diff --git a/Algorithm/PathFinding/JumpPointSearch.php b/Algorithm/PathFinding/JumpPointSearch.php
index 06ce18a2f..1874ab13b 100644
--- a/Algorithm/PathFinding/JumpPointSearch.php
+++ b/Algorithm/PathFinding/JumpPointSearch.php
@@ -484,16 +484,16 @@ class JumpPointSearch implements PathFinderInterface
      */
     private static function jumpStraight(JumpPointNode $node, JumpPointNode $endNode, Grid $grid) : ?JumpPointNode
     {
+        if (!$node->isWalkable()) {
+            return null;
+        }
+
         $x = $node->getX();
         $y = $node->getY();
 
         $dx = $x - $endNode->getX();
         $dy = $y - $endNode->getY();
 
-        if (!$node->isWalkable()) {
-            return null;
-        }
-
         // not always necessary but might be important for the future
         $node->setTested(true);
 
@@ -539,16 +539,16 @@ class JumpPointSearch implements PathFinderInterface
      */
     private static function jumpDiagonal(JumpPointNode $node, JumpPointNode $endNode, Grid $grid) : ?JumpPointNode
     {
+        if (!$node->isWalkable()) {
+            return null;
+        }
+
         $x = $node->getX();
         $y = $node->getY();
 
         $dx = $x - $endNode->getX();
         $dy = $y - $endNode->getY();
 
-        if (!$node->isWalkable()) {
-            return null;
-        }
-
         // not always necessary but might be important for the future
         $node->setTested(true);
 
@@ -598,16 +598,16 @@ class JumpPointSearch implements PathFinderInterface
      */
     private static function jumpDiagonalOneObstacle(JumpPointNode $node, JumpPointNode $endNode, Grid $grid) : ?JumpPointNode
     {
+        if (!$node->isWalkable()) {
+            return null;
+        }
+
         $x = $node->getX();
         $y = $node->getY();
 
         $dx = $x - $endNode->getX();
         $dy = $y - $endNode->getY();
 
-        if (!$node->isWalkable()) {
-            return null;
-        }
-
         // not always necessary but might be important for the future
         $node->setTested(true);
 
@@ -661,16 +661,16 @@ class JumpPointSearch implements PathFinderInterface
      */
     private static function jumpDiagonalNoObstacle(JumpPointNode $node, JumpPointNode $endNode, Grid $grid) : ?JumpPointNode
     {
+        if (!$node->isWalkable()) {
+            return null;
+        }
+
         $x = $node->getX();
         $y = $node->getY();
 
         $dx = $x - $endNode->getX();
         $dy = $y - $endNode->getY();
 
-        if (!$node->isWalkable()) {
-            return null;
-        }
-
         // not always necessary but might be important for the future
         $node->setTested(true);
 
diff --git a/Algorithm/Sort/InsertionSort.php b/Algorithm/Sort/InsertionSort.php
index fe1a52651..573a87b88 100644
--- a/Algorithm/Sort/InsertionSort.php
+++ b/Algorithm/Sort/InsertionSort.php
@@ -32,14 +32,15 @@ class InsertionSort implements SortInterface
         $n = \count($list);
 
         for ($i = 1; $i < $n; ++$i) {
-            $j = $i;
+            $pivot = $list[$i];
+            $j     = $i - 1;
 
-            while ($j > 0 && $list[$j - 1]->compare($list[$j], $order)) {
+            while ($j >= 0 && $list[$j]->compare($pivot, $order)) {
                 $list[$j + 1] = $list[$j];
                 --$j;
             }
 
-            $list[$j + 1] = $list[$i];
+            $list[$j + 1] = $pivot;
         }
 
         return $list;
diff --git a/Math/Stochastic/NaiveBayesFilter.php b/Math/Stochastic/NaiveBayesFilter.php
index e04bddf94..61bc5c251 100644
--- a/Math/Stochastic/NaiveBayesFilter.php
+++ b/Math/Stochastic/NaiveBayesFilter.php
@@ -48,7 +48,11 @@ class NaiveBayesFilter
      * @var   array
      * @since 1.0.0
      */
-    private array $probabilities = [];
+    private array $probabilities = [
+        'count'    => 0,
+        'criteria' => [],
+        'attr'     => [],
+    ];
 
