    public function fit(array $data)
+    public function fit(array $data) : array
     {
         $numRows = count($data);
         $this->data = $data;
@@ -96,13 +91,8 @@ class KernelPCA extends PCA
     /**
      * Calculates similarity matrix by use of selected kernel function<br>
      * An n-by-m matrix is given and an n-by-n matrix is returned
-     *
-     * @param array $data
-     * @param int   $numRows
-     *
-     * @return array
      */
-    protected function calculateKernelMatrix(array $data, int $numRows)
+    protected function calculateKernelMatrix(array $data, int $numRows) : array
     {
         $kernelFunc = $this->getKernel();
 
@@ -125,13 +115,8 @@ class KernelPCA extends PCA
      * conversion:
      *
      * K′ = K − N.K −  K.N + N.K.N where N is n-by-n matrix filled with 1/n
-     *
-     * @param array $matrix
-     * @param int   $n
-     *
-     * @return array
      */
-    protected function centerMatrix(array $matrix, int $n)
+    protected function centerMatrix(array $matrix, int $n) : array
     {
         $N = array_fill(0, $n, array_fill(0, $n, 1.0 / $n));
         $N = new Matrix($N, false);
@@ -153,11 +138,9 @@ class KernelPCA extends PCA
     /**
      * Returns the callable kernel function
      *
-     * @return \Closure
-     *
      * @throws \Exception
      */
-    protected function getKernel()
+    protected function getKernel(): \Closure
     {
         switch ($this->kernel) {
             case self::KERNEL_LINEAR:
@@ -194,12 +177,7 @@ class KernelPCA extends PCA
         }
     }
 
-    /**
+    protected function getDistancePairs(array $sample) : array
-     * @param array $sample
-     *
-     * @return array
-     */
-    protected function getDistancePairs(array $sample)
     {
         $kernel = $this->getKernel();
 
@@ -211,12 +189,7 @@ class KernelPCA extends PCA
         return $pairs;
     }
 
-    /**
+    protected function projectSample(array $pairs) : array
-     * @param array $pairs
-     *
-     * @return array
-     */
-    protected function projectSample(array $pairs)
     {
         // Normalize eigenvectors by eig = eigVectors / eigValues
         $func = function ($eigVal, $eigVect) {
@@ -235,13 +208,9 @@ class KernelPCA extends PCA
      * Transforms the given sample to a lower dimensional vector by using
      * the variables obtained during the last run of <code>fit</code>.
      *
-     * @param array $sample
-     *
-     * @return array
-     *
      * @throws \Exception
      */
-    public function transform(array $sample)
+    public function transform(array $sample) : array
     {
         if (!$this->fit) {
             throw new \Exception('KernelPCA has not been fitted with respect to original dataset, please run KernelPCA::fit() first');

src/Phpml/DimensionReduction/LDA.php

@@ -47,7 +47,7 @@ class LDA extends EigenTransformerBase
      *
      * @throws \Exception
      */
-    public function __construct($totalVariance = null, $numFeatures = null)
+    public function __construct(float $totalVariance = null, int $numFeatures = null)
     {
         if ($totalVariance !== null && ($totalVariance < 0.1 || $totalVariance > 0.99)) {
             throw new \Exception('Total variance can be a value between 0.1 and 0.99');
@@ -69,11 +69,6 @@ class LDA extends EigenTransformerBase
 
     /**
      * Trains the algorithm to transform the given data to a lower dimensional space.
-     *
-     * @param array $data
-     * @param array $classes
-     *
-     * @return array
      */
     public function fit(array $data, array $classes) : array
     {
@@ -93,12 +88,8 @@ class LDA extends EigenTransformerBase
 
     /**
      * Returns unique labels in the dataset
-     *
-     * @param array $classes
-     *
-     * @return array
      */
-    protected function getLabels(array $classes): array
+    protected function getLabels(array $classes) : array
     {
         $counts = array_count_values($classes);
 
@@ -108,11 +99,6 @@ class LDA extends EigenTransformerBase
     /**
      * Calculates mean of each column for each class and returns
      * n by m matrix where n is number of labels and m is number of columns
-     *
-     * @param array $data
-     * @param array $classes
-     *
-     * @return array
      */
     protected function calculateMeans(array $data, array $classes) : array
     {
@@ -159,13 +145,8 @@ class LDA extends EigenTransformerBase
      * Returns in-class scatter matrix for each class, which
      * is a n by m matrix where n is number of classes and
      * m is number of columns
-     *
-     * @param array $data
-     * @param array $classes
-     *
-     * @return Matrix
      */
-    protected function calculateClassVar($data, $classes)
+    protected function calculateClassVar(array $data, array $classes) : Matrix
     {
         // s is an n (number of classes) by m (number of column) matrix
         $s = array_fill(0, count($data[0]), array_fill(0, count($data[0]), 0));
@@ -187,10 +168,8 @@ class LDA extends EigenTransformerBase
      * Returns between-class scatter matrix for each class, which
      * is an n by m matrix where n is number of classes and
      * m is number of columns
-     *
-     * @return Matrix
      */
-    protected function calculateClassCov()
+    protected function calculateClassCov() : Matrix
     {
         // s is an n (number of classes) by m (number of column) matrix
         $s = array_fill(0, count($this->overallMean), array_fill(0, count($this->overallMean), 0));
@@ -207,13 +186,8 @@ class LDA extends EigenTransformerBase
 
     /**
      * Returns the result of the calculation (x - m)T.(x - m)
-     *
-     * @param array $row
-     * @param array $means
-     *
-     * @return Matrix
      */
-    protected function calculateVar(array $row, array $means)
+    protected function calculateVar(array $row, array $means) : Matrix
     {
         $x = new Matrix($row, false);
         $m = new Matrix($means, false);
@@ -226,13 +200,9 @@ class LDA extends EigenTransformerBase
      * Transforms the given sample to a lower dimensional vector by using
      * the eigenVectors obtained in the last run of <code>fit</code>.
      *
-     * @param array $sample
-     *
-     * @return array
-     *
      * @throws \Exception
      */
-    public function transform(array $sample)
+    public function transform(array $sample) : array
     {
         if (!$this->fit) {
             throw new \Exception('LDA has not been fitted with respect to original dataset, please run LDA::fit() first');

src/Phpml/DimensionReduction/PCA.php

@@ -32,7 +32,7 @@ class PCA extends EigenTransformerBase
      *
      * @throws \Exception
      */
-    public function __construct($totalVariance = null, $numFeatures = null)
+    public function __construct(float $totalVariance = null, int $numFeatures = null)
     {
         if ($totalVariance !== null && ($totalVariance < 0.1 || $totalVariance > 0.99)) {
             throw new \Exception('Total variance can be a value between 0.1 and 0.99');
@@ -57,12 +57,8 @@ class PCA extends EigenTransformerBase
      * of this data while preserving $totalVariance or $numFeatures. <br>
      * $data is an n-by-m matrix and returned array is
      * n-by-k matrix where k <= m
-     *
-     * @param array $data
-     *
-     * @return array
      */
-    public function fit(array $data)
+    public function fit(array $data) : array
     {
         $n = count($data[0]);
 
@@ -77,10 +73,6 @@ class PCA extends EigenTransformerBase
         return $this->reduce($data);
     }
 
-    /**
-     * @param array $data
-     * @param int   $n
-     */
     protected function calculateMeans(array $data, int $n)
     {
         // Calculate means for each dimension
@@ -94,13 +86,8 @@ class PCA extends EigenTransformerBase
     /**
      * Normalization of the data includes subtracting mean from
      * each dimension therefore dimensions will be centered to zero
-     *
-     * @param array $data
-     * @param int   $n
-     *
-     * @return array
      */
-    protected function normalize(array $data, int $n)
+    protected function normalize(array $data, int $n) : array
     {
         if (empty($this->means)) {
             $this->calculateMeans($data, $n);
@@ -120,13 +107,9 @@ class PCA extends EigenTransformerBase
      * Transforms the given sample to a lower dimensional vector by using
      * the eigenVectors obtained in the last run of <code>fit</code>.
      *
-     * @param array $sample
-     *
-     * @return array
-     *
      * @throws \Exception
      */
-    public function transform(array $sample)
+    public function transform(array $sample) : array
     {
         if (!$this->fit) {
             throw new \Exception('PCA has not been fitted with respect to original dataset, please run PCA::fit() first');

src/Phpml/Exception/DatasetException.php

@@ -6,12 +6,7 @@ namespace Phpml\Exception;
 
 class DatasetException extends \Exception
 {
-    /**
+    public static function missingFolder(string $path) : DatasetException
-     * @param string $path
-     *
-     * @return DatasetException
-     */
-    public static function missingFolder(string $path)
     {
         return new self(sprintf('Dataset root folder "%s" missing.', $path));
     }

src/Phpml/Exception/FileException.php

@@ -6,32 +6,17 @@ namespace Phpml\Exception;
 
 class FileException extends \Exception
 {
-    /**
+    public static function missingFile(string $filepath) : FileException
-     * @param string $filepath
-     *
-     * @return FileException
-     */
-    public static function missingFile(string $filepath)
     {
         return new self(sprintf('File "%s" missing.', $filepath));
     }
 
-    /**
+    public static function cantOpenFile(string $filepath) : FileException
-     * @param string $filepath
-     *
-     * @return FileException
-     */
-    public static function cantOpenFile(string $filepath)
     {
         return new self(sprintf('File "%s" can\'t be open.', $filepath));
     }
 
-    /**
+    public static function cantSaveFile(string $filepath) : FileException
-     * @param string $filepath
-     *
-     * @return FileException
-     */
-    public static function cantSaveFile(string $filepath)
     {
         return new self(sprintf('File "%s" can\'t be saved.', $filepath));
     }

src/Phpml/Exception/InvalidArgumentException.php

@@ -6,164 +6,95 @@ namespace Phpml\Exception;
 
 class InvalidArgumentException extends \Exception
 {
-    /**
+    public static function arraySizeNotMatch() : InvalidArgumentException
-     * @return InvalidArgumentException
-     */
-    public static function arraySizeNotMatch()
     {
         return new self('Size of given arrays does not match');
     }
 
-    /**
+    public static function percentNotInRange($name) : InvalidArgumentException
-     * @param $name
-     *
-     * @return InvalidArgumentException
-     */
-    public static function percentNotInRange($name)
     {
         return new self(sprintf('%s must be between 0.0 and 1.0', $name));
     }
 
-    /**
+    public static function arrayCantBeEmpty() : InvalidArgumentException
-     * @return InvalidArgumentException
-     */
-    public static function arrayCantBeEmpty()
     {
         return new self('The array has zero elements');
     }
 
-    /**
+    public static function arraySizeToSmall(int $minimumSize = 2) : InvalidArgumentException
-     * @param int $minimumSize
-     *
-     * @return InvalidArgumentException
-     */
-    public static function arraySizeToSmall($minimumSize = 2)
     {
         return new self(sprintf('The array must have at least %d elements', $minimumSize));
     }
 
-    /**
+    public static function matrixDimensionsDidNotMatch() : InvalidArgumentException
-     * @return InvalidArgumentException
-     */
-    public static function matrixDimensionsDidNotMatch()
     {
         return new self('Matrix dimensions did not match');
     }
 
