new delete function for VTK

follows 'damask.Table' and makes GeomGrid.load_SPPARKS easier

python/damask/_vtk.py

@@ -457,7 +457,7 @@ class VTK:
             data: Union[None, np.ndarray, np.ma.MaskedArray] = None,
             info: Optional[str] = None,
             *,
-            table: Optional['Table'] = None):
+            table: Optional['Table'] = None) -> 'VTK':
         """
         Add new or replace existing point or cell data.
 
@@ -534,7 +534,6 @@ class VTK:
         else:
             raise TypeError
 
-
         return dup
 
 
@@ -581,6 +580,42 @@ class VTK:
             raise KeyError(f'array "{label}" not found')
 
 
+    def delete(self,
+               label: str) -> 'VTK':
+        """
+        Delete either cell or point data.
+
+        Cell data takes precedence over point data, i.e. this
+        function assumes that labels are unique among cell and
+        point data.
+
+        Parameters
+        ----------
+        label : str
+            Data label.
+
+        Returns
+        -------
+        updated : damask.VTK
+            Updated VTK-based geometry.
+
+        """
+        dup = self.copy()
+        cell_data = dup.vtk_data.GetCellData()
+        for a in range(cell_data.GetNumberOfArrays()):
+            if cell_data.GetArrayName(a) == label:
+                dup.vtk_data.GetCellData().RemoveArray(label)
+                return dup
+
+        point_data = self.vtk_data.GetPointData()
+        for a in range(point_data.GetNumberOfArrays()):
+            if point_data.GetArrayName(a) == label:
+                dup.vtk_data.GetPointData().RemoveArray(label)
+                return dup
+
+        raise KeyError(f'array "{label}" not found')
+
+
     def show(self,
              label: Optional[str] = None,
              colormap: Union[Colormap, str] = 'cividis'):

python/tests/test_GeomGrid.py

@@ -94,9 +94,9 @@ class TestGeomGrid:
 
     def test_save_load_SPPARKS(self,res_path,tmp_path):
         v = VTK.load(res_path/'SPPARKS_dump.vti')
-        v.set('material',v.get('spins')).save(tmp_path/'SPPARKS_dump.vti',parallel=False)
-        assert np.all(GeomGrid.load_SPPARKS(res_path/'SPPARKS_dump.vti').material == \
-                      GeomGrid.load(tmp_path/'SPPARKS_dump.vti').material)
+        v.set('material',v.get('spins')).delete('spins').save(tmp_path/'SPPARKS_dump.vti',parallel=False)
+        assert GeomGrid.load_SPPARKS(res_path/'SPPARKS_dump.vti') == \
+               GeomGrid.load(tmp_path/'SPPARKS_dump.vti')
 
     def test_invalid_origin(self,default):
         with pytest.raises(ValueError):

python/tests/test_VTK.py

@@ -199,6 +199,13 @@ class TestVTK:
         mask_manual = default.set('D',np.where(masked.mask,masked.fill_value,masked))
         assert mask_manual == mask_auto
 
+    @pytest.mark.parametrize('mode',['cells','points'])
+    def test_delete(self,default,mode):
+        data = np.random.rand(default.N_cells if mode == 'cells' else default.N_points).astype(np.float32)
+        v = default.set('D',data)
+        assert np.all(data == v.get('D'))
+        v = v.delete('D')
+        assert v == default
 
     @pytest.mark.parametrize('data_type,shape',[(float,(3,)),
                                                 (float,(3,3)),