add euclidean distance and similarity function in vector class (#36)

* add set function in Matrix Class

* remove set function in Matrix Class

* change namespace and add strict_type in VectorTest class

* add magnitude function in Vector Class

* add cosine similarity function in vector class

* add euclidean distance and similarity function in vector class

Co-authored-by: 권욱진 <[email protected]>
Co-authored-by: battlecook <[email protected]>

Author: 3 people

src/Vector.php

@@ -97,6 +97,28 @@ public function cosineSimilarity(self $other): float
         return $this->dotProduct($other) / ($this->l2Norm() * $other->l2Norm());
     }
 
+    /**
+     * @param self $other
+     * @return float
+     * @throws VectorException
+     * @link https://en.wikipedia.org/wiki/Euclidean_distance
+     */
+    public function euclideanDistance(self $other): float
+    {
+        return sqrt(array_sum(array_map(
+            function (float $a, float $b) {
+                return pow($a - $b, 2);
+            },
+            $this->toArray(),
+            $other->toArray()
+        )));
+    }
+
+    public function euclideanSimilarity(self $other): float
+    {
+        return $this->euclideanDistance($other);
+    }
+
     /**
      * @param self $other
      * @return float

tests/VectorTest.php

@@ -114,6 +114,22 @@ public function testCosineSimilarity()
         $this->assertEquals(1.00, $vector1->cosineSimilarity($vector2));
     }
 
+    public function testEuclideanDistance()
+    {
+        $vector1 = new Vector([-1, 2, 3]);
+        $vector2 = new Vector([4, 0, -3]);
+
+        $this->assertEquals(8.06225774829855, $vector1->euclideanDistance($vector2));
+    }
+
+    public function testEuclideanSimilarity()
+    {
+        $vector1 = new Vector([-1, 2, 3]);
+        $vector2 = new Vector([4, 0, -3]);
+
+        $this->assertEquals(8.06225774829855, $vector1->euclideanSimilarity($vector2));
+    }
+
     public function testOuterProduct()
     {
         $vector1 = new Vector([1, 2]);