Resolve "Image creation bugs with 0 size windows"

Closes #21 (closed)

skais/process/basic_features_operations.py

@@ -18,16 +18,14 @@ def angular_dispersion(angles):
 
 def angular_mean(angles):
     x, y = angular_average_vector(angles)
-    theta = abs(np.arctan2(x, y))
+    theta = np.arctan(y/x)
 
-    if y > 0 and x > 0:  # first Q
+    if y > 0 and x > 0:
         return theta
-    if y > 0 >= x:  # Second Q
-        return np.pi / 2 + theta
-    if y <= 0 < x:  # Fourth Q
-        return np.pi / 2 - theta
-    else:  # Third Q
-        return - theta
+    elif x <= 0:
+        return np.pi + theta
+    else:
+        return 2*np.pi + theta
 
 
 def angular_std(angles):