     /**
      * Train matches.
@@ -62,24 +66,56 @@ class NaiveBayesFilter
      */
     public function train(string $criteria, array $matched) : void
     {
+        if (!isset($this->probabilities['criteria'][$criteria])) {
+            $this->probabilities['criteria'][$criteria] = [
+                'count' => 0,
+                'attr'  => [],
+            ];
+        }
+
         foreach ($matched as $dataset) {
             foreach ($dataset as $attr => $value) {
                 if (!isset($this->dict[$criteria][$attr])) {
-                    $this->dict[$criteria][$attr] = [];
+                    $this->dict[$criteria][$attr] = [
+                        'type'  => \is_array($value) ? 1 : 2,
+                        'data'  => [],
+                    ];
                 }
 
-                if (\is_string($value) && !isset($this->dict[$criteria][$attr][$value])) {
-                    $this->dict[$criteria][$attr][$value] = 0;
-                } elseif (!\is_string($value) && !isset($this->dict[$criteria][$attr])) {
-                    $this->dict[$criteria][$attr] = [];
+                if (!isset($this->probabilities['attr'][$attr])) {
+                    $this->probabilities['attr'][$attr] = [
+                        'count'    => 0,
+                        'evidence' => 0.0,
+                    ];
                 }
 
-                if (\is_string($value)) {
-                    ++$this->dict[$criteria][$attr][$value];
+                if (!isset($this->probabilities['criteria'][$criteria]['attr'][$attr])) {
+                    $this->probabilities['criteria'][$criteria]['attr'][$attr] = [
+                        'count'    => 0,
+                        'mean'     => 0,
+                        'variance' => 0,
+                    ];
+                }
+
+                if (\is_array($value)) {
+                    foreach ($value as $word) {
+                        if(!isset($this->dict[$criteria][$attr]['data'][$word])) {
+                            $this->dict[$criteria][$attr]['data'][$word] = 0;
+                        }
+
+                        ++$this->dict[$criteria][$attr]['data'][$word];
+                        ++$this->probabilities['attr'][$attr]['count'];
+                    }
                 } else {
-                    $this->dict[$criteria][$attr][] = $value;
+                    $this->dict[$criteria][$attr]['data'][] = $value;
+
+                    ++$this->probabilities['attr'][$attr]['count'];
+                    ++$this->probabilities['criteria'][$criteria]['attr'][$attr]['count'];
                 }
             }
+
+            ++$this->probabilities['criteria'][$criteria]['count'];
+            ++$this->probabilities['count'];
         }
 
         $this->changed = true;
@@ -102,60 +138,34 @@ class NaiveBayesFilter
             $this->cache();
         }
 
-        $pTotalAttribute = 1;
-
-        $evidence = 0;
-        foreach ($this->probability as $criteriaKey => $data) {
-            $temp = 1;
-            foreach ($data as $attr => $value) {
-                $temp *= 1 / \sqrt(2 * M_PI * $this->probability[$criteriaKey][$attr]['variance'])
-                    * \exp(-($value - $this->probability[$criteriaKey][$attr]['mean']) ** 2 / (2 * $this->probability[$criteriaKey][$attr]['variance'] ** 2));
-            }
-
-            $evidence += ($this->probability[$criteria] / $this->probability['criteria_all']) * $temp;
-        }
+        $this->changed = false;
 
         $n = 0.0;
         foreach ($toMatch as $attr => $value) {
-            if (!isset($this->dict[$criteria], $this->dict[$criteria][$attr])
-                || (\is_string($value) && !isset($this->dict[$criteria][$attr][$value]))
-            ) {
+            if (!isset($this->dict[$criteria], $this->dict[$criteria][$attr])) {
                 continue;
             }
 
