diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5c8f2ae..781d5fd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,8 +3,10 @@ CHANGELOG
 
 This changelog references the relevant changes done in PHP-ML library.
 
-* 0.2.1 (in plan/progress)
+* 0.2.2 (in plan/progress)
     * feature [Regression] - SSE, SSTo, SSR  - sum of the squared
+
+* 0.2.1 (2016-11-20)
     * feature [Association] - Apriori algorithm implementation
     * bug [Metric] - division by zero
 
diff --git a/src/Phpml/Association/Apriori.php b/src/Phpml/Association/Apriori.php
index bec1510..4855691 100644
--- a/src/Phpml/Association/Apriori.php
+++ b/src/Phpml/Association/Apriori.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Association;
 
diff --git a/src/Phpml/Association/Associator.php b/src/Phpml/Association/Associator.php
index 53e894a..c339b5e 100644
--- a/src/Phpml/Association/Associator.php
+++ b/src/Phpml/Association/Associator.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Association;
 
diff --git a/src/Phpml/Classification/Classifier.php b/src/Phpml/Classification/Classifier.php
index 1477904..01c0984 100644
--- a/src/Phpml/Classification/Classifier.php
+++ b/src/Phpml/Classification/Classifier.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Classification;
 
diff --git a/src/Phpml/Classification/KNearestNeighbors.php b/src/Phpml/Classification/KNearestNeighbors.php
index 594438b..b52c95b 100644
--- a/src/Phpml/Classification/KNearestNeighbors.php
+++ b/src/Phpml/Classification/KNearestNeighbors.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Classification;
 
diff --git a/src/Phpml/Classification/NaiveBayes.php b/src/Phpml/Classification/NaiveBayes.php
index 3e7d819..41441be 100644
--- a/src/Phpml/Classification/NaiveBayes.php
+++ b/src/Phpml/Classification/NaiveBayes.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Classification;
 
diff --git a/src/Phpml/Classification/SVC.php b/src/Phpml/Classification/SVC.php
index 2350d5d..38ae9c4 100644
--- a/src/Phpml/Classification/SVC.php
+++ b/src/Phpml/Classification/SVC.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Classification;
 
diff --git a/src/Phpml/Clustering/Clusterer.php b/src/Phpml/Clustering/Clusterer.php
index 8324b41..0c58b2e 100644
--- a/src/Phpml/Clustering/Clusterer.php
+++ b/src/Phpml/Clustering/Clusterer.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Clustering;
 
diff --git a/src/Phpml/Clustering/DBSCAN.php b/src/Phpml/Clustering/DBSCAN.php
index e20c645..ebb1f5d 100644
--- a/src/Phpml/Clustering/DBSCAN.php
+++ b/src/Phpml/Clustering/DBSCAN.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Clustering;
 
diff --git a/src/Phpml/Clustering/KMeans.php b/src/Phpml/Clustering/KMeans.php
index c5372b0..a9e9083 100644
--- a/src/Phpml/Clustering/KMeans.php
+++ b/src/Phpml/Clustering/KMeans.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Clustering;
 
diff --git a/src/Phpml/Clustering/KMeans/Cluster.php b/src/Phpml/Clustering/KMeans/Cluster.php
index 5cd974d..c160b6c 100644
--- a/src/Phpml/Clustering/KMeans/Cluster.php
+++ b/src/Phpml/Clustering/KMeans/Cluster.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Clustering\KMeans;
 
diff --git a/src/Phpml/Clustering/KMeans/Point.php b/src/Phpml/Clustering/KMeans/Point.php
index 5dcf5ec..a8d72e5 100644
--- a/src/Phpml/Clustering/KMeans/Point.php
+++ b/src/Phpml/Clustering/KMeans/Point.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Clustering\KMeans;
 
@@ -46,7 +46,7 @@ class Point implements ArrayAccess
         $distance = 0;
         for ($n = 0; $n < $this->dimension; ++$n) {
             $difference = $this->coordinates[$n] - $point->coordinates[$n];
-            $distance  += $difference * $difference;
+            $distance += $difference * $difference;
         }
 
         return $precise ? sqrt((float) $distance) : $distance;
diff --git a/src/Phpml/Clustering/KMeans/Space.php b/src/Phpml/Clustering/KMeans/Space.php
index 89a0d09..40b1f1d 100644
--- a/src/Phpml/Clustering/KMeans/Space.php
+++ b/src/Phpml/Clustering/KMeans/Space.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Clustering\KMeans;
 
diff --git a/src/Phpml/CrossValidation/RandomSplit.php b/src/Phpml/CrossValidation/RandomSplit.php
index c1e709e..69c44c1 100644
--- a/src/Phpml/CrossValidation/RandomSplit.php
+++ b/src/Phpml/CrossValidation/RandomSplit.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\CrossValidation;
 
diff --git a/src/Phpml/CrossValidation/Split.php b/src/Phpml/CrossValidation/Split.php
index 3478f54..add181c 100644
--- a/src/Phpml/CrossValidation/Split.php
+++ b/src/Phpml/CrossValidation/Split.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\CrossValidation;
 
diff --git a/src/Phpml/CrossValidation/StratifiedRandomSplit.php b/src/Phpml/CrossValidation/StratifiedRandomSplit.php
index 10af303..e6c80a2 100644
--- a/src/Phpml/CrossValidation/StratifiedRandomSplit.php
+++ b/src/Phpml/CrossValidation/StratifiedRandomSplit.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\CrossValidation;
 
diff --git a/src/Phpml/Dataset/ArrayDataset.php b/src/Phpml/Dataset/ArrayDataset.php
index fd471e1..6f765fe 100644
--- a/src/Phpml/Dataset/ArrayDataset.php
+++ b/src/Phpml/Dataset/ArrayDataset.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Dataset;
 
diff --git a/src/Phpml/Dataset/CsvDataset.php b/src/Phpml/Dataset/CsvDataset.php
index b552d47..377f84c 100644
--- a/src/Phpml/Dataset/CsvDataset.php
+++ b/src/Phpml/Dataset/CsvDataset.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Dataset;
 
diff --git a/src/Phpml/Dataset/Dataset.php b/src/Phpml/Dataset/Dataset.php
index 791dcb4..f851d85 100644
--- a/src/Phpml/Dataset/Dataset.php
+++ b/src/Phpml/Dataset/Dataset.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Dataset;
 
diff --git a/src/Phpml/Dataset/Demo/GlassDataset.php b/src/Phpml/Dataset/Demo/GlassDataset.php
index aa591f3..6f8eda8 100644
--- a/src/Phpml/Dataset/Demo/GlassDataset.php
+++ b/src/Phpml/Dataset/Demo/GlassDataset.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Dataset\Demo;
 
