
.. 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_demo.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

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

        Click :ref:`here <sphx_glr_download_gallery_images_contours_and_fields_contourf_demo.py>`
        to download the full example code

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

.. _sphx_glr_gallery_images_contours_and_fields_contourf_demo.py:


=============
Contourf Demo
=============

How to use the `.axes.Axes.contourf` method to create filled contour plots.

.. GENERATED FROM PYTHON SOURCE LINES 8-109

.. code-block:: default


    import numpy as np
    import matplotlib.pyplot as plt

    origin = 'lower'

    delta = 0.025

    x = y = np.arange(-3.0, 3.01, delta)
    X, Y = np.meshgrid(x, y)
    Z1 = np.exp(-X**2 - Y**2)
    Z2 = np.exp(-(X - 1)**2 - (Y - 1)**2)
    Z = (Z1 - Z2) * 2

    nr, nc = Z.shape

    # put NaNs in one corner:
    Z[-nr // 6:, -nc // 6:] = np.nan
    # contourf will convert these to masked


    Z = np.ma.array(Z)
    # mask another corner:
    Z[:nr // 6, :nc // 6] = np.ma.masked

    # mask a circle in the middle:
    interior = np.sqrt(X**2 + Y**2) < 0.5
    Z[interior] = np.ma.masked

    # We are using automatic selection of contour levels;
    # this is usually not such a good idea, because they don't
    # occur on nice boundaries, but we do it here for purposes
    # of illustration.

    fig1, ax2 = plt.subplots(constrained_layout=True)
    CS = ax2.contourf(X, Y, Z, 10, cmap=plt.cm.bone, origin=origin)

    # Note that in the following, we explicitly pass in a subset of
    # the contour levels used for the filled contours.  Alternatively,
    # We could pass in additional levels to provide extra resolution,
    # or leave out the levels kwarg to use all of the original levels.

    CS2 = ax2.contour(CS, levels=CS.levels[::2], colors='r', origin=origin)

    ax2.set_title('Nonsense (3 masked regions)')
    ax2.set_xlabel('word length anomaly')
    ax2.set_ylabel('sentence length anomaly')

    # Make a colorbar for the ContourSet returned by the contourf call.
    cbar = fig1.colorbar(CS)
    cbar.ax.set_ylabel('verbosity coefficient')
    # Add the contour line levels to the colorbar
    cbar.add_lines(CS2)

    fig2, ax2 = plt.subplots(constrained_layout=True)
    # Now make a contour plot with the levels specified,
    # and with the colormap generated automatically from a list
    # of colors.
    levels = [-1.5, -1, -0.5, 0, 0.5, 1]
    CS3 = ax2.contourf(X, Y, Z, levels,
                       colors=('r', 'g', 'b'),
                       origin=origin,
                       extend='both')
    # Our data range extends outside the range of levels; make
    # data below the lowest contour level yellow, and above the
    # highest level cyan:
    CS3.cmap.set_under('yellow')
    CS3.cmap.set_over('cyan')

    CS4 = ax2.contour(X, Y, Z, levels,
                      colors=('k',),
                      linewidths=(3,),
                      origin=origin)
    ax2.set_title('Listed colors (3 masked regions)')
    ax2.clabel(CS4, fmt='%2.1f', colors='w', fontsize=14)

    # Notice that the colorbar gets all the information it
    # needs from the ContourSet object, CS3.
    fig2.colorbar(CS3)

    # Illustrate all 4 possible "extend" settings:
    extends = ["neither", "both", "min", "max"]
    cmap = plt.cm.get_cmap("winter")
    cmap.set_under("magenta")
    cmap.set_over("yellow")
    # Note: contouring simply excludes masked or nan regions, so
    # instead of using the "bad" colormap value for them, it draws
    # nothing at all in them.  Therefore the following would have
    # no effect:
    # cmap.set_bad("red")

    fig, axs = plt.subplots(2, 2, constrained_layout=True)

    for ax, extend in zip(axs.ravel(), extends):
        cs = ax.contourf(X, Y, Z, levels, cmap=cmap, extend=extend, origin=origin)
        fig.colorbar(cs, ax=ax, shrink=0.9)
        ax.set_title("extend = %s" % extend)
        ax.locator_params(nbins=4)

    plt.show()




.. rst-class:: sphx-glr-horizontal


    *

      .. image:: /gallery/images_contours_and_fields/images/sphx_glr_contourf_demo_001.png
          :alt: Nonsense (3 masked regions)
          :class: sphx-glr-multi-img

    *

      .. image:: /gallery/images_contours_and_fields/images/sphx_glr_contourf_demo_002.png
          :alt: Listed colors (3 masked regions)
          :class: sphx-glr-multi-img

    *

      .. image:: /gallery/images_contours_and_fields/images/sphx_glr_contourf_demo_003.png
          :alt: extend = neither, extend = both, extend = min, extend = max
          :class: sphx-glr-multi-img


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

 Out:

 .. code-block:: none

    /build/matplotlib-eAPYn3/matplotlib-3.3.4/examples/images_contours_and_fields/contourf_demo.py:91: MatplotlibDeprecationWarning: You are modifying the state of a globally registered colormap. In future versions, you will not be able to modify a registered colormap in-place. To remove this warning, you can make a copy of the colormap first. cmap = copy.copy(mpl.cm.get_cmap("winter"))
      cmap.set_under("magenta")
    /build/matplotlib-eAPYn3/matplotlib-3.3.4/examples/images_contours_and_fields/contourf_demo.py:92: MatplotlibDeprecationWarning: You are modifying the state of a globally registered colormap. In future versions, you will not be able to modify a registered colormap in-place. To remove this warning, you can make a copy of the colormap first. cmap = copy.copy(mpl.cm.get_cmap("winter"))
      cmap.set_over("yellow")




.. GENERATED FROM PYTHON SOURCE LINES 110-117

------------

References
""""""""""

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

.. GENERATED FROM PYTHON SOURCE LINES 118-132

.. code-block:: default


    import matplotlib
    matplotlib.axes.Axes.contour
    matplotlib.pyplot.contour
    matplotlib.axes.Axes.contourf
    matplotlib.pyplot.contourf
    matplotlib.axes.Axes.clabel
    matplotlib.pyplot.clabel
    matplotlib.figure.Figure.colorbar
    matplotlib.pyplot.colorbar
    matplotlib.colors.Colormap
    matplotlib.colors.Colormap.set_bad
    matplotlib.colors.Colormap.set_under
    matplotlib.colors.Colormap.set_over




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

 Out:

 .. code-block:: none


    <function Colormap.set_over at 0x7f73c13efa60>




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

   **Total running time of the script:** ( 0 minutes  3.031 seconds)


.. _sphx_glr_download_gallery_images_contours_and_fields_contourf_demo.py:


.. only :: html

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



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

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



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

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


.. only:: html

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

    Keywords: matplotlib code example, codex, python plot, pyplot
    `Gallery generated by Sphinx-Gallery
    <https://sphinx-gallery.readthedocs.io>`_
