Class VTXWriter

python/dolfinx/io/utils.py:34–113

Writer for VTX files, using ADIOS2 to create the files. VTX supports arbitrary order Lagrange finite elements for the geometry description and arbitrary order (discontinuous) Lagrange finite elements for Functions. The files can be viewed using Paraview.

    __all__ = [*__all__, "VTXWriter", "VTXMeshPolicy"]

    class VTXWriter:
        """Writer for VTX files, using ADIOS2 to create the files.

        VTX supports arbitrary order Lagrange finite elements for the
        geometry description and arbitrary order (discontinuous)
        Lagrange finite elements for Functions.

        The files can be viewed using Paraview.
        """

        _cpp_object: _cpp.io.VTXWriter_float32 | _cpp.io.VTXWriter_float64

        def __init__(
            self,
            comm: _MPI.Comm,
            filename: str | Path,
            output: Mesh | Function | list[Function] | tuple[Function],
            engine: str = "BPFile",
            mesh_policy: VTXMeshPolicy = VTXMeshPolicy.update,
        ):
            """Initialize a writer for outputting data in the VTX format.

            Args:
                comm: The MPI communicator
                filename: The output filename
                output: The data to output. Either a mesh, a single
                    (discontinuous) Lagrange Function or list of
                    (discontinuous) Lagrange Functions.
                engine: ADIOS2 engine to use for output. See
                    ADIOS2 documentation for options.
                mesh_policy: Controls if the mesh is written to file at
                    the first time step only when a ``Function`` is
                    written to file, or is re-written (updated) at each
                    time step. Has an effect only for ``Function``
                    output.

            Note:
                All Functions for output must share the same mesh and
                have the same element type.
            """
            # Get geometry type
            if isinstance(output, Mesh):
                dtype = output.geometry.x.dtype
            elif isinstance(output, Function):
                dtype = output.function_space.mesh.geometry.x.dtype
            else:
                dtype = output[0].function_space.mesh.geometry.x.dtype

            if np.issubdtype(dtype, np.float32):
                _vtxwriter = _cpp.io.VTXWriter_float32
            elif np.issubdtype(dtype, np.float64):
                _vtxwriter = _cpp.io.VTXWriter_float64
            else:
                raise RuntimeError(f"VTXWriter does not support dtype={dtype}.")

            if isinstance(output, Mesh):
                self._cpp_object = _vtxwriter(comm, filename, output._cpp_object, engine)  # type: ignore[union-attr]
            else: