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

.. only:: html

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

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

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

.. _sphx_glr_examples_gallery_advanced_pdes_post_step_hook_class.py:


Post-step hook function in a custom class
=========================================

The hook function created by :meth:`~pde.pdes.PDEBase.make_post_step_hook` is called
after each time step. The function can modify the state, keep track of additional
information, and abort the simulation.

.. GENERATED FROM PYTHON SOURCE LINES 9-41



.. image-sg:: /examples_gallery/advanced_pdes/images/sphx_glr_post_step_hook_class_001.png
   :alt: Total correction=651.6439721484724
   :srcset: /examples_gallery/advanced_pdes/images/sphx_glr_post_step_hook_class_001.png
   :class: sphx-glr-single-img


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

 .. code-block:: none


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.. code-block:: Python


    from pde import PDEBase, ScalarField, UnitGrid


    class CustomPDE(PDEBase):
        def make_post_step_hook(self, state):
            """Create a hook function that is called after every time step."""

            def post_step_hook(state_data, t, post_step_data):
                """Limit state 1 and abort when standard deviation exceeds 1."""
                i = state_data > 1  # get violating entries
                overshoot = (state_data[i] - 1).sum()  # get total correction
                state_data[i] = 1  # limit data entries
                post_step_data += overshoot  # accumulate total correction
                if post_step_data > 400:
                    # Abort simulation when correction exceeds 400
                    # Note that the `post_step_data` of the previous step will be returned.
                    raise StopIteration

            return post_step_hook, 0.0  # hook function and initial value for data

        def evolution_rate(self, state, t=0):
            """Evaluate the right hand side of the evolution equation."""
            return state.__class__(state.grid, data=1)  # constant growth


    grid = UnitGrid([64, 64])  # generate grid
    state = ScalarField.random_uniform(grid, 0.0, 0.5)  # generate initial condition

    eq = CustomPDE()
    result = eq.solve(state, dt=0.1, t_range=1e4)
    result.plot(title=f"Total correction={eq.diagnostics['solver']['post_step_data']}")


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

   **Total running time of the script:** (0 minutes 0.058 seconds)


.. _sphx_glr_download_examples_gallery_advanced_pdes_post_step_hook_class.py:

.. only:: html

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

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

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

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

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

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

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