-    /**
+    public static function inconsistentMatrixSupplied() : InvalidArgumentException
-     * @return InvalidArgumentException
-     */
-    public static function inconsistentMatrixSupplied()
     {
         return new self('Inconsistent matrix supplied');
     }
 
-    /**
+    public static function invalidClustersNumber() : InvalidArgumentException
-     * @return InvalidArgumentException
-     */
-    public static function invalidClustersNumber()
     {
         return new self('Invalid clusters number');
     }
 
     /**
      * @param mixed $target
-     *
-     * @return InvalidArgumentException
      */
-    public static function invalidTarget($target)
+    public static function invalidTarget($target) : InvalidArgumentException
     {
         return new self(sprintf('Target with value "%s" is not part of the accepted classes', $target));
     }
 
-    /**
+    public static function invalidStopWordsLanguage(string $language) : InvalidArgumentException
-     * @param string $language
-     *
-     * @return InvalidArgumentException
-     */
-    public static function invalidStopWordsLanguage(string $language)
     {
         return new self(sprintf('Can\'t find "%s" language for StopWords', $language));
     }
 
-    /**
+    public static function invalidLayerNodeClass() : InvalidArgumentException
-     * @return InvalidArgumentException
-     */
-    public static function invalidLayerNodeClass()
     {
         return new self('Layer node class must implement Node interface');
     }
 
-    /**
+    public static function invalidLayersNumber() : InvalidArgumentException
-     * @return InvalidArgumentException
-     */
-    public static function invalidLayersNumber()
     {
         return new self('Provide at least 1 hidden layer');
     }
 
-    /**
+    public static function invalidClassesNumber() : InvalidArgumentException
-     * @return InvalidArgumentException
-     */
-    public static function invalidClassesNumber()
     {
         return new self('Provide at least 2 different classes');
     }
 
-    /**
+    public static function inconsistentClasses() : InvalidArgumentException
-     * @return InvalidArgumentException
-     */
-    public static function inconsistentClasses()
     {
         return new self('The provided classes don\'t match the classes provided in the constructor');
     }
 
-    /**
+    public static function fileNotFound(string $file) : InvalidArgumentException
-     * @param string $file
-     *
-     * @return InvalidArgumentException
-     */
-    public static function fileNotFound(string $file)
     {
         return new self(sprintf('File "%s" not found', $file));
     }
 
-    /**
+    public static function fileNotExecutable(string $file) : InvalidArgumentException
-     * @param string $file
-     *
-     * @return InvalidArgumentException
-     */
-    public static function fileNotExecutable(string $file)
     {
         return new self(sprintf('File "%s" is not executable', $file));
     }
 
-    /**
+    public static function pathNotFound(string $path) : InvalidArgumentException
-     * @param string $path
-     *
-     * @return InvalidArgumentException
-     */
-    public static function pathNotFound(string $path)
     {
         return new self(sprintf('The specified path "%s" does not exist', $path));
     }
 
-    /**
+    public static function pathNotWritable(string $path) : InvalidArgumentException
-     * @param string $path
-     *
-     * @return InvalidArgumentException
-     */
-    public static function pathNotWritable(string $path)
     {
         return new self(sprintf('The specified path "%s" is not writable', $path));
     }
 
-    /**
+    public static function invalidOperator(string $operator) : InvalidArgumentException
-     * @param string $operator
-     *
-     * @return InvalidArgumentException
-     */
-    public static function invalidOperator(string $operator)
     {
         return new self(sprintf('Invalid operator "%s" provided', $operator));
     }

src/Phpml/Exception/MatrixException.php

@@ -6,26 +6,17 @@ namespace Phpml\Exception;
 
 class MatrixException extends \Exception
 {
-    /**
+    public static function notSquareMatrix() : MatrixException
-     * @return MatrixException
-     */
-    public static function notSquareMatrix()
     {
         return new self('Matrix is not square matrix');
     }
 
-    /**
+    public static function columnOutOfRange() : MatrixException
-     * @return MatrixException
-     */
-    public static function columnOutOfRange()
     {
         return new self('Column out of range');
     }
 
-    /**
+    public static function singularMatrix() : MatrixException
-     * @return MatrixException
-     */
-    public static function singularMatrix()
     {
         return new self('Matrix is singular');
     }

src/Phpml/Exception/NormalizerException.php

@@ -6,10 +6,7 @@ namespace Phpml\Exception;
 
 class NormalizerException extends \Exception
 {
-    /**
+    public static function unknownNorm() : NormalizerException
-     * @return NormalizerException
-     */
-    public static function unknownNorm()
     {
         return new self('Unknown norm supplied.');
     }

src/Phpml/Exception/SerializeException.php

@@ -6,22 +6,12 @@ namespace Phpml\Exception;
 
 class SerializeException extends \Exception
 {
-    /**
+    public static function cantUnserialize(string $filepath)  : SerializeException
-     * @param string $filepath
-     *
-     * @return SerializeException
-     */
-    public static function cantUnserialize(string $filepath)
     {
         return new self(sprintf('"%s" can not be unserialized.', $filepath));
     }
 
-    /**
+    public static function cantSerialize(string $classname)  : SerializeException
-     * @param string $classname
-     *
-     * @return SerializeException
-     */
-    public static function cantSerialize(string $classname)
     {
         return new self(sprintf('Class "%s" can not be serialized.', $classname));
     }

src/Phpml/FeatureExtraction/StopWords.php

@@ -13,32 +13,17 @@ class StopWords
      */
     protected $stopWords;
 
-    /**
-     * @param array $stopWords
-     */
     public function __construct(array $stopWords)
     {
         $this->stopWords = array_fill_keys($stopWords, true);
     }
 
-    /**
+    public function isStopWord(string $token) : bool
-     * @param string $token
-     *
-     * @return bool
-     */
-    public function isStopWord(string $token): bool
     {
         return isset($this->stopWords[$token]);
     }
 
-    /**
+    public static function factory(string $language = 'English') : StopWords
-     * @param string $language
-     *
-     * @return StopWords
-     *
-     * @throws InvalidArgumentException
-     */
-    public static function factory($language = 'English'): StopWords
     {
         $className = __NAMESPACE__."\\StopWords\\$language";
 

src/Phpml/FeatureExtraction/TokenCountVectorizer.php

@@ -34,11 +34,6 @@ class TokenCountVectorizer implements Transformer
      */
     private $frequencies;
 
-    /**
-     * @param Tokenizer $tokenizer
-     * @param StopWords $stopWords
-     * @param float     $minDF
-     */
     public function __construct(Tokenizer $tokenizer, StopWords $stopWords = null, float $minDF = 0.0)
     {
         $this->tokenizer = $tokenizer;
@@ -49,17 +44,11 @@ class TokenCountVectorizer implements Transformer
         $this->frequencies = [];
     }
 
-    /**
-     * @param array $samples
-     */
     public function fit(array $samples)
     {
         $this->buildVocabulary($samples);
     }
 
-    /**
-     * @param array $samples
-     */
     public function transform(array &$samples)
     {
         foreach ($samples as &$sample) {
@@ -69,17 +58,11 @@ class TokenCountVectorizer implements Transformer
         $this->checkDocumentFrequency($samples);
     }
 
-    /**
+    public function getVocabulary() : array
-     * @return array
-     */
-    public function getVocabulary()
     {
         return array_flip($this->vocabulary);
     }
 
-    /**
-     * @param array $samples
-     */
     private function buildVocabulary(array &$samples)
     {
         foreach ($samples as $index => $sample) {
@@ -90,9 +73,6 @@ class TokenCountVectorizer implements Transformer
         }
     }
 
-    /**
-     * @param string $sample
-     */
     private function transformSample(string &$sample)
     {
         $counts = [];
@@ -122,8 +102,6 @@ class TokenCountVectorizer implements Transformer
     }
 
     /**
-     * @param string $token
-     *
      * @return int|bool
      */
     private function getTokenIndex(string $token)
@@ -135,9 +113,6 @@ class TokenCountVectorizer implements Transformer
         return $this->vocabulary[$token] ?? false;
     }
 
-    /**
-     * @param string $token
-     */
     private function addTokenToVocabulary(string $token)
     {
         if ($this->isStopWord($token)) {
@@ -149,19 +124,11 @@ class TokenCountVectorizer implements Transformer
         }
     }
 
-    /**
-     * @param string $token
-     *
-     * @return bool
-     */
     private function isStopWord(string $token): bool
     {
         return $this->stopWords && $this->stopWords->isStopWord($token);
     }
 
-    /**
-     * @param string $token
-     */
     private function updateFrequency(string $token)
     {
         if (!isset($this->frequencies[$token])) {
@@ -171,9 +138,6 @@ class TokenCountVectorizer implements Transformer
         ++$this->frequencies[$token];
     }
 
-    /**
-     * @param array $samples
-     */
     private function checkDocumentFrequency(array &$samples)
     {
         if ($this->minDF > 0) {
@@ -184,10 +148,6 @@ class TokenCountVectorizer implements Transformer
         }
     }
 
-    /**
-     * @param array $sample
-     * @param array $beyondMinimum
-     */
     private function resetBeyondMinimum(array &$sample, array $beyondMinimum)
     {
         foreach ($beyondMinimum as $index) {
@@ -195,12 +155,7 @@ class TokenCountVectorizer implements Transformer
         }
     }
 
-    /**
+    private function getBeyondMinimumIndexes(int $samplesCount) : array
-     * @param int $samplesCount
-     *
-     * @return array
-     */
-    private function getBeyondMinimumIndexes(int $samplesCount)
     {
         $indexes = [];
         foreach ($this->frequencies as $token => $frequency) {

src/Phpml/Helper/OneVsRest.php

@@ -27,9 +27,6 @@ trait OneVsRest
 
     /**
      * Train a binary classifier in the OvR style
-     *
-     * @param array $samples
-     * @param array $targets
      */
     public function train(array $samples, array $targets)
     {
@@ -39,13 +36,6 @@ trait OneVsRest
         $this->trainBylabel($samples, $targets);
     }
 
-    /**
-     * @param array $samples
-     * @param array $targets
-     * @param array $allLabels All training set labels
-     *
-     * @return void
-     */
     protected function trainByLabel(array $samples, array $targets, array $allLabels = [])
     {
         // Overwrites the current value if it exist. $allLabels must be provided for each partialTrain run.
@@ -122,12 +112,11 @@ trait OneVsRest
      * $targets is not passed by reference nor contains objects so this method
      * changes will not affect the caller $targets array.
      *
-     * @param array $targets
      * @param mixed $label
      *
      * @return array Binarized targets and target's labels
      */
-    private function binarizeTargets($targets, $label)
+    private function binarizeTargets(array $targets, $label) : array
     {
         $notLabel = "not_$label";
         foreach ($targets as $key => $target) {
@@ -140,8 +129,6 @@ trait OneVsRest
     }
 
     /**
-     * @param array $sample
-     *
      * @return mixed
      */
     protected function predictSample(array $sample)
@@ -163,10 +150,6 @@ trait OneVsRest
 
