(1) add negation and subtraction, (2) update readme

Author: hunan-rostomyan

README.md

@@ -1 +1,78 @@
-# abel
+# Vector
+
+```python
+from abel.linalg.vector import Vector
+
+a, b = Vector([1, 2]), Vector([3, 4])
+c, d = Vector([1, 2, 3]), Vector([4, 5, 6])
+
+assert a.shape == b.shape == (1, 2)
+assert c.shape == d.shape == (1, 3)
+```
+
+#### Addition
+
+```python
+assert a + a == Vector([2, 4])
+assert a + b == Vector([4, 6])
+assert b + b == Vector([6, 8])
+```
+
+#### Subtraction
+
+```python
+assert a - b == Vector([-2, -2])
+assert b - a == Vector([2, 2])
+```
+
+#### Scaling
+
+```python
+assert a * 5 == Vector([5, 10])
+assert 5 * a == Vector([5, 10])
+```
+
+#### Dot (inner) product
+
+```python
+assert a @ b == 11
+assert a @ a == 5
+```
+
+#### Norm (length)
+
+```python
+assert a.norm() - 2.236 < 0.001
+assert b.norm() - 5 < 0.001
+```
+
+#### Angle
+
+```python
+assert Vector.angle(a, a) < 0.001
+assert Vector.angle(a, b) - 0.1799 < 0.001
+assert Vector.angle(a, b) == Vector.angle(b, a)
+```
+
+#### Vector projection
+
+```python
+assert Vector.proj(a, a) == a
+assert Vector.proj(a, b) == Vector([1.32, 1.76])
+assert Vector.proj(b, a) == Vector([2.2, 4.4])
+```
+
+#### Scalar projection
+
+```python
+assert Vector.scalproj(a, b) - 4.919 < 0.01
+assert Vector.scalproj(b, a) - 2.2 < 0.01
+assert Vector.scalproj(a, a) - 2.236 < 0.01
+assert Vector.scalproj(b, b) - 5 < 0.1
+```
+
+#### Cross product
+
+```python
+assert Vector.cross(c, d) == Vector([-3, 6, -3])
+```

abel/linalg/test_vector.py

@@ -13,6 +13,13 @@ def test_add():
     assert a + b == Vector([4, 6])
     assert b + b == Vector([6, 8])
 
+def test_neg():
+    assert -a == -1 * a
+
+def test_sub():
+    assert a - b == a + (-b) == Vector([-2, -2])
+    assert b - a == b + (-a) == Vector([2, 2])
+
 def test_scal_mult():
     assert a * 5 == Vector([5, 10])
     assert 5 * a == Vector([5, 10])

abel/linalg/vector.py

@@ -17,11 +17,18 @@ def __repr__(self):
     def __eq__(self, other):
         return self._contents == other._contents
 
+    def __neg__(self):
+        return self * -1
+
     def __add__(self, B):
         """Vector addition."""
         xs, ys = self._contents, B._contents
         return Vector([x + ys[i] for i, x in enumerate(xs)])
 
+    def __sub__(self, B):
+        """Vector subtraction."""
+        return self + -B
+
     def __mul__(self, k):
         """Scalar multiplication."""
         return Vector([x * k for x in self._contents])

setup.py

@@ -5,7 +5,7 @@
 
 setuptools.setup(
     name='abel',
-    version='0.0.2',
+    version='0.0.3',
     author='Hunan Rostomyan',
     author_email='hunan131@gmail.com',
     description='Machine learning components',