#28: Add concatenateRight and concatenateBottom.

Author: mcordingley

src/Matrix.php

@@ -130,6 +130,50 @@ public function adjoint()
         return $this->inverse()->multiply($this->determinant());
     }
 
+    /**
+     * @param Matrix $other
+     * @return Matrix
+     * @throws MatrixException
+     */
+    public function contatenateBottom(Matrix $other)
+    {
+        if ($this->columnCount !== $other->columnCount) {
+            throw new MatrixException(
+                'Cannot concatenate matrices of incompatible size: '
+                . print_r($this->internal, true)
+                . ' and '
+                . print_r($other->internal, true)
+            );
+        }
+
+        return new Matrix(array_merge($this->internal, $other->internal));
+    }
+
+    /**
+     * @param Matrix $other
+     * @return Matrix
+     * @throws MatrixException
+     */
+    public function contatenateRight(Matrix $other)
+    {
+        if ($this->rowCount !== $other->rowCount) {
+            throw new MatrixException(
+                'Cannot concatenate matrices of incompatible size: '
+                . print_r($this->internal, true)
+                . ' and '
+                . print_r($other->internal, true)
+            );
+        }
+
+        $concatenated = [];
+
+        for ($i = 0; $i < $this->rowCount; $i++) {
+            $concatenated[] = array_merge($this->internal[$i], $other->internal[$i]);
+        }
+
+        return new Matrix($concatenated);
+    }
+
     /**
      * @return float The matrix's determinant
      * @throws MatrixException

tests/MatrixTest.php

@@ -332,6 +332,31 @@ public function testAdjoint()
         $this->assertEquals(4, $adjoint->get(2, 2));
     }
 
+    public function testConcatenateBottom()
+    {
+        $matrixA = new Matrix([[1, 2, 3]]);
+        $matrixB = new Matrix([[4, 5, 6]]);
+        $concatenated = $matrixA->contatenateBottom($matrixB);
+
+        $this->assertEquals([
+            [1, 2, 3],
+            [4, 5, 6],
+        ], $concatenated->toArray());
+    }
+
+    public function testConcatenateRight()
+    {
+        $matrixA = new Matrix([[1], [2], [3]]);
+        $matrixB = new Matrix([[4], [5], [6]]);
+        $concatenated = $matrixA->contatenateRight($matrixB);
+
+        $this->assertEquals([
+            [1, 4],
+            [2, 5],
+            [3, 6],
+        ], $concatenated->toArray());
+    }
+
     public function testDeterminant()
     {
         $matrix = new Matrix([