     /**
      * Each classifier should implement this method instead of train(samples, targets)
-     *
-     * @param array $samples
-     * @param array $targets
-     * @param array $labels
      */
     abstract protected function trainBinary(array $samples, array $targets, array $labels);
 
@@ -181,9 +164,6 @@ trait OneVsRest
      * Each classifier that make use of OvR approach should be able to
      * return a probability for a sample to belong to the given label.
      *
-     * @param array  $sample
-     * @param string $label
-     *
      * @return mixed
      */
     abstract protected function predictProbability(array $sample, string $label);
@@ -191,8 +171,6 @@ trait OneVsRest
     /**
      * Each classifier should implement this method instead of predictSample()
      *
-     * @param array $sample
-     *
      * @return mixed
      */
     abstract protected function predictSampleBinary(array $sample);

src/Phpml/Helper/Optimizer/ConjugateGradient.php

@@ -20,11 +20,10 @@ class ConjugateGradient extends GD
     /**
      * @param array    $samples
      * @param array    $targets
-     * @param \Closure $gradientCb
      *
      * @return array
      */
-    public function runOptimization(array $samples, array $targets, \Closure $gradientCb)
+    public function runOptimization(array $samples, array $targets, \Closure $gradientCb) : array
     {
         $this->samples = $samples;
         $this->targets = $targets;
@@ -65,12 +64,8 @@ class ConjugateGradient extends GD
     /**
      * Executes the callback function for the problem and returns
      * sum of the gradient for all samples & targets.
-     *
-     * @param array $theta
-     *
-     * @return array
      */
-    protected function gradient(array $theta)
+    protected function gradient(array $theta) : array
     {
         list(, $gradient) = parent::gradient($theta);
 
@@ -79,12 +74,8 @@ class ConjugateGradient extends GD
 
     /**
      * Returns the value of f(x) for given solution
-     *
-     * @param array $theta
-     *
-     * @return float
      */
-    protected function cost(array $theta)
+    protected function cost(array $theta) : float
     {
         list($cost) = parent::gradient($theta);
 
@@ -104,12 +95,8 @@ class ConjugateGradient extends GD
      *  b) Probe a larger alpha (0.01) and calculate cost function
      *		b-1) If cost function decreases, continue enlarging alpha
      *		b-2) If cost function increases, take the midpoint and try again
-     *
-     * @param float $d
-     *
-     * @return float
      */
-    protected function getAlpha(float $d)
+    protected function getAlpha(float $d) : float
     {
         $small = 0.0001 * $d;
         $large = 0.01 * $d;
@@ -153,13 +140,8 @@ class ConjugateGradient extends GD
      * gradient direction.
      *
      * θ(k+1) = θ(k) + α.d
-     *
-     * @param float $alpha
-     * @param array $d
-     *
-     * @return array
      */
-    protected function getNewTheta(float $alpha, array $d)
+    protected function getNewTheta(float $alpha, array $d) : array
     {
         $theta = $this->theta;
 
@@ -187,12 +169,8 @@ class ConjugateGradient extends GD
      *
      * See:
      *  R. Fletcher and C. M. Reeves, "Function minimization by conjugate gradients", Comput. J. 7 (1964), 149–154.
-     *
-     * @param array $newTheta
-     *
-     * @return float
      */
-    protected function getBeta(array $newTheta)
+    protected function getBeta(array $newTheta) : float
     {
         $dNew = array_sum($this->gradient($newTheta));
         $dOld = array_sum($this->gradient($this->theta)) + 1e-100;
@@ -204,14 +182,8 @@ class ConjugateGradient extends GD
      * Calculates the new conjugate direction
      *
      * d(k+1) =–∇f(x(k+1)) + β(k).d(k)
-     *
-     * @param array $theta
-     * @param float $beta
-     * @param array $d
-     *
-     * @return array
      */
-    protected function getNewDirection(array $theta, float $beta, array $d)
+    protected function getNewDirection(array $theta, float $beta, array $d) : array
     {
         $grad = $this->gradient($theta);
 
@@ -227,13 +199,8 @@ class mp
 {
     /**
      * Element-wise <b>multiplication</b> of two vectors of the same size
-     *
-     * @param array $m1
-     * @param array $m2
-     *
-     * @return array
      */
-    public static function mul(array $m1, array $m2)
+    public static function mul(array $m1, array $m2) : array
     {
         $res = [];
         foreach ($m1 as $i => $val) {
@@ -245,13 +212,8 @@ class mp
 
     /**
      * Element-wise <b>division</b> of two vectors of the same size
-     *
-     * @param array $m1
-     * @param array $m2
-     *
-     * @return array
      */
-    public static function div(array $m1, array $m2)
+    public static function div(array $m1, array $m2) : array
     {
         $res = [];
         foreach ($m1 as $i => $val) {
@@ -263,14 +225,8 @@ class mp
 
     /**
      * Element-wise <b>addition</b> of two vectors of the same size
-     *
-     * @param array $m1
-     * @param array $m2
-     * @param int   $mag
-     *
-     * @return array
      */
-    public static function add(array $m1, array $m2, int $mag = 1)
+    public static function add(array $m1, array $m2, int $mag = 1) : array
     {
         $res = [];
         foreach ($m1 as $i => $val) {
@@ -282,26 +238,16 @@ class mp
 
     /**
      * Element-wise <b>subtraction</b> of two vectors of the same size
-     *
-     * @param array $m1
-     * @param array $m2
-     *
-     * @return array
      */
-    public static function sub(array $m1, array $m2)
+    public static function sub(array $m1, array $m2) : array
     {
         return self::add($m1, $m2, -1);
     }
 
     /**
      * Element-wise <b>multiplication</b> of a vector with a scalar
-     *
-     * @param array $m1
-     * @param float $m2
-     *
-     * @return array
      */
-    public static function muls(array $m1, float $m2)
+    public static function muls(array $m1, float $m2) : array
     {
         $res = [];
         foreach ($m1 as $val) {
@@ -313,13 +259,8 @@ class mp
 
     /**
      * Element-wise <b>division</b> of a vector with a scalar
-     *
-     * @param array $m1
-     * @param float $m2
-     *
-     * @return array
      */
-    public static function divs(array $m1, float $m2)
+    public static function divs(array $m1, float $m2) : array
     {
         $res = [];
         foreach ($m1 as $val) {
@@ -331,14 +272,8 @@ class mp
 
     /**
      * Element-wise <b>addition</b> of a vector with a scalar
-     *
-     * @param array $m1
-     * @param float $m2
-     * @param int   $mag
-     *
-     * @return array
      */
-    public static function adds(array $m1, float $m2, int $mag = 1)
+    public static function adds(array $m1, float $m2, int $mag = 1) : array
     {
         $res = [];
         foreach ($m1 as $val) {
@@ -350,13 +285,8 @@ class mp
 
     /**
      * Element-wise <b>subtraction</b> of a vector with a scalar
-     *
-     * @param array $m1
-     * @param float $m2
-     *
-     * @return array
      */
-    public static function subs(array $m1, float $m2)
+    public static function subs(array $m1, float $m2) : array
     {
         return self::adds($m1, $m2, -1);
     }

src/Phpml/Helper/Optimizer/GD.php

@@ -17,14 +17,7 @@ class GD extends StochasticGD
      */
     protected $sampleCount = null;
 
-    /**
+    public function runOptimization(array $samples, array $targets, \Closure $gradientCb) : array
-     * @param array    $samples
-     * @param array    $targets
-     * @param \Closure $gradientCb
-     *
-     * @return array
-     */
-    public function runOptimization(array $samples, array $targets, \Closure $gradientCb)
     {
         $this->samples = $samples;
         $this->targets = $targets;
@@ -57,12 +50,8 @@ class GD extends StochasticGD
     /**
      * Calculates gradient, cost function and penalty term for each sample
      * then returns them as an array of values
-     *
-     * @param array $theta
-     *
-     * @return array
      */
-    protected function gradient(array $theta)
+    protected function gradient(array $theta) : array
     {
         $costs = [];
         $gradient = [];
@@ -84,10 +73,6 @@ class GD extends StochasticGD
         return [$costs, $gradient, $totalPenalty];
     }
 
-    /**
-     * @param array $updates
-     * @param float $penalty
-     */
     protected function updateWeightsWithUpdates(array $updates, float $penalty)
     {
         // Updates all weights at once
@@ -110,8 +95,6 @@ class GD extends StochasticGD
 
     /**
      * Clears the optimizer internal vars after the optimization process.
-     *
-     * @return void
      */
     protected function clear()
     {

src/Phpml/Helper/Optimizer/Optimizer.php

@@ -22,8 +22,6 @@ abstract class Optimizer
 
     /**
      * Inits a new instance of Optimizer for the given number of dimensions
-     *
-     * @param int $dimensions
      */
     public function __construct(int $dimensions)
     {
@@ -39,8 +37,6 @@ abstract class Optimizer
     /**
      * Sets the weights manually
      *
-     * @param array $theta
-     *
      * @return $this
      *
      * @throws \Exception
@@ -59,10 +55,6 @@ abstract class Optimizer
     /**
      * Executes the optimization with the given samples & targets
      * and returns the weights
-     *
-     * @param array    $samples
-     * @param array    $targets
-     * @param \Closure $gradientCb
      */
     abstract public function runOptimization(array $samples, array $targets, \Closure $gradientCb);
 }

src/Phpml/Helper/Optimizer/StochasticGD.php

@@ -76,8 +76,6 @@ class StochasticGD extends Optimizer
 
     /**
      * Initializes the SGD optimizer for the given number of dimensions
-     *
-     * @param int $dimensions
      */
     public function __construct(int $dimensions)
     {
@@ -94,8 +92,6 @@ class StochasticGD extends Optimizer
      * If change in the theta is less than given value then the
      * algorithm will stop training
      *
-     * @param float $threshold
-     *
      * @return $this
      */
     public function setChangeThreshold(float $threshold = 1e-5)
@@ -109,8 +105,6 @@ class StochasticGD extends Optimizer
      * Enable/Disable early stopping by checking at each iteration
      * whether changes in theta or cost value are not large enough
      *
-     * @param bool $enable
-     *
      * @return $this
      */
     public function setEarlyStop(bool $enable = true)
@@ -121,8 +115,6 @@ class StochasticGD extends Optimizer
     }
 
     /**
-     * @param float $learningRate
-     *
      * @return $this
      */
     public function setLearningRate(float $learningRate)
@@ -133,8 +125,6 @@ class StochasticGD extends Optimizer
     }
 
     /**
-     * @param int $maxIterations
-     *
      * @return $this
      */
     public function setMaxIterations(int $maxIterations)
@@ -150,14 +140,8 @@ class StochasticGD extends Optimizer
      *
      * The cost function to minimize and the gradient of the function are to be
      * handled by the callback function provided as the third parameter of the method.
-     *
-     * @param array    $samples
-     * @param array    $targets
-     * @param \Closure $gradientCb
-     *
-     * @return array
      */
-    public function runOptimization(array $samples, array $targets, \Closure $gradientCb)
+    public function runOptimization(array $samples, array $targets, \Closure $gradientCb) : array
     {
         $this->samples = $samples;
         $this->targets = $targets;
@@ -197,10 +181,7 @@ class StochasticGD extends Optimizer
         return $this->theta = $bestTheta;
     }
 
