
.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/images_contours_and_fields/tripcolor_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_tripcolor_demo.py>`
        to download the full example code

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

.. _sphx_glr_gallery_images_contours_and_fields_tripcolor_demo.py:


==============
Tripcolor Demo
==============

Pseudocolor plots of unstructured triangular grids.

.. GENERATED FROM PYTHON SOURCE LINES 8-12

.. code-block:: default

    import matplotlib.pyplot as plt
    import matplotlib.tri as tri
    import numpy as np








.. GENERATED FROM PYTHON SOURCE LINES 13-15

Creating a Triangulation without specifying the triangles results in the
Delaunay triangulation of the points.

.. GENERATED FROM PYTHON SOURCE LINES 15-38

.. code-block:: default


    # First create the x and y coordinates of the points.
    n_angles = 36
    n_radii = 8
    min_radius = 0.25
    radii = np.linspace(min_radius, 0.95, n_radii)

    angles = np.linspace(0, 2 * np.pi, n_angles, endpoint=False)
    angles = np.repeat(angles[..., np.newaxis], n_radii, axis=1)
    angles[:, 1::2] += np.pi / n_angles

    x = (radii * np.cos(angles)).flatten()
    y = (radii * np.sin(angles)).flatten()
    z = (np.cos(radii) * np.cos(3 * angles)).flatten()

    # Create the Triangulation; no triangles so Delaunay triangulation created.
    triang = tri.Triangulation(x, y)

    # Mask off unwanted triangles.
    triang.set_mask(np.hypot(x[triang.triangles].mean(axis=1),
                             y[triang.triangles].mean(axis=1))
                    < min_radius)








.. GENERATED FROM PYTHON SOURCE LINES 39-40

tripcolor plot.

.. GENERATED FROM PYTHON SOURCE LINES 40-47

.. code-block:: default


    fig1, ax1 = plt.subplots()
    ax1.set_aspect('equal')
    tpc = ax1.tripcolor(triang, z, shading='flat')
    fig1.colorbar(tpc)
    ax1.set_title('tripcolor of Delaunay triangulation, flat shading')




.. image:: /gallery/images_contours_and_fields/images/sphx_glr_tripcolor_demo_001.png
    :alt: tripcolor of Delaunay triangulation, flat shading
    :class: sphx-glr-single-img


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

 Out:

 .. code-block:: none


    Text(0.5, 1.0, 'tripcolor of Delaunay triangulation, flat shading')



.. GENERATED FROM PYTHON SOURCE LINES 48-49

Illustrate Gouraud shading.

.. GENERATED FROM PYTHON SOURCE LINES 49-57

.. code-block:: default


    fig2, ax2 = plt.subplots()
    ax2.set_aspect('equal')
    tpc = ax2.tripcolor(triang, z, shading='gouraud')
    fig2.colorbar(tpc)
    ax2.set_title('tripcolor of Delaunay triangulation, gouraud shading')





.. image:: /gallery/images_contours_and_fields/images/sphx_glr_tripcolor_demo_002.png
    :alt: tripcolor of Delaunay triangulation, gouraud shading
    :class: sphx-glr-single-img


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

 Out:

 .. code-block:: none


    Text(0.5, 1.0, 'tripcolor of Delaunay triangulation, gouraud shading')



.. GENERATED FROM PYTHON SOURCE LINES 58-62

You can specify your own triangulation rather than perform a Delaunay
triangulation of the points, where each triangle is given by the indices of
the three points that make up the triangle, ordered in either a clockwise or
anticlockwise manner.

