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

.. only:: html

    .. meta::
        :keywords: codex

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

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

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

.. _sphx_glr_gallery_images_contours_and_fields_contourf_log.py:


============================
Contourf and log color scale
============================

Demonstrate use of a log color scale in contourf

.. GENERATED FROM PYTHON SOURCE LINES 8-52

.. code-block:: Python


    import matplotlib.pyplot as plt
    import numpy as np
    from numpy import ma

    from matplotlib import cm, ticker

    N = 100
    x = np.linspace(-3.0, 3.0, N)
    y = np.linspace(-2.0, 2.0, N)

    X, Y = np.meshgrid(x, y)

    # A low hump with a spike coming out.
    # Needs to have z/colour axis on a log scale, so we see both hump and spike.
    # A linear scale only shows the spike.
    Z1 = np.exp(-X**2 - Y**2)
    Z2 = np.exp(-(X * 10)**2 - (Y * 10)**2)
    z = Z1 + 50 * Z2

    # Put in some negative values (lower left corner) to cause trouble with logs:
    z[:5, :5] = -1

    # The following is not strictly essential, but it will eliminate
    # a warning.  Comment it out to see the warning.
    z = ma.masked_where(z <= 0, z)


    # Automatic selection of levels works; setting the
    # log locator tells contourf to use a log scale:
    fig, ax = plt.subplots()
    cs = ax.contourf(X, Y, z, locator=ticker.LogLocator(), cmap=cm.PuBu_r)

    # Alternatively, you can manually set the levels
    # and the norm:
    # lev_exp = np.arange(np.floor(np.log10(z.min())-1),
    #                    np.ceil(np.log10(z.max())+1))
    # levs = np.power(10, lev_exp)
    # cs = ax.contourf(X, Y, z, levs, norm=colors.LogNorm())

    cbar = fig.colorbar(cs)

    plt.show()




.. image-sg:: /gallery/images_contours_and_fields/images/sphx_glr_contourf_log_001.png
   :alt: contourf log
   :srcset: /gallery/images_contours_and_fields/images/sphx_glr_contourf_log_001.png, /gallery/images_contours_and_fields/images/sphx_glr_contourf_log_001_2_00x.png 2.00x
   :class: sphx-glr-single-img





.. GENERATED FROM PYTHON SOURCE LINES 53-62

.. admonition:: References

   The use of the following functions, methods, classes and modules is shown
   in this example:

   - `matplotlib.axes.Axes.contourf` / `matplotlib.pyplot.contourf`
   - `matplotlib.figure.Figure.colorbar` / `matplotlib.pyplot.colorbar`
   - `matplotlib.axes.Axes.legend` / `matplotlib.pyplot.legend`
   - `matplotlib.ticker.LogLocator`


.. _sphx_glr_download_gallery_images_contours_and_fields_contourf_log.py:

.. only:: html

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

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

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

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

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


.. only:: html

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

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