-    /**
+    protected function updateTheta() : float
-     * @return float
-     */
-    protected function updateTheta()
     {
         $jValue = 0.0;
         $theta = $this->theta;
@@ -231,12 +212,8 @@ class StochasticGD extends Optimizer
     /**
      * Checks if the optimization is not effective enough and can be stopped
      * in case large enough changes in the solution do not happen
-     *
-     * @param array $oldTheta
-     *
-     * @return boolean
      */
-    protected function earlyStop($oldTheta)
+    protected function earlyStop(array $oldTheta): bool
     {
         // Check for early stop: No change larger than threshold (default 1e-5)
         $diff = array_map(
@@ -263,18 +240,14 @@ class StochasticGD extends Optimizer
     /**
      * Returns the list of cost values for each iteration executed in
      * last run of the optimization
-     *
-     * @return array
      */
-    public function getCostValues()
+    public function getCostValues() : array
     {
         return $this->costValues;
     }
 
     /**
      * Clears the optimizer internal vars after the optimization process.
-     *
-     * @return void
      */
     protected function clear()
     {

src/Phpml/Math/Comparison.php

@@ -9,12 +9,6 @@ use Phpml\Exception\InvalidArgumentException;
 class Comparison
 {
     /**
-     * @param mixed  $a
-     * @param mixed  $b
-     * @param string $operator
-     *
-     * @return bool
-     *
      * @throws InvalidArgumentException
      */
     public static function compare($a, $b, string $operator): bool

src/Phpml/Math/Distance.php

@@ -9,8 +9,6 @@ interface Distance
     /**
      * @param array $a
      * @param array $b
-     *
-     * @return float
      */
-    public function distance(array $a, array $b): float;
+    public function distance(array $a, array $b) : float;
 }

src/Phpml/Math/Distance/Chebyshev.php

@@ -10,14 +10,9 @@ use Phpml\Math\Distance;
 class Chebyshev implements Distance
 {
     /**
-     * @param array $a
-     * @param array $b
-     *
-     * @return float
-     *
      * @throws InvalidArgumentException
      */
-    public function distance(array $a, array $b): float
+    public function distance(array $a, array $b) : float
     {
         if (count($a) !== count($b)) {
             throw InvalidArgumentException::arraySizeNotMatch();

src/Phpml/Math/Distance/Euclidean.php

@@ -10,14 +10,9 @@ use Phpml\Math\Distance;
 class Euclidean implements Distance
 {
     /**
-     * @param array $a
-     * @param array $b
-     *
-     * @return float
-     *
      * @throws InvalidArgumentException
      */
-    public function distance(array $a, array $b): float
+    public function distance(array $a, array $b) : float
     {
         if (count($a) !== count($b)) {
             throw InvalidArgumentException::arraySizeNotMatch();
@@ -34,13 +29,8 @@ class Euclidean implements Distance
 
     /**
      * Square of Euclidean distance
-     *
-     * @param array $a
-     * @param array $b
-     *
-     * @return float
      */
-    public function sqDistance(array $a, array $b): float
+    public function sqDistance(array $a, array $b) : float
     {
         return $this->distance($a, $b) ** 2;
     }

src/Phpml/Math/Distance/Manhattan.php

@@ -10,14 +10,9 @@ use Phpml\Math\Distance;
 class Manhattan implements Distance
 {
     /**
-     * @param array $a
-     * @param array $b
-     *
-     * @return float
-     *
      * @throws InvalidArgumentException
      */
-    public function distance(array $a, array $b): float
+    public function distance(array $a, array $b) : float
     {
         if (count($a) !== count($b)) {
             throw InvalidArgumentException::arraySizeNotMatch();

src/Phpml/Math/Distance/Minkowski.php

@@ -14,23 +14,15 @@ class Minkowski implements Distance
      */
     private $lambda;
 
-    /**
-     * @param float $lambda
-     */
     public function __construct(float $lambda = 3.0)
     {
         $this->lambda = $lambda;
     }
 
     /**
-     * @param array $a
-     * @param array $b
-     *
-     * @return float
-     *
      * @throws InvalidArgumentException
      */
-    public function distance(array $a, array $b): float
+    public function distance(array $a, array $b) : float
     {
         if (count($a) !== count($b)) {
             throw InvalidArgumentException::arraySizeNotMatch();

src/Phpml/Math/Kernel/RBF.php

@@ -14,9 +14,6 @@ class RBF implements Kernel
      */
     private $gamma;
 
-    /**
-     * @param float $gamma
-     */
     public function __construct(float $gamma)
     {
         $this->gamma = $gamma;
@@ -25,8 +22,6 @@ class RBF implements Kernel
     /**
      * @param array $a
      * @param array $b
-     *
-     * @return float
      */
     public function compute($a, $b)
     {

src/Phpml/Math/LinearAlgebra/EigenvalueDecomposition.php

@@ -835,7 +835,6 @@ class EigenvalueDecomposition
     /**
      * Return the eigenvector matrix
      *
-     *
      * @return array
      */
     public function getEigenvectors()

src/Phpml/Math/LinearAlgebra/LUDecomposition.php

@@ -30,8 +30,8 @@ declare(strict_types=1);
 
 namespace Phpml\Math\LinearAlgebra;
 
-use Phpml\Math\Matrix;
 use Phpml\Exception\MatrixException;
+use Phpml\Math\Matrix;
 
 class LUDecomposition
 {
@@ -142,7 +142,7 @@ class LUDecomposition
      *
      * @return Matrix Lower triangular factor
      */
-    public function getL()
+    public function getL() : Matrix
     {
         $L = [];
         for ($i = 0; $i < $this->m; ++$i) {
@@ -165,7 +165,7 @@ class LUDecomposition
      *
      * @return Matrix Upper triangular factor
      */
-    public function getU()
+    public function getU() : Matrix
     {
         $U = [];
         for ($i = 0; $i < $this->n; ++$i) {
@@ -186,7 +186,7 @@ class LUDecomposition
      *
      * @return array Pivot vector
      */
-    public function getPivot()
+    public function getPivot() : array
     {
         return $this->piv;
     }
@@ -247,7 +247,7 @@ class LUDecomposition
      *
      * @throws MatrixException
      */
-    public function solve(Matrix $B)
+    public function solve(Matrix $B) : array
     {
         if ($B->getRows() != $this->m) {
             throw MatrixException::notSquareMatrix();
@@ -283,15 +283,7 @@ class LUDecomposition
         return $X;
     }
 
-    /**
+    protected function getSubMatrix(array $matrix, array $RL, int $j0, int $jF) : array
-     * @param array $matrix
-     * @param array $RL
-     * @param int   $j0
-     * @param int   $jF
-     *
-     * @return array
-     */
-    protected function getSubMatrix(array $matrix, array $RL, int $j0, int $jF)
     {
         $m = count($RL);
         $n = $jF - $j0;

src/Phpml/Math/Matrix.php

@@ -4,9 +4,9 @@ declare(strict_types=1);
 
 namespace Phpml\Math;
 
-use Phpml\Math\LinearAlgebra\LUDecomposition;
 use Phpml\Exception\InvalidArgumentException;
 use Phpml\Exception\MatrixException;
+use Phpml\Math\LinearAlgebra\LUDecomposition;
 
 class Matrix
 {
@@ -31,9 +31,6 @@ class Matrix
     private $determinant;
 
     /**
-     * @param array $matrix
-     * @param bool  $validate
-     *
      * @throws InvalidArgumentException
      */
     public function __construct(array $matrix, bool $validate = true)
@@ -59,12 +56,7 @@ class Matrix
         $this->matrix = $matrix;
     }
 
-    /**
+    public static function fromFlatArray(array $array) : Matrix
-     * @param array $array
-     *
-     * @return Matrix
-     */
-    public static function fromFlatArray(array $array)
     {
         $matrix = [];
         foreach ($array as $value) {
@@ -74,46 +66,30 @@ class Matrix
         return new self($matrix);
     }
 
-    /**
+    public function toArray() : array
-     * @return array
-     */
-    public function toArray()
     {
         return $this->matrix;
     }
 
-    /**
+    public function toScalar() : float
-     * @return float
-     */
-    public function toScalar()
     {
         return $this->matrix[0][0];
     }
 
-    /**
+    public function getRows(): int
-     * @return int
-     */
-    public function getRows()
     {
         return $this->rows;
     }
 
-    /**
+    public function getColumns(): int
-     * @return int
-     */
-    public function getColumns()
     {
         return $this->columns;
     }
 
     /**
-     * @param $column
-     *
-     * @return array
-     *
      * @throws MatrixException
      */
-    public function getColumnValues($column)
+    public function getColumnValues($column) : array
     {
         if ($column >= $this->columns) {
             throw MatrixException::columnOutOfRange();
@@ -142,18 +118,12 @@ class Matrix
         return $this->determinant = $lu->det();
     }
 
-    /**
+    public function isSquare(): bool
-     * @return bool
-     */
-    public function isSquare()
     {
         return $this->columns === $this->rows;
     }
 
-    /**
+    public function transpose() : Matrix
-     * @return Matrix
-     */
-    public function transpose()
     {
         if ($this->rows == 1) {
             $matrix = array_map(function ($el) {
@@ -166,14 +136,7 @@ class Matrix
         return new self($matrix, false);
     }
 
-    /**
+    public function multiply(Matrix $matrix) : Matrix
-     * @param Matrix $matrix
-     *
-     * @return Matrix
-     *
-     * @throws InvalidArgumentException
-     */
-    public function multiply(Matrix $matrix)
     {
         if ($this->columns != $matrix->getRows()) {
             throw InvalidArgumentException::inconsistentMatrixSupplied();
@@ -194,12 +157,7 @@ class Matrix
         return new self($product, false);
     }
 
-    /**
+    public function divideByScalar($value) : Matrix
-     * @param $value
-     *
-     * @return Matrix
-     */
-    public function divideByScalar($value)
     {
         $newMatrix = [];
         for ($i = 0; $i < $this->rows; ++$i) {
@@ -211,12 +169,7 @@ class Matrix
         return new self($newMatrix, false);
     }
 
-    /**
+    public function multiplyByScalar($value) : Matrix
-     * @param $value
-     *
-     * @return Matrix
-     */
-    public function multiplyByScalar($value)
     {
         $newMatrix = [];
         for ($i = 0; $i < $this->rows; ++$i) {
@@ -230,37 +183,24 @@ class Matrix
 
     /**
      * Element-wise addition of the matrix with another one
-     *
-     * @param Matrix $other
-     *
-     * @return Matrix
      */
-    public function add(Matrix $other)
+    public function add(Matrix $other) : Matrix
     {
         return $this->_add($other);
     }
 
     /**
      * Element-wise subtracting of another matrix from this one
-     *
-     * @param Matrix $other
-     *
-     * @return Matrix
      */
-    public function subtract(Matrix $other)
+    public function subtract(Matrix $other) : Matrix
     {
         return $this->_add($other, -1);
     }
 