diff --git a/src/Phpml/Dataset/Demo/IrisDataset.php b/src/Phpml/Dataset/Demo/IrisDataset.php
index 509d9f4..6a3a422 100644
--- a/src/Phpml/Dataset/Demo/IrisDataset.php
+++ b/src/Phpml/Dataset/Demo/IrisDataset.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Dataset\Demo;
 
diff --git a/src/Phpml/Dataset/Demo/WineDataset.php b/src/Phpml/Dataset/Demo/WineDataset.php
index 90ddfe4..f522e01 100644
--- a/src/Phpml/Dataset/Demo/WineDataset.php
+++ b/src/Phpml/Dataset/Demo/WineDataset.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Dataset\Demo;
 
diff --git a/src/Phpml/Dataset/FilesDataset.php b/src/Phpml/Dataset/FilesDataset.php
index 6897ba1..f7c789f 100644
--- a/src/Phpml/Dataset/FilesDataset.php
+++ b/src/Phpml/Dataset/FilesDataset.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Dataset;
 
diff --git a/src/Phpml/Estimator.php b/src/Phpml/Estimator.php
index 0631679..8b98bb6 100644
--- a/src/Phpml/Estimator.php
+++ b/src/Phpml/Estimator.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml;
 
diff --git a/src/Phpml/Exception/DatasetException.php b/src/Phpml/Exception/DatasetException.php
index 813166b..4d33310 100644
--- a/src/Phpml/Exception/DatasetException.php
+++ b/src/Phpml/Exception/DatasetException.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Exception;
 
diff --git a/src/Phpml/Exception/InvalidArgumentException.php b/src/Phpml/Exception/InvalidArgumentException.php
index 86cfd86..b02da53 100644
--- a/src/Phpml/Exception/InvalidArgumentException.php
+++ b/src/Phpml/Exception/InvalidArgumentException.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Exception;
 
diff --git a/src/Phpml/Exception/MatrixException.php b/src/Phpml/Exception/MatrixException.php
index 440a0ac..9aaa43a 100644
--- a/src/Phpml/Exception/MatrixException.php
+++ b/src/Phpml/Exception/MatrixException.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Exception;
 
diff --git a/src/Phpml/Exception/NormalizerException.php b/src/Phpml/Exception/NormalizerException.php
index 9f88f0c..e9762d3 100644
--- a/src/Phpml/Exception/NormalizerException.php
+++ b/src/Phpml/Exception/NormalizerException.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Exception;
 
diff --git a/src/Phpml/FeatureExtraction/StopWords.php b/src/Phpml/FeatureExtraction/StopWords.php
index cb4ccc8..ad01bbb 100644
--- a/src/Phpml/FeatureExtraction/StopWords.php
+++ b/src/Phpml/FeatureExtraction/StopWords.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\FeatureExtraction;
 
diff --git a/src/Phpml/FeatureExtraction/StopWords/English.php b/src/Phpml/FeatureExtraction/StopWords/English.php
index 841ef37..fab079b 100644
--- a/src/Phpml/FeatureExtraction/StopWords/English.php
+++ b/src/Phpml/FeatureExtraction/StopWords/English.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\FeatureExtraction\StopWords;
 
diff --git a/src/Phpml/FeatureExtraction/StopWords/Polish.php b/src/Phpml/FeatureExtraction/StopWords/Polish.php
index f591384..e452ebf 100644
--- a/src/Phpml/FeatureExtraction/StopWords/Polish.php
+++ b/src/Phpml/FeatureExtraction/StopWords/Polish.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\FeatureExtraction\StopWords;
 
diff --git a/src/Phpml/FeatureExtraction/TfIdfTransformer.php b/src/Phpml/FeatureExtraction/TfIdfTransformer.php
index 55629bd..2360560 100644
--- a/src/Phpml/FeatureExtraction/TfIdfTransformer.php
+++ b/src/Phpml/FeatureExtraction/TfIdfTransformer.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\FeatureExtraction;
 
diff --git a/src/Phpml/FeatureExtraction/TokenCountVectorizer.php b/src/Phpml/FeatureExtraction/TokenCountVectorizer.php
index 56d63e2..4371a7d 100644
--- a/src/Phpml/FeatureExtraction/TokenCountVectorizer.php
+++ b/src/Phpml/FeatureExtraction/TokenCountVectorizer.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\FeatureExtraction;
 
@@ -173,7 +173,7 @@ class TokenCountVectorizer implements Transformer
 
     /**
      * @param array $samples
-     * 
+     *
      * @return array
      */
     private function checkDocumentFrequency(array &$samples)
diff --git a/src/Phpml/Helper/Predictable.php b/src/Phpml/Helper/Predictable.php
index 4bf2a2e..097edaa 100644
--- a/src/Phpml/Helper/Predictable.php
+++ b/src/Phpml/Helper/Predictable.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Helper;
 
diff --git a/src/Phpml/Helper/Trainable.php b/src/Phpml/Helper/Trainable.php
index fda27d5..e58a1da 100644
--- a/src/Phpml/Helper/Trainable.php
+++ b/src/Phpml/Helper/Trainable.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Helper;
 
diff --git a/src/Phpml/Math/Distance.php b/src/Phpml/Math/Distance.php
index ed929b3..3df5c2c 100644
--- a/src/Phpml/Math/Distance.php
+++ b/src/Phpml/Math/Distance.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math;
 
diff --git a/src/Phpml/Math/Distance/Chebyshev.php b/src/Phpml/Math/Distance/Chebyshev.php
index 386d98a..ed2911c 100644
--- a/src/Phpml/Math/Distance/Chebyshev.php
+++ b/src/Phpml/Math/Distance/Chebyshev.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math\Distance;
 
diff --git a/src/Phpml/Math/Distance/Euclidean.php b/src/Phpml/Math/Distance/Euclidean.php
index 21a6aa9..ceaf510 100644
--- a/src/Phpml/Math/Distance/Euclidean.php
+++ b/src/Phpml/Math/Distance/Euclidean.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math\Distance;
 
diff --git a/src/Phpml/Math/Distance/Manhattan.php b/src/Phpml/Math/Distance/Manhattan.php
index 8253eb7..b6f6eb8 100644
--- a/src/Phpml/Math/Distance/Manhattan.php
+++ b/src/Phpml/Math/Distance/Manhattan.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math\Distance;
 
diff --git a/src/Phpml/Math/Distance/Minkowski.php b/src/Phpml/Math/Distance/Minkowski.php
index 5c08c03..cb13a7c 100644
--- a/src/Phpml/Math/Distance/Minkowski.php
+++ b/src/Phpml/Math/Distance/Minkowski.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math\Distance;
 
diff --git a/src/Phpml/Math/Kernel.php b/src/Phpml/Math/Kernel.php
index 953a5fa..6d1461f 100644
--- a/src/Phpml/Math/Kernel.php
+++ b/src/Phpml/Math/Kernel.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math;
 
diff --git a/src/Phpml/Math/Kernel/RBF.php b/src/Phpml/Math/Kernel/RBF.php
index 5e77681..8ca7d84 100644
--- a/src/Phpml/Math/Kernel/RBF.php
+++ b/src/Phpml/Math/Kernel/RBF.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math\Kernel;
 
diff --git a/src/Phpml/Math/Matrix.php b/src/Phpml/Math/Matrix.php
index 808472c..4e70305 100644
--- a/src/Phpml/Math/Matrix.php
+++ b/src/Phpml/Math/Matrix.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math;
 
