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

.. only:: html

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

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

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

.. _sphx_glr_examples_contourf.py:


====================
Contour Example
====================

.. GENERATED FROM PYTHON SOURCE LINES 7-105



.. image-sg:: /examples/images/sphx_glr_contourf_001.png
   :alt: contourf
   :srcset: /examples/images/sphx_glr_contourf_001.png
   :class: sphx-glr-single-img


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

 .. code-block:: none

    /home/docs/checkouts/readthedocs.org/user_builds/mpl-skia-pathops/envs/latest/lib/python3.10/site-packages/matplotlib/colors.py:2295: RuntimeWarning: invalid value encountered in divide
      resdat /= (vmax - vmin)






|

.. code-block:: Python


    import numpy as np
    import matplotlib.pyplot as plt
    import mpl_visual_context.patheffects as pe
    from mpl_skia_pathops import SkiaShadow # make_shadow_patheffects

    def make_shadow_patheffects(
            fc_white="w",
            fc_black="0.2",
            alpha=0.5,
            offset=2.5,
            angle=135):

        patheffects = []
        if fc_black is not None:
            patheffects.append(
                SkiaShadow(offset, angle)
                | pe.FillColor(fc_black)
                | pe.GCModify(alpha=alpha)
            )
        if fc_white is not None:
            patheffects.append(
                SkiaShadow(offset, 180+angle)
                | pe.FillColor(fc_white)
                | pe.GCModify(alpha=alpha)
            )

        return patheffects


    from matplotlib.contour import QuadContourSet
    from matplotlib.patches import PathPatch, Polygon
    from matplotlib.path import Path

    # Data
    X, Y = np.meshgrid(np.linspace(-5, 10, 100),
                       np.linspace(-5, 10, 100))
    Z = -np.sqrt(X ** 2 + Y ** 2)

    # Contour
    fig, ax = plt.subplots(1, 1, num=2, clear=True)

    ax.set_aspect(1)
    contours = ax.contourf(X, Y, Z)

    ann = ax.annotate("A", (0, 1), xycoords="axes fraction",
                      xytext=(15, -15), textcoords="offset points", va="top", ha="left", size=50)

    patheffects1 = make_shadow_patheffects(fc_black="k", offset=2, angle=45, alpha=0.8)[:-1]
    patheffects2 = make_shadow_patheffects(fc_black="k", offset=1, angle=45, alpha=1.)[:]
    patheffects = patheffects1 + patheffects2

    ann.set_path_effects(patheffects)


    def add_contour_shadow(ax, contours,
                           fc_white="w",
                           fc_black="0.2",
                           alpha=0.5,
                           offset=2.5,
                           angle=135):

        # we first create patches for the shadow
        zorder = contours.zorder

        patheffects = make_shadow_patheffects(
            fc_white,
            fc_black,
            alpha,
            offset,
            angle
        )


        for level, c in zip(contours.levels, contours.get_facecolors()):

            sub_contours = QuadContourSet(ax, X, Y, Z,
                                          levels=[level, np.inf],
                                          filled=True)
            sub_contours.remove() # the contour is added to the axes by default. We do not want that.

            segs = sub_contours.allsegs[0] # Essentially there is a single level.

            paths = []
            for seg in segs:
                if len(seg):
                    poly = Polygon(seg, fc=c, ec="none")
                    paths.append(poly.get_path())

            if paths: # we combine the paths.
                path = Path.make_compound_path(*paths)
                p = ax.add_patch(PathPatch(path, fc="none", ec="none", zorder=zorder+1))
                p.set_path_effects(patheffects)

    add_contour_shadow(ax, contours, fc_white=None, offset=3, angle=45, alpha=0.6)
    add_contour_shadow(ax, contours, offset=1., angle=45, alpha=0.8)

    plt.show()


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

   **Total running time of the script:** (0 minutes 0.497 seconds)


.. _sphx_glr_download_examples_contourf.py:

.. only:: html

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

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

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

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

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

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

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


.. only:: html

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

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