     /**
      * Element-wise addition or substraction depending on the given sign parameter
-     *
-     * @param Matrix $other
-     * @param int    $sign
-     *
-     * @return Matrix
      */
-    protected function _add(Matrix $other, $sign = 1)
+    protected function _add(Matrix $other, int $sign = 1) : Matrix
     {
         $a1 = $this->toArray();
         $a2 = $other->toArray();
@@ -275,12 +215,7 @@ class Matrix
         return new self($newMatrix, false);
     }
 
-    /**
+    public function inverse() : Matrix
-     * @return Matrix
-     *
-     * @throws MatrixException
-     */
-    public function inverse()
     {
         if (!$this->isSquare()) {
             throw MatrixException::notSquareMatrix();
@@ -295,10 +230,8 @@ class Matrix
 
     /**
      * Returns diagonal identity matrix of the same size of this matrix
-     *
-     * @return Matrix
      */
-    protected function getIdentity()
+    protected function getIdentity() : Matrix
     {
         $array = array_fill(0, $this->rows, array_fill(0, $this->columns, 0));
         for ($i = 0; $i < $this->rows; ++$i) {
@@ -308,13 +241,7 @@ class Matrix
         return new self($array, false);
     }
 
-    /**
+    public function crossOut(int $row, int $column) : Matrix
-     * @param int $row
-     * @param int $column
-     *
-     * @return Matrix
-     */
-    public function crossOut(int $row, int $column)
     {
         $newMatrix = [];
         $r = 0;
@@ -334,9 +261,6 @@ class Matrix
         return new self($newMatrix, false);
     }
 
-    /**
-     * @return bool
-     */
     public function isSingular() : bool
     {
         return 0 == $this->getDeterminant();
@@ -344,12 +268,8 @@ class Matrix
 
     /**
      * Returns the transpose of given array
-     *
-     * @param array $array
-     *
-     * @return array
      */
-    public static function transposeArray(array $array)
+    public static function transposeArray(array $array) : array
     {
         return (new self($array, false))->transpose()->toArray();
     }
@@ -357,13 +277,8 @@ class Matrix
     /**
      * Returns the dot product of two arrays<br>
      * Matrix::dot(x, y) ==> x.y'
-     *
-     * @param array $array1
-     * @param array $array2
-     *
-     * @return array
      */
-    public static function dot(array $array1, array $array2)
+    public static function dot(array $array1, array $array2) : array
     {
         $m1 = new self($array1, false);
         $m2 = new self($array2, false);

src/Phpml/Math/Set.php

@@ -21,11 +21,6 @@ class Set implements \IteratorAggregate
 
     /**
      * Creates the union of A and B.
-     *
-     * @param Set $a
-     * @param Set $b
-     *
-     * @return Set
      */
     public static function union(Set $a, Set $b) : Set
     {
@@ -34,11 +29,6 @@ class Set implements \IteratorAggregate
 
     /**
      * Creates the intersection of A and B.
-     *
-     * @param Set $a
-     * @param Set $b
-     *
-     * @return Set
      */
     public static function intersection(Set $a, Set $b) : Set
     {
@@ -47,11 +37,6 @@ class Set implements \IteratorAggregate
 
     /**
      * Creates the difference of A and B.
-     *
-     * @param Set $a
-     * @param Set $b
-     *
-     * @return Set
      */
     public static function difference(Set $a, Set $b) : Set
     {
@@ -61,9 +46,6 @@ class Set implements \IteratorAggregate
     /**
      * Creates the Cartesian product of A and B.
      *
-     * @param Set $a
-     * @param Set $b
-     *
      * @return Set[]
      */
     public static function cartesian(Set $a, Set $b) : array
@@ -82,8 +64,6 @@ class Set implements \IteratorAggregate
     /**
      * Creates the power set of A.
      *
-     * @param Set $a
-     *
      * @return Set[]
      */
     public static function power(Set $a) : array
@@ -115,8 +95,6 @@ class Set implements \IteratorAggregate
 
     /**
      * @param string|int|float $element
-     *
-     * @return Set
      */
     public function add($element) : Set
     {
@@ -125,8 +103,6 @@ class Set implements \IteratorAggregate
 
     /**
      * @param string[]|int[]|float[] $elements
-     *
-     * @return Set
      */
     public function addAll(array $elements) : Set
     {
@@ -137,8 +113,6 @@ class Set implements \IteratorAggregate
 
     /**
      * @param string|int|float $element
-     *
-     * @return Set
      */
     public function remove($element) : Set
     {
@@ -147,8 +121,6 @@ class Set implements \IteratorAggregate
 
     /**
      * @param string[]|int[]|float[] $elements
-     *
-     * @return Set
      */
     public function removeAll(array $elements) : Set
     {
@@ -159,8 +131,6 @@ class Set implements \IteratorAggregate
 
     /**
      * @param string|int|float $element
-     *
-     * @return bool
      */
     public function contains($element) : bool
     {
@@ -169,8 +139,6 @@ class Set implements \IteratorAggregate
 
     /**
      * @param string[]|int[]|float[] $elements
-     *
-     * @return bool
      */
     public function containsAll(array $elements) : bool
     {
@@ -185,25 +153,16 @@ class Set implements \IteratorAggregate
         return $this->elements;
     }
 
-    /**
-     * @return \ArrayIterator
-     */
     public function getIterator() : \ArrayIterator
     {
         return new \ArrayIterator($this->elements);
     }
 
-    /**
-     * @return bool
-     */
     public function isEmpty() : bool
     {
         return $this->cardinality() == 0;
     }
 
-    /**
-     * @return int
-     */
     public function cardinality() : int
     {
         return count($this->elements);

src/Phpml/Math/Statistic/Correlation.php

@@ -12,11 +12,9 @@ class Correlation
      * @param array|int[]|float[] $x
      * @param array|int[]|float[] $y
      *
-     * @return float
-     *
      * @throws InvalidArgumentException
      */
-    public static function pearson(array $x, array $y)
+    public static function pearson(array $x, array $y) : float
     {
         if (count($x) !== count($y)) {
             throw InvalidArgumentException::arraySizeNotMatch();

src/Phpml/Math/Statistic/Covariance.php

@@ -11,17 +11,9 @@ class Covariance
     /**
      * Calculates covariance from two given arrays, x and y, respectively
      *
-     * @param array $x
-     * @param array $y
-     * @param bool  $sample
-     * @param float $meanX
-     * @param float $meanY
-     *
-     * @return float
-     *
      * @throws InvalidArgumentException
      */
-    public static function fromXYArrays(array $x, array $y, $sample = true, float $meanX = null, float $meanY = null)
+    public static function fromXYArrays(array $x, array $y, bool $sample = true, float $meanX = null, float $meanY = null) : float
     {
         if (empty($x) || empty($y)) {
             throw InvalidArgumentException::arrayCantBeEmpty();
@@ -56,19 +48,10 @@ class Covariance
     /**
      * Calculates covariance of two dimensions, i and k in the given data.
      *
-     * @param array $data
-     * @param int   $i
-     * @param int   $k
-     * @param bool  $sample
-     * @param float $meanX
-     * @param float $meanY
-     *
-     * @return float
-     *
      * @throws InvalidArgumentException
      * @throws \Exception
      */
-    public static function fromDataset(array $data, int $i, int $k, bool $sample = true, float $meanX = null, float $meanY = null)
+    public static function fromDataset(array $data, int $i, int $k, bool $sample = true, float $meanX = null, float $meanY = null) : float
     {
         if (empty($data)) {
             throw InvalidArgumentException::arrayCantBeEmpty();
@@ -127,12 +110,9 @@ class Covariance
     /**
      * Returns the covariance matrix of n-dimensional data
      *
-     * @param array      $data
      * @param array|null $means
-     *
-     * @return array
      */
-    public static function covarianceMatrix(array $data, array $means = null)
+    public static function covarianceMatrix(array $data, array $means = null) : array
     {
         $n = count($data[0]);
 

src/Phpml/Math/Statistic/Gaussian.php

@@ -16,10 +16,6 @@ class Gaussian
      */
     protected $std;
 
-    /**
-     * @param float $mean
-     * @param float $std
-     */
     public function __construct(float $mean, float $std)
     {
         $this->mean = $mean;
@@ -29,8 +25,6 @@ class Gaussian
     /**
      * Returns probability density of the given <i>$value</i>
      *
-     * @param float $value
-     *
      * @return float|int
      */
     public function pdf(float $value)
@@ -46,14 +40,8 @@ class Gaussian
     /**
      * Returns probability density value of the given <i>$value</i> based on
      * given standard deviation and the mean
-     *
-     * @param float $mean
-     * @param float $std
-     * @param float $value
-     *
-     * @return float
      */
-    public static function distributionPdf(float $mean, float $std, float $value)
+    public static function distributionPdf(float $mean, float $std, float $value) : float
     {
         $normal = new self($mean, $std);
 

src/Phpml/Math/Statistic/Mean.php

@@ -11,11 +11,9 @@ class Mean
     /**
      * @param array $numbers
      *
-     * @return float
-     *
      * @throws InvalidArgumentException
      */
-    public static function arithmetic(array $numbers)
+    public static function arithmetic(array $numbers) : float
     {
         self::checkArrayLength($numbers);
 

src/Phpml/Math/Statistic/StandardDeviation.php

@@ -10,13 +10,10 @@ class StandardDeviation
 {
     /**
      * @param array|float[] $a
-     * @param bool          $sample
-     *
-     * @return float
      *
      * @throws InvalidArgumentException
      */
-    public static function population(array $a, $sample = true)
+    public static function population(array $a, bool $sample = true) : float
     {
         if (empty($a)) {
             throw InvalidArgumentException::arrayCantBeEmpty();

src/Phpml/Metric/ClassificationReport.php

@@ -31,10 +31,6 @@ class ClassificationReport
      */
     private $average = [];
 
-    /**
-     * @param array $actualLabels
-     * @param array $predictedLabels
-     */
     public function __construct(array $actualLabels, array $predictedLabels)
     {
         $truePositive = $falsePositive = $falseNegative = $this->support = self::getLabelIndexedArray($actualLabels, $predictedLabels);
@@ -55,51 +51,31 @@ class ClassificationReport
         $this->computeAverage();
     }
 
-    /**
+    public function getPrecision() : array
-     * @return array
-     */
-    public function getPrecision()
     {
         return $this->precision;
     }
 
-    /**
+    public function getRecall() : array
-     * @return array
-     */
-    public function getRecall()
     {
         return $this->recall;
     }
 
-    /**
+    public function getF1score() : array
-     * @return array
-     */
-    public function getF1score()
     {
         return $this->f1score;
     }
 
-    /**
+    public function getSupport() : array
-     * @return array
-     */
-    public function getSupport()
     {
         return $this->support;
     }
 
-    /**
+    public function getAverage() : array
-     * @return array
-     */
-    public function getAverage()
     {
         return $this->average;
     }
 
-    /**
-     * @param array $truePositive
-     * @param array $falsePositive
-     * @param array $falseNegative
-     */
     private function computeMetrics(array $truePositive, array $falsePositive, array $falseNegative)
     {
         foreach ($truePositive as $label => $tp) {
@@ -122,9 +98,6 @@ class ClassificationReport
     }
 