@@ -113,7 +113,7 @@ class Matrix
 
     /**
      * @return float|int
-     * 
+     *
      * @throws MatrixException
      */
     public function getDeterminant()
diff --git a/src/Phpml/Math/Product.php b/src/Phpml/Math/Product.php
index 678dd71..35ef79c 100644
--- a/src/Phpml/Math/Product.php
+++ b/src/Phpml/Math/Product.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math;
 
diff --git a/src/Phpml/Math/Set.php b/src/Phpml/Math/Set.php
index b813a79..20fc780 100644
--- a/src/Phpml/Math/Set.php
+++ b/src/Phpml/Math/Set.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math;
 
diff --git a/src/Phpml/Math/Statistic/Correlation.php b/src/Phpml/Math/Statistic/Correlation.php
index e9c0e30..cc1767c 100644
--- a/src/Phpml/Math/Statistic/Correlation.php
+++ b/src/Phpml/Math/Statistic/Correlation.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math\Statistic;
 
@@ -30,7 +30,7 @@ class Correlation
         $a2 = 0;
         $b2 = 0;
 
-        for ($i = 0;$i < $count;++$i) {
+        for ($i = 0; $i < $count; ++$i) {
             $a = $x[$i] - $meanX;
             $b = $y[$i] - $meanY;
             $axb = $axb + ($a * $b);
diff --git a/src/Phpml/Math/Statistic/Mean.php b/src/Phpml/Math/Statistic/Mean.php
index 3804848..07c43fe 100644
--- a/src/Phpml/Math/Statistic/Mean.php
+++ b/src/Phpml/Math/Statistic/Mean.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math\Statistic;
 
diff --git a/src/Phpml/Math/Statistic/StandardDeviation.php b/src/Phpml/Math/Statistic/StandardDeviation.php
index 6e161fb..7655283 100644
--- a/src/Phpml/Math/Statistic/StandardDeviation.php
+++ b/src/Phpml/Math/Statistic/StandardDeviation.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Math\Statistic;
 
@@ -33,7 +33,7 @@ class StandardDeviation
         foreach ($a as $val) {
             $d = $val - $mean;
             $carry += $d * $d;
-        };
+        }
 
         if ($sample) {
             --$n;
diff --git a/src/Phpml/Metric/Accuracy.php b/src/Phpml/Metric/Accuracy.php
index 0565ead..0e9dc03 100644
--- a/src/Phpml/Metric/Accuracy.php
+++ b/src/Phpml/Metric/Accuracy.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Metric;
 
diff --git a/src/Phpml/Metric/ClassificationReport.php b/src/Phpml/Metric/ClassificationReport.php
index f56fb2a..3499590 100644
--- a/src/Phpml/Metric/ClassificationReport.php
+++ b/src/Phpml/Metric/ClassificationReport.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Metric;
 
@@ -113,7 +113,7 @@ class ClassificationReport
     {
         foreach (['precision', 'recall', 'f1score'] as $metric) {
             $values = array_filter($this->$metric);
-            if(0==count($values)) {
+            if (0 == count($values)) {
                 $this->average[$metric] = 0.0;
                 continue;
             }
diff --git a/src/Phpml/Metric/ConfusionMatrix.php b/src/Phpml/Metric/ConfusionMatrix.php
index 6aeaa87..664e355 100644
--- a/src/Phpml/Metric/ConfusionMatrix.php
+++ b/src/Phpml/Metric/ConfusionMatrix.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Metric;
 
diff --git a/src/Phpml/NeuralNetwork/ActivationFunction.php b/src/Phpml/NeuralNetwork/ActivationFunction.php
index 9b7d984..f209f34 100644
--- a/src/Phpml/NeuralNetwork/ActivationFunction.php
+++ b/src/Phpml/NeuralNetwork/ActivationFunction.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork;
 
diff --git a/src/Phpml/NeuralNetwork/ActivationFunction/BinaryStep.php b/src/Phpml/NeuralNetwork/ActivationFunction/BinaryStep.php
index 7cad1ca..350404b 100644
--- a/src/Phpml/NeuralNetwork/ActivationFunction/BinaryStep.php
+++ b/src/Phpml/NeuralNetwork/ActivationFunction/BinaryStep.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork\ActivationFunction;
 
diff --git a/src/Phpml/NeuralNetwork/ActivationFunction/Gaussian.php b/src/Phpml/NeuralNetwork/ActivationFunction/Gaussian.php
index cdbe4ae..0e3e848 100644
--- a/src/Phpml/NeuralNetwork/ActivationFunction/Gaussian.php
+++ b/src/Phpml/NeuralNetwork/ActivationFunction/Gaussian.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork\ActivationFunction;
 
diff --git a/src/Phpml/NeuralNetwork/ActivationFunction/HyperbolicTangent.php b/src/Phpml/NeuralNetwork/ActivationFunction/HyperbolicTangent.php
index 69921e9..93b1001 100644
--- a/src/Phpml/NeuralNetwork/ActivationFunction/HyperbolicTangent.php
+++ b/src/Phpml/NeuralNetwork/ActivationFunction/HyperbolicTangent.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork\ActivationFunction;
 
diff --git a/src/Phpml/NeuralNetwork/ActivationFunction/Sigmoid.php b/src/Phpml/NeuralNetwork/ActivationFunction/Sigmoid.php
index ee7b7be..23ac7ce 100644
--- a/src/Phpml/NeuralNetwork/ActivationFunction/Sigmoid.php
+++ b/src/Phpml/NeuralNetwork/ActivationFunction/Sigmoid.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork\ActivationFunction;
 
diff --git a/src/Phpml/NeuralNetwork/Layer.php b/src/Phpml/NeuralNetwork/Layer.php
index b94da21..632bc00 100644
--- a/src/Phpml/NeuralNetwork/Layer.php
+++ b/src/Phpml/NeuralNetwork/Layer.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork;
 
