Change comparison of Quantity (to fix python-quantitiesgh-146)

quantities/quantity.py

@@ -375,43 +375,48 @@ def __setitem__(self, key, value):
             value = value.rescale(self._dimensionality)
         self.magnitude[key] = value
 
+    def _magnitude_of_other(self, other):
+        if not isinstance(other, Quantity):
+            other = other * unit_registry['dimensionless']
+        return other.rescale(self._dimensionality).magnitude
+
     @with_doc(np.ndarray.__lt__)
     @wrap_comparison
     def __lt__(self, other):
-        return self.magnitude < other
+        return self.magnitude < self._magnitude_of_other(other)
 
     @with_doc(np.ndarray.__le__)
     @wrap_comparison
     def __le__(self, other):
-        return self.magnitude <= other
+        return self.magnitude <= self._magnitude_of_other(other)
 
     @with_doc(np.ndarray.__eq__)
     def __eq__(self, other):
-        if isinstance(other, Quantity):
-            try:
-                other = other.rescale(self._dimensionality).magnitude
-            except ValueError:
-                return np.zeros(self.shape, '?')
-        return self.magnitude == other
+        try:
+            other_mag = self._magnitude_of_other(other)
+        except ValueError:
+            return np.zeros(self.shape, '?')
+        else:
+            return self.magnitude == other_mag
 
     @with_doc(np.ndarray.__ne__)
     def __ne__(self, other):
-        if isinstance(other, Quantity):
-            try:
-                other = other.rescale(self._dimensionality).magnitude
-            except ValueError:
-                return np.ones(self.shape, '?')
-        return self.magnitude != other
+        try:
+            other_mag = self._magnitude_of_other(other)
+        except ValueError:
+            return np.ones(self.shape, '?')
+        else:
+            return self.magnitude != other_mag
 
     @with_doc(np.ndarray.__ge__)
     @wrap_comparison
     def __ge__(self, other):
-        return self.magnitude >= other
+        return self.magnitude >= self._magnitude_of_other(other)
 
     @with_doc(np.ndarray.__gt__)
     @wrap_comparison
     def __gt__(self, other):
-        return self.magnitude > other
+        return self.magnitude > self._magnitude_of_other(other)
 
     #I don't think this implementation is particularly efficient,
     #perhaps there is something better

quantities/tests/test_comparison.py

@@ -19,6 +19,8 @@ def test_scalar_equality(self):
         self.assertEqual(pq.J == 2*pq.kg*pq.m**2/pq.s**2, [False])
 
         self.assertEqual(pq.J == pq.kg, [False])
+        self.assertTrue(1e3*pq.m == pq.km)
+        self.assertFalse(1e3*pq.m == [1e3])
 
     def test_scalar_inequality(self):
         self.assertEqual(pq.J != pq.erg, [True])
@@ -66,7 +68,7 @@ def test_array_equality(self):
         )
         self.assertQuantityEqual(
             [1, 2, 3, 4]*pq.J == [1, 22, 3, 44],
-            [1, 0, 1, 0]
+            [0, 0, 0, 0]
         )
 
     def test_array_inequality(self):
@@ -80,7 +82,7 @@ def test_array_inequality(self):
         )
         self.assertQuantityEqual(
             [1, 2, 3, 4]*pq.J != [1, 22, 3, 44],
-            [0, 1, 0, 1]
+            [1, 1, 1, 1]
         )
 
     def test_quantity_less_than(self):
@@ -92,9 +94,11 @@ def test_quantity_less_than(self):
             [50, 100, 150]*pq.cm < [1, 1, 1]*pq.m,
             [1, 0, 0]
         )
-        self.assertQuantityEqual(
-            [1, 2, 33]*pq.J < [1, 22, 3],
-            [0, 1, 0]
+        self.assertRaises(
+            ValueError,
+            op.lt,
+            [1, 2, 33]*pq.J,
+            [1, 22, 3]
         )
         self.assertRaises(
             ValueError,
@@ -112,9 +116,11 @@ def test_quantity_less_than_or_equal(self):
             [50, 100, 150]*pq.cm <= [1, 1, 1]*pq.m,
             [1, 1, 0]
         )
-        self.assertQuantityEqual(
-            [1, 2, 33]*pq.J <= [1, 22, 3],
-            [1, 1, 0]
+        self.assertRaises(
+            ValueError,
+            op.le,
+            [1, 2, 33]*pq.J,
+            [1, 22, 3]
         )
         self.assertRaises(
             ValueError,
@@ -132,9 +138,11 @@ def test_quantity_greater_than_or_equal(self):
             [50, 100, 150]*pq.cm >= [1, 1, 1]*pq.m,
             [0, 1, 1]
         )
-        self.assertQuantityEqual(
-            [1, 2, 33]*pq.J >= [1, 22, 3],
-            [1, 0, 1]
+        self.assertRaises(
+            ValueError,
+            op.ge,
+            [1, 2, 33]*pq.J,
+            [1, 22, 3]
         )
         self.assertRaises(
             ValueError,
@@ -152,9 +160,11 @@ def test_quantity_greater_than(self):
             [50, 100, 150]*pq.cm > [1, 1, 1]*pq.m,
             [0, 0, 1]
         )
-        self.assertQuantityEqual(
-            [1, 2, 33]*pq.J > [1, 22, 3],
-            [0, 0, 1]
+        self.assertRaises(
+            ValueError,
+            op.gt,
+            [1, 2, 33]*pq.J,
+            [1, 22, 3]
         )
         self.assertRaises(
             ValueError,