fix for broken representation of no-rotation orientations and averaging weights

python/damask/_orientation.py

@@ -226,9 +226,9 @@ class Orientation(Rotation):
 
         """
         return  super().__eq__(other) \
-            and self.family     == other.family \
-            and self.lattice    == other.lattice \
-            and self.parameters == other.parameters
+            and hasattr(other, 'family')     and self.family     == other.family \
+            and hasattr(other, 'lattice')    and self.lattice    == other.lattice \
+            and hasattr(other, 'parameters') and self.parameters == other.parameters
 
 
     def __matmul__(self,other):

python/damask/_rotation.py

@@ -204,8 +204,16 @@ class Rotation:
 
 
     def append(self,other):
-        """Extend rotation array along first dimension with other array."""
-        return self.copy(rotation=np.vstack((self.quaternion,other.quaternion)))
+        """
+        Extend rotation array along first dimension with other array(s).
+
+        Parameters
+        ----------
+            other : Rotation or list of Rotations.
+
+        """
+        return self.copy(rotation=np.vstack(tuple(map(lambda x:x.quaternion,
+                                                      [self]+other if type(other) == list else [self,other]))))
 
 
     def flatten(self,order = 'C'):
@@ -263,7 +271,7 @@ class Rotation:
             """Intermediate representation supporting quaternion averaging."""
             return np.einsum('...i,...j',quat,quat)
 
-        if not weights:
+        if weights is None:
             weights = np.ones(self.shape,dtype=float)
 
         eig, vec = np.linalg.eig(np.sum(_M(self.quaternion) * weights[...,np.newaxis,np.newaxis],axis=-3) \