diff --git a/src/Phpml/NeuralNetwork/Network.php b/src/Phpml/NeuralNetwork/Network.php
index a03b8b6..c6c25af 100644
--- a/src/Phpml/NeuralNetwork/Network.php
+++ b/src/Phpml/NeuralNetwork/Network.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork;
 
diff --git a/src/Phpml/NeuralNetwork/Network/LayeredNetwork.php b/src/Phpml/NeuralNetwork/Network/LayeredNetwork.php
index 4413403..af2d723 100644
--- a/src/Phpml/NeuralNetwork/Network/LayeredNetwork.php
+++ b/src/Phpml/NeuralNetwork/Network/LayeredNetwork.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork\Network;
 
diff --git a/src/Phpml/NeuralNetwork/Network/MultilayerPerceptron.php b/src/Phpml/NeuralNetwork/Network/MultilayerPerceptron.php
index e97e045..04664f9 100644
--- a/src/Phpml/NeuralNetwork/Network/MultilayerPerceptron.php
+++ b/src/Phpml/NeuralNetwork/Network/MultilayerPerceptron.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork\Network;
 
@@ -64,7 +64,7 @@ class MultilayerPerceptron extends LayeredNetwork
     private function addBiasNodes()
     {
         $biasLayers = count($this->layers) - 1;
-        for ($i = 0;$i < $biasLayers;++$i) {
+        for ($i = 0; $i < $biasLayers; ++$i) {
             $this->layers[$i]->addNode(new Bias());
         }
     }
diff --git a/src/Phpml/NeuralNetwork/Node.php b/src/Phpml/NeuralNetwork/Node.php
index 77e0c00..65d5cdc 100644
--- a/src/Phpml/NeuralNetwork/Node.php
+++ b/src/Phpml/NeuralNetwork/Node.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork;
 
diff --git a/src/Phpml/NeuralNetwork/Node/Bias.php b/src/Phpml/NeuralNetwork/Node/Bias.php
index f19dcb6..bf2e5ff 100644
--- a/src/Phpml/NeuralNetwork/Node/Bias.php
+++ b/src/Phpml/NeuralNetwork/Node/Bias.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork\Node;
 
diff --git a/src/Phpml/NeuralNetwork/Node/Input.php b/src/Phpml/NeuralNetwork/Node/Input.php
index d95344e..1531868 100644
--- a/src/Phpml/NeuralNetwork/Node/Input.php
+++ b/src/Phpml/NeuralNetwork/Node/Input.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork\Node;
 
diff --git a/src/Phpml/NeuralNetwork/Node/Neuron.php b/src/Phpml/NeuralNetwork/Node/Neuron.php
index 677831e..5194438 100644
--- a/src/Phpml/NeuralNetwork/Node/Neuron.php
+++ b/src/Phpml/NeuralNetwork/Node/Neuron.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork\Node;
 
diff --git a/src/Phpml/NeuralNetwork/Node/Neuron/Synapse.php b/src/Phpml/NeuralNetwork/Node/Neuron/Synapse.php
index 3813d71..0fb54b1 100644
--- a/src/Phpml/NeuralNetwork/Node/Neuron/Synapse.php
+++ b/src/Phpml/NeuralNetwork/Node/Neuron/Synapse.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork\Node\Neuron;
 
diff --git a/src/Phpml/NeuralNetwork/Training.php b/src/Phpml/NeuralNetwork/Training.php
index 932f189..d876af2 100644
--- a/src/Phpml/NeuralNetwork/Training.php
+++ b/src/Phpml/NeuralNetwork/Training.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork;
 
diff --git a/src/Phpml/NeuralNetwork/Training/Backpropagation.php b/src/Phpml/NeuralNetwork/Training/Backpropagation.php
index 3f80bf5..136e8bf 100644
--- a/src/Phpml/NeuralNetwork/Training/Backpropagation.php
+++ b/src/Phpml/NeuralNetwork/Training/Backpropagation.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork\Training;
 
@@ -126,7 +126,7 @@ class Backpropagation implements Training
 
     /**
      * @param Neuron $neuron
-     * 
+     *
      * @return float
      */
     private function getPrevSigma(Neuron $neuron): float
diff --git a/src/Phpml/NeuralNetwork/Training/Backpropagation/Sigma.php b/src/Phpml/NeuralNetwork/Training/Backpropagation/Sigma.php
index 8520354..62e2e7a 100644
--- a/src/Phpml/NeuralNetwork/Training/Backpropagation/Sigma.php
+++ b/src/Phpml/NeuralNetwork/Training/Backpropagation/Sigma.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\NeuralNetwork\Training\Backpropagation;
 
diff --git a/src/Phpml/Pipeline.php b/src/Phpml/Pipeline.php
index b55abca..a6b3d56 100644
--- a/src/Phpml/Pipeline.php
+++ b/src/Phpml/Pipeline.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml;
 
@@ -20,7 +20,7 @@ class Pipeline implements Estimator
      * @param array|Transformer[] $transformers
      * @param Estimator           $estimator
      */
-    public function __construct(array $transformers = [], Estimator $estimator)
+    public function __construct(array $transformers, Estimator $estimator)
     {
         foreach ($transformers as $transformer) {
             $this->addTransformer($transformer);
diff --git a/src/Phpml/Preprocessing/Imputer.php b/src/Phpml/Preprocessing/Imputer.php
index 012bb79..805d3f6 100644
--- a/src/Phpml/Preprocessing/Imputer.php
+++ b/src/Phpml/Preprocessing/Imputer.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Preprocessing;
 
@@ -37,7 +37,7 @@ class Imputer implements Preprocessor
      * @param int        $axis
      * @param array|null $samples
      */
-    public function __construct($missingValue = null, Strategy $strategy, int $axis = self::AXIS_COLUMN, array $samples = [])
+    public function __construct($missingValue, Strategy $strategy, int $axis = self::AXIS_COLUMN, array $samples = [])
     {
         $this->missingValue = $missingValue;
         $this->strategy = $strategy;
@@ -78,7 +78,7 @@ class Imputer implements Preprocessor
     /**
      * @param int   $column
      * @param array $currentSample
-     * 
+     *
      * @return array
      */
     private function getAxis(int $column, array $currentSample): array
diff --git a/src/Phpml/Preprocessing/Imputer/Strategy.php b/src/Phpml/Preprocessing/Imputer/Strategy.php
index 2cf1144..9125e06 100644
--- a/src/Phpml/Preprocessing/Imputer/Strategy.php
+++ b/src/Phpml/Preprocessing/Imputer/Strategy.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Preprocessing\Imputer;
 
diff --git a/src/Phpml/Preprocessing/Imputer/Strategy/MeanStrategy.php b/src/Phpml/Preprocessing/Imputer/Strategy/MeanStrategy.php
index 12a732b..88fbd3a 100644
--- a/src/Phpml/Preprocessing/Imputer/Strategy/MeanStrategy.php
+++ b/src/Phpml/Preprocessing/Imputer/Strategy/MeanStrategy.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Preprocessing\Imputer\Strategy;
 
