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

.. only:: html

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

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

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

.. _sphx_glr_auto_how_to_example_sample_line.py:


Sample a field along a line
===========================

``line(mesh, name, start, end, n_points, field_name)`` builds a
``PointDataSet`` with the requested field already interpolated onto evenly
spaced points between ``start`` and ``end``. This is the pyOFTools-side
equivalent of OpenFOAM's ``uniform`` set in ``system/sampleDict``.

.. GENERATED FROM PYTHON SOURCE LINES 12-14

Open the case
-------------

.. GENERATED FROM PYTHON SOURCE LINES 14-37

.. code-block:: Python


    import os
    import subprocess

    import pyOFTools.patch_pybfoam  # noqa: F401
    from pyOFTools import clone_example

    CASE = clone_example("damBreak")
    subprocess.run(
        ["./Allrun"],
        cwd=CASE,
        check=True,
        env={**os.environ},
        capture_output=True,
        text=True,
    )

    from pybFoam import Time, fvMesh, volScalarField

    time = Time(str(CASE.parent), CASE.name)
    mesh = fvMesh(time)
    p_field = volScalarField.read_field(mesh, "p")








.. GENERATED FROM PYTHON SOURCE LINES 38-45

Build the line
--------------
A vertical probe through the middle of the water column.
``create_uniform_set`` takes the field object directly (``p_field``),
which avoids re-reading it — the ``line()`` builder in
:mod:`pyOFTools.builders` would do a second ``read_field`` and
double-register the field in OpenFOAM.

.. GENERATED FROM PYTHON SOURCE LINES 45-57

.. code-block:: Python


    from pyOFTools.sets import create_uniform_set

    dataset = create_uniform_set(
        mesh,
        name="vertical_p",
        start=(0.146, 0.0, 0.0073),
        end=(0.146, 0.584, 0.0073),
        n_points=100,
        field=p_field,
    )








.. GENERATED FROM PYTHON SOURCE LINES 58-60

Plot it
-------

.. GENERATED FROM PYTHON SOURCE LINES 60-75

.. code-block:: Python


    import matplotlib.pyplot as plt
    import numpy as np

    distance = np.asarray(dataset.geometry.distance)
    pressure = np.asarray(dataset.field)

    fig, ax = plt.subplots(figsize=(6, 3.5))
    ax.plot(distance, pressure)
    ax.set_xlabel("distance along line [m]")
    ax.set_ylabel("p [Pa]")
    ax.set_title("Pressure along a vertical line (damBreak, t=0)")
    fig.tight_layout()
    plt.show()




.. image-sg:: /auto_how_to/images/sphx_glr_example_sample_line_001.png
   :alt: Pressure along a vertical line (damBreak, t=0)
   :srcset: /auto_how_to/images/sphx_glr_example_sample_line_001.png
   :class: sphx-glr-single-img





.. GENERATED FROM PYTHON SOURCE LINES 76-81

Aggregate instead of plot
-------------------------
The same ``PointDataSet`` flows into any reducer node. ``Mean`` gives the
arithmetic mean over the sampled points (not a length-weighted mean — use
a ``Sum`` with a manual scaling factor for that).

.. GENERATED FROM PYTHON SOURCE LINES 81-89

.. code-block:: Python


    from pyOFTools.aggregators import Max, Mean
    from pyOFTools.workflow import WorkFlow

    mean_p = (WorkFlow(initial_dataset=dataset) | Mean()).compute()
    max_p = (WorkFlow(initial_dataset=dataset) | Max()).compute()
    print(f"mean p along line = {mean_p.values[0].value:.4g} Pa")
    print(f"max  p along line = {max_p.values[0].value:.4g} Pa")




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

 .. code-block:: none

    mean p along line = 1e+05 Pa
    max  p along line = 1e+05 Pa





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

   **Total running time of the script:** (0 minutes 10.682 seconds)


.. _sphx_glr_download_auto_how_to_example_sample_line.py:

.. only:: html

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

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

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

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

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

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

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


.. only:: html

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

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