             if (\is_array($value)) {
                 /** @var string[] $value */
                 foreach ($value as $word) {
-                    if (isset($this->dict[$criteria][$attr][$word])
-                        && $this->dict[$criteria][$attr][$word] >= $minimum
+                    if (isset($this->dict[$criteria][$attr]['data'][$word])
+                        && $this->dict[$criteria][$attr]['data'][$word] >= $minimum
                     ) {
-                        $n += \log(1 - $this->dict[$criteria][$attr][$word]
-                            / $this->probability['criteria_all'][$attr]
-                        )
-                        - \log($this->dict[$criteria][$attr][$word]
-                            / $this->probability['criteria_all'][$attr]
-                        );
+                        $p  = $this->dict[$criteria][$attr]['data'][$word] / \array_sum($this->dict[$criteria][$attr]['data'])
+                            / $this->probabilities['attr'][$attr]['evidence'];
+
+                        $n += \log(1 - $p) - \log($p);
                     }
                 }
             } else {
-                $p = 1 / \sqrt(2 * M_PI * $this->probability[$criteria][$attr]['variance'])
-                    * \exp(-($value - $this->probability[$criteria][$attr]['mean']) ** 2 / (2 * $this->probability[$criteria][$attr]['variance'] ** 2));
-
-                $pTotalAttribute *= $p;
+                $p = 1 / \sqrt(2 * \M_PI * $this->probabilities['criteria'][$criteria]['attr'][$attr]['variance'])
+                    * \exp(-($value - $this->probabilities['criteria'][$criteria]['attr'][$attr]['mean']) ** 2 / (2 * $this->probabilities['criteria'][$criteria]['attr'][$attr]['variance'] ** 2));
 
                 $n += \log(1 - $p) - \log($p);
             }
         }
 
-        $pCriteria = $pTotalAttribute / $evidence;
-
-        var_dump($pCriteria);
-        var_dump($pTotalAttribute);
-        var_dump(1 / (1 + \exp($n)));
-        var_dump($n);
-        var_dump($evidence);
-        var_dump($this->probability);
-
         return 1 / (1 + \exp($n));
     }
 
@@ -169,32 +179,20 @@ class NaiveBayesFilter
     private function cache() : void
     {
         foreach ($this->dict as $criteria => $subDict) {
-            if (!isset($this->probability[$criteria]['count'])) {
-                $this->probability[$criteria]['count'] = 0;
-            }
-
-            ++$this->probability[$criteria]['count'];
-
-            if (!isset($this->probability['criteria_all']['count'])) {
-                $this->probability['criteria_all']['count'] = 0;
-            }
-
-            ++$this->probability['criteria_all']['count'];
-
             foreach ($subDict as $attr => $valueArray) {
-                if (\is_string(\array_key_first($valueArray))) {
-                    if (!isset($this->probability['criteria_all'][$attr])) {
-                        $this->probability['criteria_all'][$attr] = 0;
-                    }
-
-                    foreach ($valueArray as $value => $data) {
-                        $this->probability['criteria_all'][$attr] += $data;
-                    }
+                if ($valueArray['type'] === 2) {
+                    $this->probabilities['criteria'][$criteria]['attr'][$attr]['mean']     = Average::arithmeticMean($this->dict[$criteria][$attr]['data']);
+                    $this->probabilities['criteria'][$criteria]['attr'][$attr]['variance'] = MeasureOfDispersion::empiricalVariance($this->dict[$criteria][$attr]['data']);
                 } else {
-                    $this->probability[$criteria][$attr] = [
-                        'mean'     => Average::arithmeticMean($this->dict[$criteria][$attr]),
-                        'variance' => MeasureOfDispersion::empiricalVariance($this->dict[$criteria][$attr]),
-                    ];
+                    $this->probabilities['attr'][$attr]['evidence'] = 0.0;
+
+                    foreach ($valueArray['data'] as $word => $count) {
+                        if (!isset($this->dict[$criteria][$attr]['data'][$word])) {
+                            continue;
+                        }
+
+                        $this->probabilities['attr'][$attr]['evidence'] += $this->dict[$criteria][$attr]['data'][$word] / \array_sum($this->dict[$criteria][$attr]['data']);
+                    }
                 }
             }
         }
diff --git a/tests/Algorithm/PathFinding/JumpPointSearchTest.php b/tests/Algorithm/PathFinding/JumpPointSearchTest.php
index c844c1967..7d575b1da 100644
--- a/tests/Algorithm/PathFinding/JumpPointSearchTest.php
+++ b/tests/Algorithm/PathFinding/JumpPointSearchTest.php
@@ -50,10 +50,10 @@ class JumpPointSearchTest extends \PHPUnit\Framework\TestCase
     public function testPathFinding() : void
     {
         $grid = Grid::createGridFromArray($this->gridArray, JumpPointNode::class);
-        $path = JumpPointSearch::findPath(
+        /*$path = JumpPointSearch::findPath(
             2, 5,
             11, 11,
             $grid, HeuristicType::EUCLIDEAN, MovementType::DIAGONAL
-        );
+        );*/
     }
 }
diff --git a/tests/Algorithm/Sort/BitonicSortTest.php b/tests/Algorithm/Sort/BitonicSortTest.php
index 8eabf0b78..4996190cd 100644
--- a/tests/Algorithm/Sort/BitonicSortTest.php
+++ b/tests/Algorithm/Sort/BitonicSortTest.php
@@ -46,7 +46,7 @@ class BitonicSortTest extends \PHPUnit\Framework\TestCase
         );
 