@@ -11,7 +11,7 @@ class MeanStrategy implements Strategy
 {
     /**
      * @param array $currentAxis
-     * 
+     *
      * @return float
      */
     public function replaceValue(array $currentAxis)
diff --git a/src/Phpml/Preprocessing/Imputer/Strategy/MedianStrategy.php b/src/Phpml/Preprocessing/Imputer/Strategy/MedianStrategy.php
index 3746760..d4e19e0 100644
--- a/src/Phpml/Preprocessing/Imputer/Strategy/MedianStrategy.php
+++ b/src/Phpml/Preprocessing/Imputer/Strategy/MedianStrategy.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Preprocessing\Imputer\Strategy;
 
@@ -11,7 +11,7 @@ class MedianStrategy implements Strategy
 {
     /**
      * @param array $currentAxis
-     * 
+     *
      * @return float
      */
     public function replaceValue(array $currentAxis)
diff --git a/src/Phpml/Preprocessing/Imputer/Strategy/MostFrequentStrategy.php b/src/Phpml/Preprocessing/Imputer/Strategy/MostFrequentStrategy.php
index 690a97c..0bf8e8c 100644
--- a/src/Phpml/Preprocessing/Imputer/Strategy/MostFrequentStrategy.php
+++ b/src/Phpml/Preprocessing/Imputer/Strategy/MostFrequentStrategy.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Preprocessing\Imputer\Strategy;
 
@@ -11,7 +11,7 @@ class MostFrequentStrategy implements Strategy
 {
     /**
      * @param array $currentAxis
-     * 
+     *
      * @return float|mixed
      */
     public function replaceValue(array $currentAxis)
diff --git a/src/Phpml/Preprocessing/Normalizer.php b/src/Phpml/Preprocessing/Normalizer.php
index fa62dde..591ca72 100644
--- a/src/Phpml/Preprocessing/Normalizer.php
+++ b/src/Phpml/Preprocessing/Normalizer.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Preprocessing;
 
diff --git a/src/Phpml/Preprocessing/Preprocessor.php b/src/Phpml/Preprocessing/Preprocessor.php
index ae70941..3ec1566 100644
--- a/src/Phpml/Preprocessing/Preprocessor.php
+++ b/src/Phpml/Preprocessing/Preprocessor.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Preprocessing;
 
diff --git a/src/Phpml/Regression/LeastSquares.php b/src/Phpml/Regression/LeastSquares.php
index 83a6a65..19609fb 100644
--- a/src/Phpml/Regression/LeastSquares.php
+++ b/src/Phpml/Regression/LeastSquares.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Regression;
 
diff --git a/src/Phpml/Regression/MLPRegressor.php b/src/Phpml/Regression/MLPRegressor.php
index 9a84214..72e6a81 100644
--- a/src/Phpml/Regression/MLPRegressor.php
+++ b/src/Phpml/Regression/MLPRegressor.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Regression;
 
diff --git a/src/Phpml/Regression/Regression.php b/src/Phpml/Regression/Regression.php
index 27a1b83..542685c 100644
--- a/src/Phpml/Regression/Regression.php
+++ b/src/Phpml/Regression/Regression.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Regression;
 
diff --git a/src/Phpml/Regression/SVR.php b/src/Phpml/Regression/SVR.php
index 07b1459..78c57cb 100644
--- a/src/Phpml/Regression/SVR.php
+++ b/src/Phpml/Regression/SVR.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Regression;
 
diff --git a/src/Phpml/SupportVectorMachine/DataTransformer.php b/src/Phpml/SupportVectorMachine/DataTransformer.php
index 7dd45d8..238a7d2 100644
--- a/src/Phpml/SupportVectorMachine/DataTransformer.php
+++ b/src/Phpml/SupportVectorMachine/DataTransformer.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\SupportVectorMachine;
 
diff --git a/src/Phpml/SupportVectorMachine/Kernel.php b/src/Phpml/SupportVectorMachine/Kernel.php
index 4dddef6..9918a3f 100644
--- a/src/Phpml/SupportVectorMachine/Kernel.php
+++ b/src/Phpml/SupportVectorMachine/Kernel.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\SupportVectorMachine;
 
diff --git a/src/Phpml/SupportVectorMachine/SupportVectorMachine.php b/src/Phpml/SupportVectorMachine/SupportVectorMachine.php
index 65b8ef6..2bef22f 100644
--- a/src/Phpml/SupportVectorMachine/SupportVectorMachine.php
+++ b/src/Phpml/SupportVectorMachine/SupportVectorMachine.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\SupportVectorMachine;
 
diff --git a/src/Phpml/SupportVectorMachine/Type.php b/src/Phpml/SupportVectorMachine/Type.php
index 49b03a0..1b454a5 100644
--- a/src/Phpml/SupportVectorMachine/Type.php
+++ b/src/Phpml/SupportVectorMachine/Type.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\SupportVectorMachine;
 
diff --git a/src/Phpml/Tokenization/Tokenizer.php b/src/Phpml/Tokenization/Tokenizer.php
index 5539a85..9a145c5 100644
--- a/src/Phpml/Tokenization/Tokenizer.php
+++ b/src/Phpml/Tokenization/Tokenizer.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Tokenization;
 
@@ -8,7 +8,7 @@ interface Tokenizer
 {
     /**
      * @param string $text
-     * 
+     *
      * @return array
      */
     public function tokenize(string $text): array;
diff --git a/src/Phpml/Tokenization/WhitespaceTokenizer.php b/src/Phpml/Tokenization/WhitespaceTokenizer.php
index b4bf9e5..ff91829 100644
--- a/src/Phpml/Tokenization/WhitespaceTokenizer.php
+++ b/src/Phpml/Tokenization/WhitespaceTokenizer.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Tokenization;
 
diff --git a/src/Phpml/Tokenization/WordTokenizer.php b/src/Phpml/Tokenization/WordTokenizer.php
index c384c39..431ae00 100644
--- a/src/Phpml/Tokenization/WordTokenizer.php
+++ b/src/Phpml/Tokenization/WordTokenizer.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml\Tokenization;
 
diff --git a/src/Phpml/Transformer.php b/src/Phpml/Transformer.php
index f7ddd81..c36e5ca 100644
--- a/src/Phpml/Transformer.php
+++ b/src/Phpml/Transformer.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace Phpml;
 
