Merge pull request #19 from JvgRansika/add-sub-and-cross-product

add __sub__ and __rmul__

pymathzone/vector.py

@@ -37,11 +37,15 @@ def __add__(self, other):
         :return: vector
         """
         if isinstance(other, Vector):
-            pass
+            return Vector(addition(self, other))
         else:
             raise ValueError("Invalid addition!")
 
-        return Vector(addition(self, other))
+    def __sub__(self, other):
+        if isinstance(other, Vector):
+            return self.__add__(-1 * other)
+        else:
+            raise ValueError("Invalid subtraction!")
 
     def __eq__(self, other):
         if not isinstance(other, Vector):
@@ -57,14 +61,17 @@ def __mul__(self, other):
         else:
             raise Exception("Invalid multiplication")
 
+    def __rmul__(self, other):
+        return self.__mul__(other)
+
+
     def dot(self, other):
         if isinstance(other, int) or isinstance(other, float):
             return self.__mul__(other)
         elif isinstance(other, Vector):
-            return dot_multiplication_with_vector(self,other)
+            return dot_multiplication_with_vector(self, other)
         else:
             raise Exception("Invalid dot product")
 
-
     def get_dimension(self):
         return len(self.components)

tests/test_vector.py

@@ -34,6 +34,26 @@ def test_add_negative_vector(self):
         result = v1 + v2
         self.assertEqual(result.components, (0, 0, 0))
 
+    # subtraction
+    def test_subtraction_with_vector(self):
+        vector1 = Vector((5, 3))
+        vector2 = Vector((2, 1))
+        result = vector1 - vector2
+        expected = Vector((3, 2))
+        self.assertEqual(result, expected)
+
+    def test_subtraction_with_scalar(self):
+        vector = Vector((4, 2))
+        with self.assertRaises(ValueError) as context:
+            vector - 5
+        self.assertEqual(str(context.exception), "Invalid subtraction!")
+
+    def test_subtraction_with_invalid_type(self):
+        vector = Vector((1, 2))
+        with self.assertRaises(ValueError) as context:
+            vector - "hello"
+        self.assertEqual(str(context.exception), "Invalid subtraction!")
+
     def test_multiplication_with_scalar(self):
         vector = Vector((2, 3))
         result = vector * 2