     /**
-     * @param int $truePositive
-     * @param int $falsePositive
-     *
      * @return float|string
      */
     private function computePrecision(int $truePositive, int $falsePositive)
@@ -137,9 +110,6 @@ class ClassificationReport
     }
 
     /**
-     * @param int $truePositive
-     * @param int $falseNegative
-     *
      * @return float|string
      */
     private function computeRecall(int $truePositive, int $falseNegative)
@@ -151,13 +121,7 @@ class ClassificationReport
         return $truePositive / $divider;
     }
 
-    /**
+    private function computeF1Score(float $precision, float $recall) : float
-     * @param float $precision
-     * @param float $recall
-     *
-     * @return float
-     */
-    private function computeF1Score(float $precision, float $recall): float
     {
         if (0 == ($divider = $precision + $recall)) {
             return 0.0;
@@ -172,7 +136,7 @@ class ClassificationReport
      *
      * @return array
      */
-    private static function getLabelIndexedArray(array $actualLabels, array $predictedLabels): array
+    private static function getLabelIndexedArray(array $actualLabels, array $predictedLabels) : array
     {
         $labels = array_values(array_unique(array_merge($actualLabels, $predictedLabels)));
         sort($labels);

src/Phpml/Metric/ConfusionMatrix.php

@@ -13,7 +13,7 @@ class ConfusionMatrix
      *
      * @return array
      */
-    public static function compute(array $actualLabels, array $predictedLabels, array $labels = null): array
+    public static function compute(array $actualLabels, array $predictedLabels, array $labels = null) : array
     {
         $labels = $labels ? array_flip($labels) : self::getUniqueLabels($actualLabels);
         $matrix = self::generateMatrixWithZeros($labels);
@@ -43,7 +43,7 @@ class ConfusionMatrix
      *
      * @return array
      */
-    private static function generateMatrixWithZeros(array $labels): array
+    private static function generateMatrixWithZeros(array $labels) : array
     {
         $count = count($labels);
         $matrix = [];
@@ -60,7 +60,7 @@ class ConfusionMatrix
      *
      * @return array
      */
-    private static function getUniqueLabels(array $labels): array
+    private static function getUniqueLabels(array $labels) : array
     {
         $labels = array_values(array_unique($labels));
         sort($labels);

src/Phpml/ModelManager.php

@@ -4,18 +4,11 @@ declare(strict_types=1);
 
 namespace Phpml;
 
-use Phpml\Exception\SerializeException;
 use Phpml\Exception\FileException;
+use Phpml\Exception\SerializeException;
 
 class ModelManager
 {
-    /**
-     * @param Estimator $estimator
-     * @param string    $filepath
-     *
-     * @throws FileException
-     * @throws SerializeException
-     */
     public function saveToFile(Estimator $estimator, string $filepath)
     {
         if (!is_writable(dirname($filepath))) {
@@ -33,14 +26,6 @@ class ModelManager
         }
     }
 
-    /**
-     * @param string $filepath
-     *
-     * @return Estimator
-     *
-     * @throws FileException
-     * @throws SerializeException
-     */
     public function restoreFromFile(string $filepath) : Estimator
     {
         if (!file_exists($filepath) || !is_readable($filepath)) {

src/Phpml/NeuralNetwork/ActivationFunction.php

@@ -8,8 +8,6 @@ interface ActivationFunction
 {
     /**
      * @param float|int $value
-     *
-     * @return float
      */
-    public function compute($value): float;
+    public function compute($value) : float;
 }

src/Phpml/NeuralNetwork/ActivationFunction/BinaryStep.php

@@ -10,10 +10,8 @@ class BinaryStep implements ActivationFunction
 {
     /**
      * @param float|int $value
-     *
-     * @return float
      */
-    public function compute($value): float
+    public function compute($value) : float
     {
         return $value >= 0 ? 1.0 : 0.0;
     }

src/Phpml/NeuralNetwork/ActivationFunction/Gaussian.php

@@ -10,10 +10,8 @@ class Gaussian implements ActivationFunction
 {
     /**
      * @param float|int $value
-     *
-     * @return float
      */
-    public function compute($value): float
+    public function compute($value) : float
     {
         return exp(-pow($value, 2));
     }

src/Phpml/NeuralNetwork/ActivationFunction/HyperbolicTangent.php

@@ -13,20 +13,15 @@ class HyperbolicTangent implements ActivationFunction
      */
     private $beta;
 
-    /**
+    public function __construct(float $beta = 1.0)
-     * @param float $beta
-     */
-    public function __construct($beta = 1.0)
     {
         $this->beta = $beta;
     }
 
     /**
      * @param float|int $value
-     *
-     * @return float
      */
-    public function compute($value): float
+    public function compute($value) : float
     {
         return tanh($this->beta * $value);
     }

src/Phpml/NeuralNetwork/ActivationFunction/PReLU.php

@@ -13,20 +13,15 @@ class PReLU implements ActivationFunction
      */
     private $beta;
 
-    /**
+    public function __construct(float $beta = 0.01)
-     * @param float $beta
-     */
-    public function __construct($beta = 0.01)
     {
         $this->beta = $beta;
     }
 
     /**
      * @param float|int $value
-     *
-     * @return float
      */
-    public function compute($value): float
+    public function compute($value) : float
     {
         return $value >= 0 ? $value : $this->beta * $value;
     }

src/Phpml/NeuralNetwork/ActivationFunction/Sigmoid.php

@@ -13,20 +13,15 @@ class Sigmoid implements ActivationFunction
      */
     private $beta;
 
-    /**
+    public function __construct(float $beta = 1.0)
-     * @param float $beta
-     */
-    public function __construct($beta = 1.0)
     {
         $this->beta = $beta;
     }
 
     /**
      * @param float|int $value
-     *
-     * @return float
      */
-    public function compute($value): float
+    public function compute($value) : float
     {
         return 1 / (1 + exp(-$this->beta * $value));
     }

src/Phpml/NeuralNetwork/ActivationFunction/ThresholdedReLU.php

@@ -13,20 +13,15 @@ class ThresholdedReLU implements ActivationFunction
      */
     private $theta;
 
-    /**
+    public function __construct(float $theta = 1.0)
-     * @param float $theta
-     */
-    public function __construct($theta = 1.0)
     {
         $this->theta = $theta;
     }
 
     /**
      * @param float|int $value
-     *
-     * @return float
      */
-    public function compute($value): float
+    public function compute($value) : float
     {
         return $value > $this->theta ? $value : 0.0;
     }

src/Phpml/NeuralNetwork/Layer.php

@@ -15,10 +15,6 @@ class Layer
     private $nodes = [];
 
     /**
-     * @param int                     $nodesNumber
-     * @param string                  $nodeClass
-     * @param ActivationFunction|null $activationFunction
-     *
      * @throws InvalidArgumentException
      */
     public function __construct(int $nodesNumber = 0, string $nodeClass = Neuron::class, ActivationFunction $activationFunction = null)
@@ -33,7 +29,6 @@ class Layer
     }
 
     /**
-     * @param string                  $nodeClass
      * @param ActivationFunction|null $activationFunction
      *
      * @return Neuron
@@ -47,9 +42,6 @@ class Layer
         return new $nodeClass();
     }
 
-    /**
-     * @param Node $node
-     */
     public function addNode(Node $node)
     {
         $this->nodes[] = $node;
@@ -58,7 +50,7 @@ class Layer
     /**
      * @return Node[]
      */
-    public function getNodes()
+    public function getNodes() : array
     {
         return $this->nodes;
     }

src/Phpml/NeuralNetwork/Network.php

@@ -16,15 +16,12 @@ interface Network
     /**
      * @return array
      */
-    public function getOutput(): array;
+    public function getOutput() : array;
 
-    /**
-     * @param Layer $layer
-     */
     public function addLayer(Layer $layer);
 
     /**
      * @return Layer[]
      */
-    public function getLayers(): array;
+    public function getLayers() : array;
 }

src/Phpml/NeuralNetwork/Network/LayeredNetwork.php

@@ -16,9 +16,6 @@ abstract class LayeredNetwork implements Network
      */
     protected $layers;
 
-    /**
-     * @param Layer $layer
-     */
     public function addLayer(Layer $layer)
     {
         $this->layers[] = $layer;
@@ -27,22 +24,16 @@ abstract class LayeredNetwork implements Network
     /**
      * @return Layer[]
      */
-    public function getLayers(): array
+    public function getLayers() : array
     {
         return $this->layers;
     }
 
-    /**
-     * @return void
-     */
     public function removeLayers()
     {
         unset($this->layers);
     }
 
-    /**
-     * @return Layer
-     */
     public function getOutputLayer(): Layer
     {
         return $this->layers[count($this->layers) - 1];
@@ -51,7 +42,7 @@ abstract class LayeredNetwork implements Network
     /**
      * @return array
      */
-    public function getOutput(): array
+    public function getOutput() : array
     {
         $result = [];
         foreach ($this->getOutputLayer()->getNodes() as $neuron) {

src/Phpml/NeuralNetwork/Network/MultilayerPerceptron.php

@@ -5,16 +5,16 @@ declare(strict_types=1);
 namespace Phpml\NeuralNetwork\Network;
 
 use Phpml\Estimator;
-use Phpml\IncrementalEstimator;
 use Phpml\Exception\InvalidArgumentException;
-use Phpml\NeuralNetwork\Training\Backpropagation;
+use Phpml\Helper\Predictable;
+use Phpml\IncrementalEstimator;
 use Phpml\NeuralNetwork\ActivationFunction;
 use Phpml\NeuralNetwork\Layer;
 use Phpml\NeuralNetwork\Node\Bias;
 use Phpml\NeuralNetwork\Node\Input;
 use Phpml\NeuralNetwork\Node\Neuron;
 use Phpml\NeuralNetwork\Node\Neuron\Synapse;
-use Phpml\Helper\Predictable;
+use Phpml\NeuralNetwork\Training\Backpropagation;
 
 abstract class MultilayerPerceptron extends LayeredNetwork implements Estimator, IncrementalEstimator
 {
@@ -56,13 +56,6 @@ abstract class MultilayerPerceptron extends LayeredNetwork implements Estimator,
     protected $backpropagation = null;
 
     /**
-     * @param int                     $inputLayerFeatures
-     * @param array                   $hiddenLayers
-     * @param array                   $classes
-     * @param int                     $iterations
-     * @param ActivationFunction|null $activationFunction
-     * @param int                     $theta
-     *
      * @throws InvalidArgumentException
      */
     public function __construct(int $inputLayerFeatures, array $hiddenLayers, array $classes, int $iterations = 10000, ActivationFunction $activationFunction = null, int $theta = 1)
@@ -85,9 +78,6 @@ abstract class MultilayerPerceptron extends LayeredNetwork implements Estimator,
         $this->initNetwork();
     }
 
-    /**
-     * @return void
-     */
     private function initNetwork()
     {
         $this->addInputLayer($this->inputLayerFeatures);
@@ -100,10 +90,6 @@ abstract class MultilayerPerceptron extends LayeredNetwork implements Estimator,
         $this->backpropagation = new Backpropagation($this->theta);
     }
 