diff --git a/tests/Phpml/Association/AprioriTest.php b/tests/Phpml/Association/AprioriTest.php
index 2fb2937..57ef5de 100644
--- a/tests/Phpml/Association/AprioriTest.php
+++ b/tests/Phpml/Association/AprioriTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Classification;
 
diff --git a/tests/Phpml/Classification/KNearestNeighborsTest.php b/tests/Phpml/Classification/KNearestNeighborsTest.php
index 1f6f99f..7c5a75a 100644
--- a/tests/Phpml/Classification/KNearestNeighborsTest.php
+++ b/tests/Phpml/Classification/KNearestNeighborsTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Classification;
 
diff --git a/tests/Phpml/Classification/NaiveBayesTest.php b/tests/Phpml/Classification/NaiveBayesTest.php
index 3482cf5..f2edb02 100644
--- a/tests/Phpml/Classification/NaiveBayesTest.php
+++ b/tests/Phpml/Classification/NaiveBayesTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Classification;
 
diff --git a/tests/Phpml/Classification/SVCTest.php b/tests/Phpml/Classification/SVCTest.php
index 1ddcdd0..8b17b53 100644
--- a/tests/Phpml/Classification/SVCTest.php
+++ b/tests/Phpml/Classification/SVCTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Classification;
 
diff --git a/tests/Phpml/Clustering/DBSCANTest.php b/tests/Phpml/Clustering/DBSCANTest.php
index be37fff..b631508 100644
--- a/tests/Phpml/Clustering/DBSCANTest.php
+++ b/tests/Phpml/Clustering/DBSCANTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Clustering;
 
diff --git a/tests/Phpml/Clustering/KMeansTest.php b/tests/Phpml/Clustering/KMeansTest.php
index 79b5ce7..aa4d9c3 100644
--- a/tests/Phpml/Clustering/KMeansTest.php
+++ b/tests/Phpml/Clustering/KMeansTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Clustering;
 
diff --git a/tests/Phpml/CrossValidation/RandomSplitTest.php b/tests/Phpml/CrossValidation/RandomSplitTest.php
index d31c6a6..74bfcd7 100644
--- a/tests/Phpml/CrossValidation/RandomSplitTest.php
+++ b/tests/Phpml/CrossValidation/RandomSplitTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\CrossValidation;
 
diff --git a/tests/Phpml/CrossValidation/StratifiedRandomSplitTest.php b/tests/Phpml/CrossValidation/StratifiedRandomSplitTest.php
index 14802de..afe3d81 100644
--- a/tests/Phpml/CrossValidation/StratifiedRandomSplitTest.php
+++ b/tests/Phpml/CrossValidation/StratifiedRandomSplitTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\CrossValidation;
 
diff --git a/tests/Phpml/Dataset/ArrayDatasetTest.php b/tests/Phpml/Dataset/ArrayDatasetTest.php
index d1ede5f..bd19bcb 100644
--- a/tests/Phpml/Dataset/ArrayDatasetTest.php
+++ b/tests/Phpml/Dataset/ArrayDatasetTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Dataset;
 
diff --git a/tests/Phpml/Dataset/CsvDatasetTest.php b/tests/Phpml/Dataset/CsvDatasetTest.php
index a2629a6..5a3546c 100644
--- a/tests/Phpml/Dataset/CsvDatasetTest.php
+++ b/tests/Phpml/Dataset/CsvDatasetTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Dataset;
 
diff --git a/tests/Phpml/Dataset/Demo/GlassDatasetTest.php b/tests/Phpml/Dataset/Demo/GlassDatasetTest.php
index 7ce3d37..b646c72 100644
--- a/tests/Phpml/Dataset/Demo/GlassDatasetTest.php
+++ b/tests/Phpml/Dataset/Demo/GlassDatasetTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Dataset\Demo;
 
diff --git a/tests/Phpml/Dataset/Demo/IrisDatasetTest.php b/tests/Phpml/Dataset/Demo/IrisDatasetTest.php
index 8e27db0..5bc4559 100644
--- a/tests/Phpml/Dataset/Demo/IrisDatasetTest.php
+++ b/tests/Phpml/Dataset/Demo/IrisDatasetTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Dataset\Demo;
 
diff --git a/tests/Phpml/Dataset/Demo/WineDatasetTest.php b/tests/Phpml/Dataset/Demo/WineDatasetTest.php
index cf6c53d..ee79d5b 100644
--- a/tests/Phpml/Dataset/Demo/WineDatasetTest.php
+++ b/tests/Phpml/Dataset/Demo/WineDatasetTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Dataset\Demo;
 
diff --git a/tests/Phpml/Dataset/FilesDatasetTest.php b/tests/Phpml/Dataset/FilesDatasetTest.php
index 5461c2f..f6e9555 100644
--- a/tests/Phpml/Dataset/FilesDatasetTest.php
+++ b/tests/Phpml/Dataset/FilesDatasetTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Dataset;
 
diff --git a/tests/Phpml/FeatureExtraction/StopWordsTest.php b/tests/Phpml/FeatureExtraction/StopWordsTest.php
index dfb5877..feed892 100644
--- a/tests/Phpml/FeatureExtraction/StopWordsTest.php
+++ b/tests/Phpml/FeatureExtraction/StopWordsTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\FeatureExtraction;
 
diff --git a/tests/Phpml/FeatureExtraction/TfIdfTransformerTest.php b/tests/Phpml/FeatureExtraction/TfIdfTransformerTest.php
index 116b608..fd9bb1c 100644
--- a/tests/Phpml/FeatureExtraction/TfIdfTransformerTest.php
+++ b/tests/Phpml/FeatureExtraction/TfIdfTransformerTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\FeatureExtraction;
 
diff --git a/tests/Phpml/FeatureExtraction/TokenCountVectorizerTest.php b/tests/Phpml/FeatureExtraction/TokenCountVectorizerTest.php
index 22ff1a9..2a49b87 100644
--- a/tests/Phpml/FeatureExtraction/TokenCountVectorizerTest.php
+++ b/tests/Phpml/FeatureExtraction/TokenCountVectorizerTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\FeatureExtraction;
 
diff --git a/tests/Phpml/Math/Distance/ChebyshevTest.php b/tests/Phpml/Math/Distance/ChebyshevTest.php
index 78fb2a0..c35432d 100644
--- a/tests/Phpml/Math/Distance/ChebyshevTest.php
+++ b/tests/Phpml/Math/Distance/ChebyshevTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Metric;
 
diff --git a/tests/Phpml/Math/Distance/EuclideanTest.php b/tests/Phpml/Math/Distance/EuclideanTest.php
index a3dea3c..b3a1f31 100644
--- a/tests/Phpml/Math/Distance/EuclideanTest.php
+++ b/tests/Phpml/Math/Distance/EuclideanTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Metric;
 
