.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "example_gallery/auto_examples/basic/cell_volumes.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_example_gallery_auto_examples_basic_cell_volumes.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_example_gallery_auto_examples_basic_cell_volumes.py:


Compute cell volumes on a volume mesh
=====================================

This tutorial computes per-cell volumes on a small volume mesh and compares
their sum with PyVista's total volume. Use this example when you want the
simplest geometry calculation on a ``TensorMesh``.

.. GENERATED FROM PYTHON SOURCE LINES 11-13

Imports
-------

.. GENERATED FROM PYTHON SOURCE LINES 13-20

.. code-block:: Python

    import numpy as np
    import pyvista as pv
    import torch

    import graphlow









.. GENERATED FROM PYTHON SOURCE LINES 21-23

Step 1: Build a small volume mesh
---------------------------------

.. GENERATED FROM PYTHON SOURCE LINES 23-34

.. code-block:: Python

    def make_volume_grid() -> pv.UnstructuredGrid:
        """Create a small warped hexahedral grid."""
        x = np.array([0.0, 1.0, 2.2, 3.5], dtype=np.float32)
        y = np.array([0.0, 0.8, 1.7], dtype=np.float32)
        z = np.array([0.0, 0.6, 1.4], dtype=np.float32)
        X, Y, Z = np.meshgrid(x, y, z, indexing="ij")
        Z = Z + 0.12 * X * Y
        grid = pv.StructuredGrid(X, Y, Z)
        return grid.cast_to_unstructured_grid()









.. GENERATED FROM PYTHON SOURCE LINES 35-37

Step 2: Compute cell volumes
----------------------------

.. GENERATED FROM PYTHON SOURCE LINES 37-65

.. code-block:: Python

    def main() -> None:
        """Run the tutorial."""
        mesh = graphlow.from_pyvista(make_volume_grid(), backend="torch")
        cell_volumes = mesh.geometry.cell_volumes()
        total_volume = torch.sum(cell_volumes).item()

        print(f"Cell volume tensor shape: {tuple(cell_volumes.shape)}")
        print(f"First four cell volumes: {cell_volumes[:4, 0].tolist()}")
        print(f"Total volume from graphlow: {total_volume:.6f}")
        print(f"Total volume from PyVista: {mesh.pvmesh.volume:.6f}")

        mesh.cell_data["cell_volume"] = cell_volumes
        mesh.copy_features_to_pyvista()

        plotter = pv.Plotter(window_size=[800, 600])
        plotter.add_mesh(
            mesh.pvmesh,
            scalars="cell_volume",
            show_edges=True,
            cmap="viridis",
        )
        plotter.show_bounds(mesh=mesh.pvmesh, location="outer")
        plotter.camera_position = "iso"
        plotter.show()


    if __name__ == "__main__":
        main()



.. image-sg:: /example_gallery/auto_examples/basic/images/sphx_glr_cell_volumes_001.png
   :alt: cell volumes
   :srcset: /example_gallery/auto_examples/basic/images/sphx_glr_cell_volumes_001.png
   :class: sphx-glr-single-img


.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    Cell volume tensor shape: (12, 1)
    First four cell volumes: [0.4800001084804535, 0.5760000348091125, 0.6240000128746033, 0.5400000214576721]
    Total volume from graphlow: 8.330000
    Total volume from PyVista: 8.330000





.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 0.370 seconds)


.. _sphx_glr_download_example_gallery_auto_examples_basic_cell_volumes.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: cell_volumes.ipynb <cell_volumes.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: cell_volumes.py <cell_volumes.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: cell_volumes.zip <cell_volumes.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_