-    /**
-     * @param array $samples
-     * @param array $targets
-     */
     public function train(array $samples, array $targets)
     {
         $this->reset();
@@ -112,10 +98,6 @@ abstract class MultilayerPerceptron extends LayeredNetwork implements Estimator,
     }
 
     /**
-     * @param array $samples
-     * @param array $targets
-     * @param array $classes
-     *
      * @throws InvalidArgumentException
      */
     public function partialTrain(array $samples, array $targets, array $classes = [])
@@ -131,38 +113,25 @@ abstract class MultilayerPerceptron extends LayeredNetwork implements Estimator,
     }
 
     /**
-     * @param array $sample
      * @param mixed $target
      */
     abstract protected function trainSample(array $sample, $target);
 
     /**
-     * @param array $sample
-     *
      * @return mixed
      */
     abstract protected function predictSample(array $sample);
 
-    /**
-     * @return void
-     */
     protected function reset()
     {
         $this->removeLayers();
     }
 
-    /**
-     * @param int $nodes
-     */
     private function addInputLayer(int $nodes)
     {
         $this->addLayer(new Layer($nodes, Input::class));
     }
 
-    /**
-     * @param array                   $layers
-     * @param ActivationFunction|null $activationFunction
-     */
     private function addNeuronLayers(array $layers, ActivationFunction $activationFunction = null)
     {
         foreach ($layers as $neurons) {
@@ -188,10 +157,6 @@ abstract class MultilayerPerceptron extends LayeredNetwork implements Estimator,
         }
     }
 
-    /**
-     * @param Layer $nextLayer
-     * @param Layer $currentLayer
-     */
     private function generateLayerSynapses(Layer $nextLayer, Layer $currentLayer)
     {
         foreach ($nextLayer->getNodes() as $nextNeuron) {
@@ -201,10 +166,6 @@ abstract class MultilayerPerceptron extends LayeredNetwork implements Estimator,
         }
     }
 
-    /**
-     * @param Layer  $currentLayer
-     * @param Neuron $nextNeuron
-     */
     private function generateNeuronSynapses(Layer $currentLayer, Neuron $nextNeuron)
     {
         foreach ($currentLayer->getNodes() as $currentNeuron) {
@@ -212,10 +173,6 @@ abstract class MultilayerPerceptron extends LayeredNetwork implements Estimator,
         }
     }
 
-    /**
-     * @param array $samples
-     * @param array $targets
-     */
     private function trainSamples(array $samples, array $targets)
     {
         foreach ($targets as $key => $target) {

src/Phpml/NeuralNetwork/Node.php

@@ -6,8 +6,5 @@ namespace Phpml\NeuralNetwork;
 
 interface Node
 {
-    /**
+    public function getOutput() : float;
-     * @return float
-     */
-    public function getOutput(): float;
 }

src/Phpml/NeuralNetwork/Node/Bias.php

@@ -8,10 +8,7 @@ use Phpml\NeuralNetwork\Node;
 
 class Bias implements Node
 {
-    /**
+    public function getOutput() : float
-     * @return float
-     */
-    public function getOutput(): float
     {
         return 1.0;
     }

src/Phpml/NeuralNetwork/Node/Input.php

@@ -13,25 +13,16 @@ class Input implements Node
      */
     private $input;
 
-    /**
-     * @param float $input
-     */
     public function __construct(float $input = 0.0)
     {
         $this->input = $input;
     }
 
-    /**
+    public function getOutput() : float
-     * @return float
-     */
-    public function getOutput(): float
     {
         return $this->input;
     }
 
-    /**
-     * @param float $input
-     */
     public function setInput(float $input)
     {
         $this->input = $input;

src/Phpml/NeuralNetwork/Node/Neuron.php

@@ -5,8 +5,8 @@ declare(strict_types=1);
 namespace Phpml\NeuralNetwork\Node;
 
 use Phpml\NeuralNetwork\ActivationFunction;
-use Phpml\NeuralNetwork\Node\Neuron\Synapse;
 use Phpml\NeuralNetwork\Node;
+use Phpml\NeuralNetwork\Node\Neuron\Synapse;
 
 class Neuron implements Node
 {
@@ -25,9 +25,6 @@ class Neuron implements Node
      */
     protected $output;
 
-    /**
-     * @param ActivationFunction|null $activationFunction
-     */
     public function __construct(ActivationFunction $activationFunction = null)
     {
         $this->activationFunction = $activationFunction ?: new ActivationFunction\Sigmoid();
@@ -35,9 +32,6 @@ class Neuron implements Node
         $this->output = 0;
     }
 
-    /**
-     * @param Synapse $synapse
-     */
     public function addSynapse(Synapse $synapse)
     {
         $this->synapses[] = $synapse;
@@ -51,10 +45,7 @@ class Neuron implements Node
         return $this->synapses;
     }
 
-    /**
+    public function getOutput() : float
-     * @return float
-     */
-    public function getOutput(): float
     {
         if (0 === $this->output) {
             $sum = 0;

src/Phpml/NeuralNetwork/Node/Neuron/Synapse.php

@@ -28,42 +28,27 @@ class Synapse
         $this->weight = $weight ?: $this->generateRandomWeight();
     }
 
-    /**
+    protected function generateRandomWeight() : float
-     * @return float
-     */
-    protected function generateRandomWeight(): float
     {
         return 1 / random_int(5, 25) * (random_int(0, 1) ? -1 : 1);
     }
 
-    /**
+    public function getOutput() : float
-     * @return float
-     */
-    public function getOutput(): float
     {
         return $this->weight * $this->node->getOutput();
     }
 
-    /**
+    public function changeWeight(float $delta)
-     * @param float $delta
-     */
-    public function changeWeight($delta)
     {
         $this->weight += $delta;
     }
 
-    /**
+    public function getWeight() : float
-     * @return float
-     */
-    public function getWeight()
     {
         return $this->weight;
     }
 
-    /**
+    public function getNode(): Node
-     * @return Node
-     */
-    public function getNode()
     {
         return $this->node;
     }

src/Phpml/NeuralNetwork/Training/Backpropagation.php

@@ -24,16 +24,12 @@ class Backpropagation
      */
     private $prevSigmas = null;
 
-    /**
-     * @param int $theta
-     */
     public function __construct(int $theta)
     {
         $this->theta = $theta;
     }
 
     /**
-     * @param array $layers
      * @param mixed $targetClass
      */
     public function backpropagate(array $layers, $targetClass)
@@ -59,15 +55,7 @@ class Backpropagation
         $this->prevSigmas = null;
     }
 
-    /**
+    private function getSigma(Neuron $neuron, int $targetClass, int $key, bool $lastLayer) : float
-     * @param Neuron $neuron
-     * @param int    $targetClass
-     * @param int    $key
-     * @param bool   $lastLayer
-     *
-     * @return float
-     */
-    private function getSigma(Neuron $neuron, int $targetClass, int $key, bool $lastLayer): float
     {
         $neuronOutput = $neuron->getOutput();
         $sigma = $neuronOutput * (1 - $neuronOutput);
@@ -87,12 +75,7 @@ class Backpropagation
         return $sigma;
     }
 
-    /**
+    private function getPrevSigma(Neuron $neuron) : float
-     * @param Neuron $neuron
-     *
-     * @return float
-     */
-    private function getPrevSigma(Neuron $neuron): float
     {
         $sigma = 0.0;
 

src/Phpml/NeuralNetwork/Training/Backpropagation/Sigma.php

@@ -18,38 +18,23 @@ class Sigma
      */
     private $sigma;
 
-    /**
+    public function __construct(Neuron $neuron, float $sigma)
-     * @param Neuron $neuron
-     * @param float  $sigma
-     */
-    public function __construct(Neuron $neuron, $sigma)
     {
         $this->neuron = $neuron;
         $this->sigma = $sigma;
     }
 
-    /**
+    public function getNeuron(): Neuron
-     * @return Neuron
-     */
-    public function getNeuron()
     {
         return $this->neuron;
     }
 
-    /**
+    public function getSigma() : float
-     * @return float
-     */
-    public function getSigma()
     {
         return $this->sigma;
     }
 
-    /**
+    public function getSigmaForNeuron(Neuron $neuron) : float
-     * @param Neuron $neuron
-     *
-     * @return float
-     */
-    public function getSigmaForNeuron(Neuron $neuron): float
     {
         $sigma = 0.0;
 

src/Phpml/Pipeline.php

@@ -29,17 +29,11 @@ class Pipeline implements Estimator
         $this->estimator = $estimator;
     }
 
-    /**
-     * @param Transformer $transformer
-     */
     public function addTransformer(Transformer $transformer)
     {
         $this->transformers[] = $transformer;
     }
 
-    /**
-     * @param Estimator $estimator
-     */
     public function setEstimator(Estimator $estimator)
     {
         $this->estimator = $estimator;
@@ -48,15 +42,12 @@ class Pipeline implements Estimator
     /**
      * @return array|Transformer[]
      */
-    public function getTransformers()
+    public function getTransformers() : array
     {
         return $this->transformers;
     }
 
-    /**
+    public function getEstimator(): Estimator
-     * @return Estimator
-     */
-    public function getEstimator()
     {
         return $this->estimator;
     }

src/Phpml/Preprocessing/Imputer.php

@@ -81,7 +81,7 @@ class Imputer implements Preprocessor
      *
      * @return array
      */
-    private function getAxis(int $column, array $currentSample): array
+    private function getAxis(int $column, array $currentSample) : array
     {
         if (self::AXIS_ROW === $this->axis) {
             return array_diff($currentSample, [$this->missingValue]);

src/Phpml/Preprocessing/Imputer/Strategy/MeanStrategy.php

@@ -4,17 +4,15 @@ declare(strict_types=1);
 
 namespace Phpml\Preprocessing\Imputer\Strategy;
 
-use Phpml\Preprocessing\Imputer\Strategy;
 use Phpml\Math\Statistic\Mean;
+use Phpml\Preprocessing\Imputer\Strategy;
 
 class MeanStrategy implements Strategy
 {
     /**
      * @param array $currentAxis
-     *
-     * @return float
      */
-    public function replaceValue(array $currentAxis)
+    public function replaceValue(array $currentAxis) : float
     {
         return Mean::arithmetic($currentAxis);
     }

src/Phpml/Preprocessing/Imputer/Strategy/MedianStrategy.php

@@ -4,17 +4,15 @@ declare(strict_types=1);
 
 namespace Phpml\Preprocessing\Imputer\Strategy;
 
-use Phpml\Preprocessing\Imputer\Strategy;
 use Phpml\Math\Statistic\Mean;
+use Phpml\Preprocessing\Imputer\Strategy;
 
 class MedianStrategy implements Strategy
 {
     /**
      * @param array $currentAxis
-     *
-     * @return float
      */
-    public function replaceValue(array $currentAxis)
+    public function replaceValue(array $currentAxis) : float
     {
         return Mean::median($currentAxis);
     }

src/Phpml/Preprocessing/Imputer/Strategy/MostFrequentStrategy.php

@@ -4,8 +4,8 @@ declare(strict_types=1);
 
 namespace Phpml\Preprocessing\Imputer\Strategy;
 
