refactor kmeans init methods

src/Phpml/Clustering/KMeans/Point.php

@@ -49,7 +49,7 @@ class Point implements ArrayAccess
             $distance  += $difference * $difference;
         }
 
-        return $precise ? sqrt((float)$distance) : $distance;
+        return $precise ? sqrt((float) $distance) : $distance;
     }
 
     /**

src/Phpml/Clustering/KMeans/Space.php

@@ -150,37 +150,11 @@ class Space extends SplObjectStorage
     {
         switch ($initMethod) {
             case KMeans::INIT_RANDOM:
-                list($min, $max) = $this->getBoundaries();
-                for ($n = 0; $n < $clustersNumber; ++$n) {
-                    $clusters[] = new Cluster($this, $this->getRandomPoint($min, $max)->getCoordinates());
-                }
+                $clusters = $this->initializeRandomClusters($clustersNumber);
                 break;
 
             case KMeans::INIT_KMEANS_PLUS_PLUS:
-                $position = rand(1, count($this));
-                for ($i = 1, $this->rewind(); $i < $position && $this->valid(); $i++, $this->next());
-                $clusters[] = new Cluster($this, $this->current()->getCoordinates());
-
-                $distances = new SplObjectStorage();
-
-                for ($i = 1; $i < $clustersNumber; ++$i) {
-                    $sum = 0;
-                    foreach ($this as $point) {
-                        $distance = $point->getDistanceWith($point->getClosest($clusters));
-                        $sum += $distances[$point] = $distance;
-                    }
-
-                    $sum = rand(0, (int) $sum);
-                    foreach ($this as $point) {
-                        if (($sum -= $distances[$point]) > 0) {
-                            continue;
-                        }
-
-                        $clusters[] = new Cluster($this, $point->getCoordinates());
-                        break;
-                    }
-                }
-
+                $clusters = $this->initializeKMPPClusters($clustersNumber);
                 break;
         }
         $clusters[0]->attachAll($this);
@@ -230,4 +204,56 @@ class Space extends SplObjectStorage
 
         return $convergence;
     }
+
+    /**
+     * @param int $clustersNumber
+     *
+     * @return array
+     */
+    private function initializeRandomClusters(int $clustersNumber)
+    {
+        $clusters = [];
+        list($min, $max) = $this->getBoundaries();
+
+        for ($n = 0; $n < $clustersNumber; ++$n) {
+            $clusters[] = new Cluster($this, $this->getRandomPoint($min, $max)->getCoordinates());
+        }
+
+        return $clusters;
+    }
+
+    /**
+     * @param int $clustersNumber
+     *
+     * @return array
+     */
+    protected function initializeKMPPClusters(int $clustersNumber)
+    {
+        $clusters = [];
+        $position = rand(1, count($this));
+        for ($i = 1, $this->rewind(); $i < $position && $this->valid(); $i++, $this->next());
+        $clusters[] = new Cluster($this, $this->current()->getCoordinates());
+
+        $distances = new SplObjectStorage();
+
+        for ($i = 1; $i < $clustersNumber; ++$i) {
+            $sum = 0;
+            foreach ($this as $point) {
+                $distance = $point->getDistanceWith($point->getClosest($clusters));
+                $sum += $distances[$point] = $distance;
+            }
+
+            $sum = rand(0, (int) $sum);
+            foreach ($this as $point) {
+                if (($sum -= $distances[$point]) > 0) {
+                    continue;
+                }
+
+                $clusters[] = new Cluster($this, $point->getCoordinates());
+                break;
+            }
+        }
+
+        return $clusters;
+    }
 }

src/Phpml/Math/Distance/Euclidean.php

@@ -30,6 +30,6 @@ class Euclidean implements Distance
             $distance += pow($a[$i] - $b[$i], 2);
         }
 
-        return sqrt((float)$distance);
+        return sqrt((float) $distance);
     }
 }

src/Phpml/Math/Matrix.php

@@ -147,7 +147,7 @@ class Matrix
             for ($j = 0; $j < $this->columns; ++$j) {
                 $subMatrix = $this->crossOut(0, $j);
                 $minor = $this->matrix[0][$j] * $subMatrix->getDeterminant();
-                $determinant += fmod((float)$j, 2.0) == 0 ? $minor : -$minor;
+                $determinant += fmod((float) $j, 2.0) == 0 ? $minor : -$minor;
             }
         }
 
@@ -236,7 +236,7 @@ class Matrix
         for ($i = 0; $i < $this->rows; ++$i) {
             for ($j = 0; $j < $this->columns; ++$j) {
                 $minor = $this->crossOut($i, $j)->getDeterminant();
-                $newMatrix[$i][$j] = fmod((float)($i + $j), 2.0) == 0 ? $minor : -$minor;
+                $newMatrix[$i][$j] = fmod((float) ($i + $j), 2.0) == 0 ? $minor : -$minor;
             }
         }
 

src/Phpml/Math/Statistic/Correlation.php

@@ -38,7 +38,7 @@ class Correlation
             $b2 = $b2 + pow($b, 2);
         }
 
-        $corr = $axb / sqrt((float)($a2 * $b2));
+        $corr = $axb / sqrt((float) ($a2 * $b2));
 
         return $corr;
     }

src/Phpml/Math/Statistic/StandardDeviation.php

@@ -39,6 +39,6 @@ class StandardDeviation
             --$n;
         }
 
-        return sqrt((float)($carry / $n));
+        return sqrt((float) ($carry / $n));
     }
 }