.. only:: html

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

        Click :ref:`here <sphx_glr_download_gallery_images_contours_and_fields_quadmesh_demo.py>`     to download the full example code
    .. rst-class:: sphx-glr-example-title

    .. _sphx_glr_gallery_images_contours_and_fields_quadmesh_demo.py:


=============
QuadMesh Demo
=============

`~.axes.Axes.pcolormesh` uses a `~matplotlib.collections.QuadMesh`,
a faster generalization of `~.axes.Axes.pcolor`, but with some restrictions.

This demo illustrates a bug in quadmesh with masked data.


.. code-block:: default


    import copy

    from matplotlib import cm, pyplot as plt
    import numpy as np

    n = 12
    x = np.linspace(-1.5, 1.5, n)
    y = np.linspace(-1.5, 1.5, n * 2)
    X, Y = np.meshgrid(x, y)
    Qx = np.cos(Y) - np.cos(X)
    Qz = np.sin(Y) + np.sin(X)
    Z = np.sqrt(X**2 + Y**2) / 5
    Z = (Z - Z.min()) / (Z.max() - Z.min())

    # The color array can include masked values.
    Zm = np.ma.masked_where(np.abs(Qz) < 0.5 * np.max(Qz), Z)

    fig, axs = plt.subplots(nrows=1, ncols=3)
    axs[0].pcolormesh(Qx, Qz, Z, shading='gouraud')
    axs[0].set_title('Without masked values')

    # You can control the color of the masked region. We copy the default colormap
    # before modifying it.
    cmap = copy.copy(cm.get_cmap(plt.rcParams['image.cmap']))
    cmap.set_bad('y', 1.0)
    axs[1].pcolormesh(Qx, Qz, Zm, shading='gouraud', cmap=cmap)
    axs[1].set_title('With masked values')

    # Or use the default, which is transparent.
    axs[2].pcolormesh(Qx, Qz, Zm, shading='gouraud')
    axs[2].set_title('With masked values')

    fig.tight_layout()
    plt.show()




.. image:: /gallery/images_contours_and_fields/images/sphx_glr_quadmesh_demo_001.png
    :alt: Without masked values, With masked values, With masked values
    :class: sphx-glr-single-img





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

References
""""""""""

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


.. code-block:: default


    import matplotlib
    matplotlib.axes.Axes.pcolormesh
    matplotlib.pyplot.pcolormesh




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

 Out:

 .. code-block:: none


    <function pcolormesh at 0x7f79f26d2820>




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

   **Total running time of the script:** ( 0 minutes  1.245 seconds)


.. _sphx_glr_download_gallery_images_contours_and_fields_quadmesh_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: quadmesh_demo.py <quadmesh_demo.py>`



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

     :download:`Download Jupyter notebook: quadmesh_demo.ipynb <quadmesh_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>`_