.. _checkmatplotlibbackendrst:

========================
Check matplotlib backend
========================


.. only:: html

    **Links:** :download:`notebook <check_matplotlib_backend.ipynb>`, :downloadlink:`html <check_matplotlib_backend2html.html>`, :download:`PDF <check_matplotlib_backend.pdf>`, :download:`python <check_matplotlib_backend.py>`, :downloadlink:`slides <check_matplotlib_backend.slides.html>`, :githublink:`GitHub|_doc/notebooks/check_matplotlib_backend.ipynb|*`


The notebook checks matplotlib backend. The backend defines the devices
the module is using to show the results. *backend_inline* should be the
value inside a notebook.

.. code:: ipython3

    %matplotlib inline

.. code:: ipython3

    import matplotlib
    matplotlib.get_backend()




.. parsed-literal::
    'module://ipykernel.pylab.backend_inline'



.. code:: ipython3

    import pyquickhelper

.. code:: ipython3

    import matplotlib
    matplotlib.get_backend()




.. parsed-literal::
    'module://ipykernel.pylab.backend_inline'



The following instruction tends to change matplotlib backend, we just
check it does not happen. If this changes, check you did not import a
module which import matplotlib or did run the following:

::

   from matplotlib.sphinxext.plot_directive import setup as setup_plot
   from matplotlib.sphinxext.only_directives import setup as setup_only

The backend might change in that case to ``'agg'`` and graphs will not
be displayed into the notebook.

.. code:: ipython3

    %load_ext pyquickhelper

.. code:: ipython3

    import matplotlib
    matplotlib.get_backend()




.. parsed-literal::
    'module://ipykernel.pylab.backend_inline'



.. code:: ipython3

    %matplotlib inline

.. code:: ipython3

    import matplotlib
    matplotlib.get_backend()




.. parsed-literal::
    'module://ipykernel.pylab.backend_inline'