Move save to io

skfem/io/meshio.py

@@ -17,6 +17,8 @@
     ('line', skfem.MeshLine),
 ])
 
+TYPE_MESH_MAPPING = {v: k for k, v in MESH_TYPE_MAPPING.items()}
+
 
 def from_meshio(m, force_mesh_type=None):
     """Convert meshio mesh into :class:`skfem.mesh.Mesh`.
@@ -130,3 +132,12 @@ def find_tagname(tag):
 
 def from_file(filename):
     return from_meshio(meshio.read(filename))
+
+
+def to_meshio(mesh, point_data=None):
+    cells = {TYPE_MESH_MAPPING[type(mesh)]: mesh.t.T}
+    return meshio.Mesh(mesh.p.T, cells, point_data)
+
+
+def to_file(mesh, filename, point_data=None, **kwargs):
+    meshio.write(filename, to_meshio(mesh, point_data), **kwargs)

skfem/mesh/mesh.py

@@ -244,8 +244,7 @@ def _validate(self):
 
     def save(self,
              filename: str,
-             point_data: Optional[Dict[str, ndarray]] = None,
-             cell_data: Optional[Dict[str, ndarray]] = None,
+             point_data: Dict[str, ndarray] = None,
              **kwargs) -> None:
         """Export the mesh and fields using meshio.
 
@@ -256,26 +255,10 @@ def save(self,
             e.g. .msh, .vtk, .xdmf
         point_data
             Data related to the vertices of the mesh.
-        cell_data
-            Data related to the elements of the mesh.
 
         """
-        import meshio
-
-        if point_data is not None:
-            if not isinstance(point_data, dict):
-                raise ValueError("point_data should be "
-                                 "a dictionary of ndarrays.")
-
-        if cell_data is not None:
-            if not isinstance(cell_data, dict):
-                raise ValueError("cell_data should be "
-                                 "a dictionary of ndarrays.")
-            cell_data = {self.meshio_type: cell_data}
-
-        cells = {self.meshio_type: self.t.T}
-        mesh = meshio.Mesh(self.p.T, cells, point_data, cell_data)
-        meshio.write(filename, mesh, **kwargs)
+        from skfem.io.meshio import to_file
+        return to_file(self, filename, point_data, **kwargs)
 
     @classmethod
     def from_basis(cls: Type[MeshType], basis):

skfem/utils.py

@@ -317,7 +317,7 @@ def funv(v, dv, w):
 
     @bilinear_form
     def deriv(u, du, v, dv, w):
-        return du[i] * v
+        return du[diff] * v
 
     M = asm(mass, basis_to)