-use Phpml\Preprocessing\Imputer\Strategy;
 use Phpml\Math\Statistic\Mean;
+use Phpml\Preprocessing\Imputer\Strategy;
 
 class MostFrequentStrategy implements Strategy
 {

src/Phpml/Preprocessing/Normalizer.php

@@ -5,8 +5,8 @@ declare(strict_types=1);
 namespace Phpml\Preprocessing;
 
 use Phpml\Exception\NormalizerException;
-use Phpml\Math\Statistic\StandardDeviation;
 use Phpml\Math\Statistic\Mean;
+use Phpml\Math\Statistic\StandardDeviation;
 
 class Normalizer implements Preprocessor
 {
@@ -35,8 +35,6 @@ class Normalizer implements Preprocessor
     private $mean;
 
     /**
-     * @param int $norm
-     *
      * @throws NormalizerException
      */
     public function __construct(int $norm = self::NORM_L2)

src/Phpml/Regression/LeastSquares.php

@@ -30,10 +30,6 @@ class LeastSquares implements Regression
      */
     private $coefficients;
 
-    /**
-     * @param array $samples
-     * @param array $targets
-     */
     public function train(array $samples, array $targets)
     {
         $this->samples = array_merge($this->samples, $samples);
@@ -43,8 +39,6 @@ class LeastSquares implements Regression
     }
 
     /**
-     * @param array $sample
-     *
      * @return mixed
      */
     public function predictSample(array $sample)
@@ -57,18 +51,12 @@ class LeastSquares implements Regression
         return $result;
     }
 
-    /**
+    public function getCoefficients() : array
-     * @return array
-     */
-    public function getCoefficients()
     {
         return $this->coefficients;
     }
 
-    /**
+    public function getIntercept() : float
-     * @return float
-     */
-    public function getIntercept()
     {
         return $this->intercept;
     }
@@ -90,10 +78,8 @@ class LeastSquares implements Regression
 
     /**
      * Add one dimension for intercept calculation.
-     *
-     * @return Matrix
      */
-    private function getSamplesMatrix()
+    private function getSamplesMatrix() : Matrix
     {
         $samples = [];
         foreach ($this->samples as $sample) {
@@ -104,10 +90,7 @@ class LeastSquares implements Regression
         return new Matrix($samples);
     }
 
-    /**
+    private function getTargetsMatrix() : Matrix
-     * @return Matrix
-     */
-    private function getTargetsMatrix()
     {
         if (is_array($this->targets[0])) {
             return new Matrix($this->targets);

src/Phpml/Regression/SVR.php

@@ -10,17 +10,6 @@ use Phpml\SupportVectorMachine\Type;
 
 class SVR extends SupportVectorMachine implements Regression
 {
-    /**
-     * @param int        $kernel
-     * @param int        $degree
-     * @param float      $epsilon
-     * @param float      $cost
-     * @param float|null $gamma
-     * @param float      $coef0
-     * @param float      $tolerance
-     * @param int        $cacheSize
-     * @param bool       $shrinking
-     */
     public function __construct(
         int $kernel = Kernel::RBF,
         int $degree = 3,

src/Phpml/SupportVectorMachine/DataTransformer.php

@@ -6,13 +6,6 @@ namespace Phpml\SupportVectorMachine;
 
 class DataTransformer
 {
-    /**
-     * @param array $samples
-     * @param array $labels
-     * @param bool  $targets
-     *
-     * @return string
-     */
     public static function trainingSet(array $samples, array $labels, bool $targets = false): string
     {
         $set = '';
@@ -27,11 +20,6 @@ class DataTransformer
         return $set;
     }
 
-    /**
-     * @param array $samples
-     *
-     * @return string
-     */
     public static function testSet(array $samples): string
     {
         if (!is_array($samples[0])) {
@@ -46,13 +34,7 @@ class DataTransformer
         return $set;
     }
 
-    /**
+    public static function predictions(string $rawPredictions, array $labels) : array
-     * @param string $rawPredictions
-     * @param array  $labels
-     *
-     * @return array
-     */
-    public static function predictions(string $rawPredictions, array $labels): array
     {
         $numericLabels = self::numericLabels($labels);
         $results = [];
@@ -65,12 +47,7 @@ class DataTransformer
         return $results;
     }
 
-    /**
+    public static function numericLabels(array $labels) : array
-     * @param array $labels
-     *
-     * @return array
-     */
-    public static function numericLabels(array $labels): array
     {
         $numericLabels = [];
         foreach ($labels as $label) {
@@ -84,11 +61,6 @@ class DataTransformer
         return $numericLabels;
     }
 
-    /**
-     * @param array $sample
-     *
-     * @return string
-     */
     private static function sampleRow(array $sample): string
     {
         $row = [];

src/Phpml/SupportVectorMachine/SupportVectorMachine.php

@@ -91,20 +91,6 @@ class SupportVectorMachine
      */
     private $targets = [];
 
-    /**
-     * @param int        $type
-     * @param int        $kernel
-     * @param float      $cost
-     * @param float      $nu
-     * @param int        $degree
-     * @param float|null $gamma
-     * @param float      $coef0
-     * @param float      $epsilon
-     * @param float      $tolerance
-     * @param int        $cacheSize
-     * @param bool       $shrinking
-     * @param bool       $probabilityEstimates
-     */
     public function __construct(
         int $type,
         int $kernel,
@@ -138,11 +124,6 @@ class SupportVectorMachine
         $this->varPath = $rootPath.'var'.DIRECTORY_SEPARATOR;
     }
 
-    /**
-     * @param string $binPath
-     *
-     * @throws InvalidArgumentException
-     */
     public function setBinPath(string $binPath)
     {
         $this->ensureDirectorySeparator($binPath);
@@ -151,11 +132,6 @@ class SupportVectorMachine
         $this->binPath = $binPath;
     }
 
-    /**
-     * @param string $varPath
-     *
-     * @throws InvalidArgumentException
-     */
     public function setVarPath(string $varPath)
     {
         if (!is_writable($varPath)) {
@@ -166,10 +142,6 @@ class SupportVectorMachine
         $this->varPath = $varPath;
     }
 
-    /**
-     * @param array $samples
-     * @param array $targets
-     */
     public function train(array $samples, array $targets)
     {
         $this->samples = array_merge($this->samples, $samples);
@@ -189,17 +161,12 @@ class SupportVectorMachine
         unlink($modelFileName);
     }
 
-    /**
+    public function getModel(): string
-     * @return string
-     */
-    public function getModel()
     {
         return $this->model;
     }
 
     /**
-     * @param array $samples
-     *
      * @return array
      */
     public function predict(array $samples)
@@ -232,10 +199,7 @@ class SupportVectorMachine
         return $predictions;
     }
 
-    /**
+    private function getOSExtension(): string
-     * @return string
-     */
-    private function getOSExtension()
     {
         $os = strtoupper(substr(PHP_OS, 0, 3));
         if ($os === 'WIN') {
@@ -247,12 +211,6 @@ class SupportVectorMachine
         return '';
     }
 
-    /**
-     * @param string $trainingSetFileName
-     * @param string $modelFileName
-     *
-     * @return string
-     */
     private function buildTrainCommand(string $trainingSetFileName, string $modelFileName): string
     {
         return sprintf(
@@ -276,9 +234,6 @@ class SupportVectorMachine
         );
     }
 
-    /**
-     * @param string $path
-     */
     private function ensureDirectorySeparator(string &$path)
     {
         if (substr($path, -1) !== DIRECTORY_SEPARATOR) {
@@ -286,11 +241,6 @@ class SupportVectorMachine
         }
     }
 
-    /**
-     * @param string $path
-     *
-     * @throws InvalidArgumentException
-     */
     private function verifyBinPath(string $path)
     {
         if (!is_dir($path)) {

src/Phpml/Tokenization/Tokenizer.php

@@ -6,10 +6,5 @@ namespace Phpml\Tokenization;
 
 interface Tokenizer
 {
-    /**
+    public function tokenize(string $text) : array;
-     * @param string $text
-     *
-     * @return array
-     */
-    public function tokenize(string $text): array;
 }

src/Phpml/Tokenization/WhitespaceTokenizer.php

@@ -6,12 +6,7 @@ namespace Phpml\Tokenization;
 
 class WhitespaceTokenizer implements Tokenizer
 {
-    /**
+    public function tokenize(string $text) : array
-     * @param string $text
-     *
-     * @return array
-     */
-    public function tokenize(string $text): array
     {
         return preg_split('/[\pZ\pC]+/u', $text, -1, PREG_SPLIT_NO_EMPTY);
     }

src/Phpml/Tokenization/WordTokenizer.php

@@ -6,12 +6,7 @@ namespace Phpml\Tokenization;
 
 class WordTokenizer implements Tokenizer
 {
-    /**
+    public function tokenize(string $text) : array
-     * @param string $text
-     *
-     * @return array
-     */
-    public function tokenize(string $text): array
     {
         $tokens = [];
         preg_match_all('/\w\w+/u', $text, $tokens);

tests/Phpml/Classification/Ensemble/BaggingTest.php

@@ -4,8 +4,8 @@ declare(strict_types=1);
 
 namespace tests\Phpml\Classification\Ensemble;
 
-use Phpml\Classification\Ensemble\Bagging;
 use Phpml\Classification\DecisionTree;
+use Phpml\Classification\Ensemble\Bagging;
 use Phpml\Classification\NaiveBayes;
 use Phpml\ModelManager;
 use PHPUnit\Framework\TestCase;

tests/Phpml/Classification/Ensemble/RandomForestTest.php

@@ -4,8 +4,8 @@ declare(strict_types=1);
 
 namespace tests\Phpml\Classification\Ensemble;
 
-use Phpml\Classification\Ensemble\RandomForest;
 use Phpml\Classification\DecisionTree;
+use Phpml\Classification\Ensemble\RandomForest;
 use Phpml\Classification\NaiveBayes;
 
 class RandomForestTest extends BaggingTest

tests/Phpml/Classification/MLPClassifierTest.php

@@ -5,8 +5,8 @@ declare(strict_types=1);
 namespace tests\Phpml\Classification;
 
 use Phpml\Classification\MLPClassifier;
-use Phpml\NeuralNetwork\Node\Neuron;
 use Phpml\ModelManager;
+use Phpml\NeuralNetwork\Node\Neuron;
 use PHPUnit\Framework\TestCase;
 
 class MLPClassifierTest extends TestCase
@@ -194,7 +194,7 @@ class MLPClassifierTest extends TestCase
      *
      * @return array
      */
-    private function getSynapsesNodes(array $synapses): array
+    private function getSynapsesNodes(array $synapses) : array
     {
         $nodes = [];
         foreach ($synapses as $synapse) {

tests/Phpml/Classification/SVCTest.php

@@ -5,8 +5,8 @@ declare(strict_types=1);
 namespace tests\Phpml\Classification;
 
 use Phpml\Classification\SVC;
-use Phpml\SupportVectorMachine\Kernel;
 use Phpml\ModelManager;
+use Phpml\SupportVectorMachine\Kernel;
 use PHPUnit\Framework\TestCase;
 
 class SVCTest extends TestCase