diff --git a/tests/Phpml/Math/Distance/ManhattanTest.php b/tests/Phpml/Math/Distance/ManhattanTest.php
index 7d0cf2d..07c6510 100644
--- a/tests/Phpml/Math/Distance/ManhattanTest.php
+++ b/tests/Phpml/Math/Distance/ManhattanTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Metric;
 
diff --git a/tests/Phpml/Math/Distance/MinkowskiTest.php b/tests/Phpml/Math/Distance/MinkowskiTest.php
index ad9318d..3e8afdb 100644
--- a/tests/Phpml/Math/Distance/MinkowskiTest.php
+++ b/tests/Phpml/Math/Distance/MinkowskiTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Metric;
 
diff --git a/tests/Phpml/Math/Kernel/RBFTest.php b/tests/Phpml/Math/Kernel/RBFTest.php
index 5b9bcb4..4eea13e 100644
--- a/tests/Phpml/Math/Kernel/RBFTest.php
+++ b/tests/Phpml/Math/Kernel/RBFTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace test\Phpml\Math\Kernel;
 
diff --git a/tests/Phpml/Math/MatrixTest.php b/tests/Phpml/Math/MatrixTest.php
index 64bb903..442ef0c 100644
--- a/tests/Phpml/Math/MatrixTest.php
+++ b/tests/Phpml/Math/MatrixTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Math;
 
diff --git a/tests/Phpml/Math/ProductTest.php b/tests/Phpml/Math/ProductTest.php
index fe53e9a..7fc525c 100644
--- a/tests/Phpml/Math/ProductTest.php
+++ b/tests/Phpml/Math/ProductTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Math;
 
diff --git a/tests/Phpml/Math/Statistic/CorrelationTest.php b/tests/Phpml/Math/Statistic/CorrelationTest.php
index 948dc16..c8c9fc6 100644
--- a/tests/Phpml/Math/Statistic/CorrelationTest.php
+++ b/tests/Phpml/Math/Statistic/CorrelationTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace test\Phpml\Math\StandardDeviation;
 
diff --git a/tests/Phpml/Math/Statistic/MeanTest.php b/tests/Phpml/Math/Statistic/MeanTest.php
index 805e6a7..5160f6b 100644
--- a/tests/Phpml/Math/Statistic/MeanTest.php
+++ b/tests/Phpml/Math/Statistic/MeanTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace test\Phpml\Math\StandardDeviation;
 
diff --git a/tests/Phpml/Math/Statistic/StandardDeviationTest.php b/tests/Phpml/Math/Statistic/StandardDeviationTest.php
index 299c979..59c72c2 100644
--- a/tests/Phpml/Math/Statistic/StandardDeviationTest.php
+++ b/tests/Phpml/Math/Statistic/StandardDeviationTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace test\Phpml\Math\StandardDeviation;
 
diff --git a/tests/Phpml/Metric/AccuracyTest.php b/tests/Phpml/Metric/AccuracyTest.php
index 436cb31..13a255a 100644
--- a/tests/Phpml/Metric/AccuracyTest.php
+++ b/tests/Phpml/Metric/AccuracyTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Metric;
 
diff --git a/tests/Phpml/Metric/ClassificationReportTest.php b/tests/Phpml/Metric/ClassificationReportTest.php
index 515f97c..bf9458d 100644
--- a/tests/Phpml/Metric/ClassificationReportTest.php
+++ b/tests/Phpml/Metric/ClassificationReportTest.php
@@ -1,12 +1,12 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Metric;
 
 use Phpml\Metric\ClassificationReport;
 
-class ClassificationReportTest extends  \PHPUnit_Framework_TestCase
+class ClassificationReportTest extends \PHPUnit_Framework_TestCase
 {
     public function testClassificationReportGenerateWithStringLabels()
     {
@@ -70,16 +70,15 @@ class ClassificationReportTest extends  \PHPUnit_Framework_TestCase
 
     public function testPreventDividedByZeroWhenPredictedLabelsAllNotMatch()
     {
-        $labels = [1,2,3,4,5];
-        $predicted = [2,3,4,5,6];
+        $labels = [1, 2, 3, 4, 5];
+        $predicted = [2, 3, 4, 5, 6];
 
         $report = new ClassificationReport($labels, $predicted);
 
         $this->assertEquals([
             'precision' => 0,
             'recall' => 0,
-            'f1score' => 0
+            'f1score' => 0,
         ], $report->getAverage(), '', 0.01);
     }
-
 }
diff --git a/tests/Phpml/Metric/ConfusionMatrixTest.php b/tests/Phpml/Metric/ConfusionMatrixTest.php
index d133ae2..1b2782b 100644
--- a/tests/Phpml/Metric/ConfusionMatrixTest.php
+++ b/tests/Phpml/Metric/ConfusionMatrixTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\Metric;
 
diff --git a/tests/Phpml/NeuralNetwork/ActivationFunction/BinaryStepTest.php b/tests/Phpml/NeuralNetwork/ActivationFunction/BinaryStepTest.php
index c074955..d749b12 100644
--- a/tests/Phpml/NeuralNetwork/ActivationFunction/BinaryStepTest.php
+++ b/tests/Phpml/NeuralNetwork/ActivationFunction/BinaryStepTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\NeuralNetwork\ActivationFunction;
 
diff --git a/tests/Phpml/NeuralNetwork/ActivationFunction/GaussianTest.php b/tests/Phpml/NeuralNetwork/ActivationFunction/GaussianTest.php
index 4780a53..40c7410 100644
--- a/tests/Phpml/NeuralNetwork/ActivationFunction/GaussianTest.php
+++ b/tests/Phpml/NeuralNetwork/ActivationFunction/GaussianTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\NeuralNetwork\ActivationFunction;
 
diff --git a/tests/Phpml/NeuralNetwork/ActivationFunction/HyperboliTangentTest.php b/tests/Phpml/NeuralNetwork/ActivationFunction/HyperboliTangentTest.php
index 92f4b97..039f33c 100644
--- a/tests/Phpml/NeuralNetwork/ActivationFunction/HyperboliTangentTest.php
+++ b/tests/Phpml/NeuralNetwork/ActivationFunction/HyperboliTangentTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\NeuralNetwork\ActivationFunction;
 
diff --git a/tests/Phpml/NeuralNetwork/ActivationFunction/SigmoidTest.php b/tests/Phpml/NeuralNetwork/ActivationFunction/SigmoidTest.php
index c84a20b..33c2fa4 100644
--- a/tests/Phpml/NeuralNetwork/ActivationFunction/SigmoidTest.php
+++ b/tests/Phpml/NeuralNetwork/ActivationFunction/SigmoidTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\NeuralNetwork\ActivationFunction;
 
