angular mean fixed

skais/stats/angluar.py

@@ -18,13 +18,13 @@ def angular_mean(x):
 
     theta = abs(np.arctan2(X, Y))
 
-    if Y > 0 and X > 0:
+    if Y > 0 and X > 0: # first Q
         return theta
 
-    if Y > 0 >= X:
-        return np.pi/2 - theta
+    if Y > 0 >= X: # Second Q
+        return np.pi/2 + theta
 
-    if Y <= 0 < X:
-        return np.pi + theta
-    else:
-        return 2 * np.pi + theta
+    if Y <= 0 < X: # Fourth Q
+        return np.pi/2 - theta
+    else: #Third Q
+        return - theta

skais/tests/stats/test_angular.py

@@ -34,9 +34,9 @@ class TestAngular(unittest.TestCase):
     def test_angular_mean_third_quadrant(self):
         x = np.radians(np.array([223, 224, 225, 226, 227]))
 
-        self.assertEqual(5*np.pi / 4, angular_mean(x))
+        self.assertEqual(-3*np.pi / 4, angular_mean(x))
 
     def test_angular_mean_fourth_quadrant(self):
         x = np.radians(np.array([313, 314, 315, 316, 317]))
 
-        self.assertEqual(7*np.pi / 4, angular_mean(x))
+        self.assertEqual(-np.pi / 4, angular_mean(x))