Inspection and output

Plotting and export methods live on the Morana object that owns the data being inspected. Maintained examples write generated artifacts under artifacts/examples/ by default.

Morana’s lightweight serializer writes VTU and VTM output directly as VTK XML, so export does not require the Python vtk package. The development environment includes vtk only to reopen generated files with an independent reader during testing. ParaView and Python VTK are optional tools for interactive inspection and downstream processing.

Planar mesh

HexPlanarMesh provides plot_matplotlib(), to_plotly(), and export_vtu(path) for the full regular lattice with planar IDs, lattice coordinates, and OpenMC ring-position indices. The official VTK XML format documentation defines .vtu as the serial UnstructuredGrid format and describes its point, cell, and data-array structure.

The planar VTU cell arrays are planar_id, lattice_x, lattice_u, openmc_ring, and openmc_position.

Material layout

MaterialMesh provides plot_matplotlib(axial_index, materials) and to_plotly(axial_index, materials) for one selected axial slice, and export_vtm(path) for true hexagonal-prism cells in separate active and excluded leaf datasets. VTK’s vtkXMLMultiBlockDataWriter reference describes the corresponding multiblock writer and its recursively written child datasets. For layout.vtm, Morana creates the referenced layout/active.vtu and layout/excluded.vtu leaves. That directory also contains material_keys.json, which maps material_key_id values to their original material keys. Repeated exports replace these stable files; keep the index and its directory together.

For material-layout plots, excluded-region colors take precedence. The built-in inactive key "0" is white; a custom region uses its configured ExcludedRegion.color or the default light-gray #d9d9d9. Active keys use the explicit Material.color supplied through materials when present; all other active keys receive the repeating default palette in first-use order, scanning layers bottom-to-top and positions in planar order. Call MaterialMesh.material_colors() to inspect the resolved mapping used by both plotting backends.

Both leaves contain these cell arrays:

Array	Meaning
planar_id	Full-lattice planar ID
active_id	Slice-local active ID, or NaN for an excluded cell
axial_index	Bottom-to-top layer index
domain_group_id	1 for active cells and 0 for excluded cells
material_key_id	Deterministic integer ID assigned on first encounter, scanning layers bottom-to-top and cells in planar order
lattice_x, lattice_u	Integer lattice coordinates
openmc_ring, openmc_position	OpenMC-style serialized position

Plotting conventions

All Matplotlib and Plotly hex plots use black cell edges, Cartesian axis labels, and equal aspect ratio. Plotly also provides per-cell hover labels.

Plotly renders visible hexagons in batched Cartesian Scatter traces grouped by fill color and, for material layouts, legend group. A transparent hex-marker overlay supplies the per-cell hover target and remains available while zooming. Material legend toggles hide both the visible region and its matching hover targets. Plotly hex figures use a fixed initial canvas so these pixel-sized hover markers align with the cells.

Result flux is compact over active cells. When it is mapped onto the full planar lattice, excluded positions contain NaN. Both plotting backends render those positions with the fixed light-gray color #d9d9d9. This color is outside the scalar-flux colormap and means “no solver value,” not zero flux. Finite scalar flux uses the centralized inferno colormap in both backends.

Solver results

Result provides plot_matplotlib(group, axial_index) and plot_plotly(group, axial_index) for a selected scalar-flux slice using the conventions above.

For one active planar position, result.cell_at(axial_index, openmc_index) returns a read-only CellInspection value with its material key, cross sections, and complete fast-to-thermal flux vector without exposing the layer-local compact cell ID. Obtain this value through cell_at(); direct construction is not supported.

Result.export_vtm("solution.vtm") writes material-aware active and excluded blocks with the material-layout arrays above and one flux_gN field per energy group, numbered from fast to thermal beginning at flux_g0. Excluded-cell flux fields contain NaN. Its solution/material_keys.json maps each material_key_id value to its original material key. Open the VTM file in ParaView and use View → MultiBlock Inspector to toggle blocks, as described in the official ParaView MultiBlock documentation.

The geometry guide defines the IDs and axial ordering preserved by these outputs. See the maintained examples for runnable output workflows, the result archive guide for completed result persistence, and the Python reference for exact method signatures.