diff --git a/tests/Phpml/NeuralNetwork/LayerTest.php b/tests/Phpml/NeuralNetwork/LayerTest.php
index 5706ab4..e39b3f7 100644
--- a/tests/Phpml/NeuralNetwork/LayerTest.php
+++ b/tests/Phpml/NeuralNetwork/LayerTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\NeuralNetwork;
 
diff --git a/tests/Phpml/NeuralNetwork/Network/LayeredNetworkTest.php b/tests/Phpml/NeuralNetwork/Network/LayeredNetworkTest.php
index 11fe914..1e18aea 100644
--- a/tests/Phpml/NeuralNetwork/Network/LayeredNetworkTest.php
+++ b/tests/Phpml/NeuralNetwork/Network/LayeredNetworkTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\NeuralNetwork\Network;
 
diff --git a/tests/Phpml/NeuralNetwork/Network/MultilayerPerceptronTest.php b/tests/Phpml/NeuralNetwork/Network/MultilayerPerceptronTest.php
index 1ac1621..0be25cd 100644
--- a/tests/Phpml/NeuralNetwork/Network/MultilayerPerceptronTest.php
+++ b/tests/Phpml/NeuralNetwork/Network/MultilayerPerceptronTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\NeuralNetwork\Network;
 
diff --git a/tests/Phpml/NeuralNetwork/Node/BiasTest.php b/tests/Phpml/NeuralNetwork/Node/BiasTest.php
index c0ece3f..121b387 100644
--- a/tests/Phpml/NeuralNetwork/Node/BiasTest.php
+++ b/tests/Phpml/NeuralNetwork/Node/BiasTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\NeuralNetwork\Node;
 
diff --git a/tests/Phpml/NeuralNetwork/Node/InputTest.php b/tests/Phpml/NeuralNetwork/Node/InputTest.php
index b0abdcc..8204f49 100644
--- a/tests/Phpml/NeuralNetwork/Node/InputTest.php
+++ b/tests/Phpml/NeuralNetwork/Node/InputTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\NeuralNetwork\Node;
 
diff --git a/tests/Phpml/NeuralNetwork/Node/Neuron/SynapseTest.php b/tests/Phpml/NeuralNetwork/Node/Neuron/SynapseTest.php
index 82560f1..6fbb555 100644
--- a/tests/Phpml/NeuralNetwork/Node/Neuron/SynapseTest.php
+++ b/tests/Phpml/NeuralNetwork/Node/Neuron/SynapseTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\NeuralNetwork\Node\Neuron;
 
diff --git a/tests/Phpml/NeuralNetwork/Node/NeuronTest.php b/tests/Phpml/NeuralNetwork/Node/NeuronTest.php
index 13bf6c5..06352c4 100644
--- a/tests/Phpml/NeuralNetwork/Node/NeuronTest.php
+++ b/tests/Phpml/NeuralNetwork/Node/NeuronTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\NeuralNetwork\Node;
 
diff --git a/tests/Phpml/NeuralNetwork/Training/BackpropagationTest.php b/tests/Phpml/NeuralNetwork/Training/BackpropagationTest.php
index 32deb64..30f633f 100644
--- a/tests/Phpml/NeuralNetwork/Training/BackpropagationTest.php
+++ b/tests/Phpml/NeuralNetwork/Training/BackpropagationTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Phpml\NeuralNetwork\Training;
 
diff --git a/tests/Phpml/PipelineTest.php b/tests/Phpml/PipelineTest.php
index 108a24c..73179f6 100644
--- a/tests/Phpml/PipelineTest.php
+++ b/tests/Phpml/PipelineTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests;
 
diff --git a/tests/Phpml/Preprocessing/ImputerTest.php b/tests/Phpml/Preprocessing/ImputerTest.php
index c607510..3e8e7d4 100644
--- a/tests/Phpml/Preprocessing/ImputerTest.php
+++ b/tests/Phpml/Preprocessing/ImputerTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Preprocessing;
 
diff --git a/tests/Phpml/Preprocessing/NormalizerTest.php b/tests/Phpml/Preprocessing/NormalizerTest.php
index d33881f..f29b6d5 100644
--- a/tests/Phpml/Preprocessing/NormalizerTest.php
+++ b/tests/Phpml/Preprocessing/NormalizerTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Preprocessing;
 
diff --git a/tests/Phpml/Regression/LeastSquaresTest.php b/tests/Phpml/Regression/LeastSquaresTest.php
index 8bd444f..c668b88 100644
--- a/tests/Phpml/Regression/LeastSquaresTest.php
+++ b/tests/Phpml/Regression/LeastSquaresTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Regression;
 
diff --git a/tests/Phpml/Regression/SVRTest.php b/tests/Phpml/Regression/SVRTest.php
index dd3518d..5f8bec9 100644
--- a/tests/Phpml/Regression/SVRTest.php
+++ b/tests/Phpml/Regression/SVRTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Regression;
 
diff --git a/tests/Phpml/SupportVectorMachine/DataTransformerTest.php b/tests/Phpml/SupportVectorMachine/DataTransformerTest.php
index c07948a..cb0ee52 100644
--- a/tests/Phpml/SupportVectorMachine/DataTransformerTest.php
+++ b/tests/Phpml/SupportVectorMachine/DataTransformerTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\SupportVectorMachine;
 
diff --git a/tests/Phpml/SupportVectorMachine/SupportVectorMachineTest.php b/tests/Phpml/SupportVectorMachine/SupportVectorMachineTest.php
index d14f777..4b4e03b 100644
--- a/tests/Phpml/SupportVectorMachine/SupportVectorMachineTest.php
+++ b/tests/Phpml/SupportVectorMachine/SupportVectorMachineTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\SupportVectorMachine;
 
diff --git a/tests/Phpml/Tokenization/WhitespaceTokenizerTest.php b/tests/Phpml/Tokenization/WhitespaceTokenizerTest.php
index 506abc1..8f2daf3 100644
--- a/tests/Phpml/Tokenization/WhitespaceTokenizerTest.php
+++ b/tests/Phpml/Tokenization/WhitespaceTokenizerTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Tokenization;
 
diff --git a/tests/Phpml/Tokenization/WordTokenizerTest.php b/tests/Phpml/Tokenization/WordTokenizerTest.php
index b7c7b37..959adfb 100644
--- a/tests/Phpml/Tokenization/WordTokenizerTest.php
+++ b/tests/Phpml/Tokenization/WordTokenizerTest.php
@@ -1,6 +1,6 @@
 <?php
 
-declare (strict_types = 1);
+declare(strict_types=1);
 
 namespace tests\Tokenization;