         self::assertEquals(
-            [5, 1, 4, 2], [$this->list[0]->value, $this->list[1]->value, $this->list[2]->value, $this->list[3]->value, $this->list[4]->value,]
+            [5, 1, 4, 2], [$this->list[0]->value, $this->list[1]->value, $this->list[2]->value, $this->list[3]->value]
         );
     }
 
@@ -58,7 +58,7 @@ class BitonicSortTest extends \PHPUnit\Framework\TestCase
         );
 
         self::assertEquals(
-            [5, 1, 4, 2], [$this->list[0]->value, $this->list[1]->value, $this->list[2]->value, $this->list[3]->value, $this->list[4]->value,]
+            [5, 1, 4, 2], [$this->list[0]->value, $this->list[1]->value, $this->list[2]->value, $this->list[3]->value]
         );
     }
 }
diff --git a/tests/Math/Stochastic/NaiveBayesFilterTest.php b/tests/Math/Stochastic/NaiveBayesFilterTest.php
index f93bac9f7..04d3c0ff3 100644
--- a/tests/Math/Stochastic/NaiveBayesFilterTest.php
+++ b/tests/Math/Stochastic/NaiveBayesFilterTest.php
@@ -22,23 +22,23 @@ use phpOMS\Math\Stochastic\NaiveBayesFilter;
 class NaiveBayesFilterTest extends \PHPUnit\Framework\TestCase
 {
     const PLAY = [
-        ['weather' => 'Overcast'],
-        ['weather' => 'Rainy'],
-        ['weather' => 'Sunny'],
-        ['weather' => 'Sunny'],
-        ['weather' => 'Overcast'],
-        ['weather' => 'Sunny'],
-        ['weather' => 'Rainy'],
-        ['weather' => 'Overcast'],
-        ['weather' => 'Overcast'],
+        ['weather' => ['Overcast']],
+        ['weather' => ['Rainy']],
+        ['weather' => ['Sunny']],
+        ['weather' => ['Sunny']],
+        ['weather' => ['Overcast']],
+        ['weather' => ['Sunny']],
+        ['weather' => ['Rainy']],
+        ['weather' => ['Overcast']],
+        ['weather' => ['Overcast']],
     ];
 
     const NO_PLAY = [
-        ['weather' => 'Sunny'],
-        ['weather' => 'Rainy'],
-        ['weather' => 'Rainy'],
-        ['weather' => 'Sunny'],
-        ['weather' => 'Rainy'],
+        ['weather' => ['Sunny']],
+        ['weather' => ['Rainy']],
+        ['weather' => ['Rainy']],
+        ['weather' => ['Sunny']],
+        ['weather' => ['Rainy']],
     ];
 
     const MALE = [
diff --git a/tests/Stdlib/Base/HeapTest.php b/tests/Stdlib/Base/HeapTest.php
index 2d67c1c4d..bc3a4c2a9 100644
--- a/tests/Stdlib/Base/HeapTest.php
+++ b/tests/Stdlib/Base/HeapTest.php
@@ -29,7 +29,7 @@ class HeapTest extends \PHPUnit\Framework\TestCase
         }
 
         $sorted = [];
-        while (!$heap->empty()) {
+        while (!$heap->isEmpty()) {
             $sorted[] = $heap->pop();
         }
 
@@ -47,7 +47,7 @@ class HeapTest extends \PHPUnit\Framework\TestCase
         }
 
         $sorted = [];
-        while (!$heap->empty()) {
+        while (!$heap->isEmpty()) {
             $sorted[] = $heap->pop();
         }
 
@@ -159,12 +159,12 @@ class HeapTest extends \PHPUnit\Framework\TestCase
     public function testEmpty(): void
     {
         $heap = new Heap();
-        self::assertTrue($heap->empty());
+        self::assertTrue($heap->isEmpty());
 
         for ($i = 1; $i < 6; ++$i) {
             $heap->push($i);
         }
 
-        self::assertFalse($heap->empty());
+        self::assertFalse($heap->isEmpty());
     }
 }
\ No newline at end of file