.. GENERATED FROM PYTHON SOURCE LINES 62-110

.. code-block:: default


    xy = np.asarray([
        [-0.101, 0.872], [-0.080, 0.883], [-0.069, 0.888], [-0.054, 0.890],
        [-0.045, 0.897], [-0.057, 0.895], [-0.073, 0.900], [-0.087, 0.898],
        [-0.090, 0.904], [-0.069, 0.907], [-0.069, 0.921], [-0.080, 0.919],
        [-0.073, 0.928], [-0.052, 0.930], [-0.048, 0.942], [-0.062, 0.949],
        [-0.054, 0.958], [-0.069, 0.954], [-0.087, 0.952], [-0.087, 0.959],
        [-0.080, 0.966], [-0.085, 0.973], [-0.087, 0.965], [-0.097, 0.965],
        [-0.097, 0.975], [-0.092, 0.984], [-0.101, 0.980], [-0.108, 0.980],
        [-0.104, 0.987], [-0.102, 0.993], [-0.115, 1.001], [-0.099, 0.996],
        [-0.101, 1.007], [-0.090, 1.010], [-0.087, 1.021], [-0.069, 1.021],
        [-0.052, 1.022], [-0.052, 1.017], [-0.069, 1.010], [-0.064, 1.005],
        [-0.048, 1.005], [-0.031, 1.005], [-0.031, 0.996], [-0.040, 0.987],
        [-0.045, 0.980], [-0.052, 0.975], [-0.040, 0.973], [-0.026, 0.968],
        [-0.020, 0.954], [-0.006, 0.947], [ 0.003, 0.935], [ 0.006, 0.926],
        [ 0.005, 0.921], [ 0.022, 0.923], [ 0.033, 0.912], [ 0.029, 0.905],
        [ 0.017, 0.900], [ 0.012, 0.895], [ 0.027, 0.893], [ 0.019, 0.886],
        [ 0.001, 0.883], [-0.012, 0.884], [-0.029, 0.883], [-0.038, 0.879],
        [-0.057, 0.881], [-0.062, 0.876], [-0.078, 0.876], [-0.087, 0.872],
        [-0.030, 0.907], [-0.007, 0.905], [-0.057, 0.916], [-0.025, 0.933],
        [-0.077, 0.990], [-0.059, 0.993]])
    x, y = np.rad2deg(xy).T

    triangles = np.asarray([
        [67, 66,  1], [65,  2, 66], [ 1, 66,  2], [64,  2, 65], [63,  3, 64],
        [60, 59, 57], [ 2, 64,  3], [ 3, 63,  4], [ 0, 67,  1], [62,  4, 63],
        [57, 59, 56], [59, 58, 56], [61, 60, 69], [57, 69, 60], [ 4, 62, 68],
        [ 6,  5,  9], [61, 68, 62], [69, 68, 61], [ 9,  5, 70], [ 6,  8,  7],
        [ 4, 70,  5], [ 8,  6,  9], [56, 69, 57], [69, 56, 52], [70, 10,  9],
        [54, 53, 55], [56, 55, 53], [68, 70,  4], [52, 56, 53], [11, 10, 12],
        [69, 71, 68], [68, 13, 70], [10, 70, 13], [51, 50, 52], [13, 68, 71],
        [52, 71, 69], [12, 10, 13], [71, 52, 50], [71, 14, 13], [50, 49, 71],
        [49, 48, 71], [14, 16, 15], [14, 71, 48], [17, 19, 18], [17, 20, 19],
        [48, 16, 14], [48, 47, 16], [47, 46, 16], [16, 46, 45], [23, 22, 24],
        [21, 24, 22], [17, 16, 45], [20, 17, 45], [21, 25, 24], [27, 26, 28],
        [20, 72, 21], [25, 21, 72], [45, 72, 20], [25, 28, 26], [44, 73, 45],
        [72, 45, 73], [28, 25, 29], [29, 25, 31], [43, 73, 44], [73, 43, 40],
        [72, 73, 39], [72, 31, 25], [42, 40, 43], [31, 30, 29], [39, 73, 40],
        [42, 41, 40], [72, 33, 31], [32, 31, 33], [39, 38, 72], [33, 72, 38],
        [33, 38, 34], [37, 35, 38], [34, 38, 35], [35, 37, 36]])

    xmid = x[triangles].mean(axis=1)
    ymid = y[triangles].mean(axis=1)
    x0 = -5
    y0 = 52
    zfaces = np.exp(-0.01 * ((xmid - x0) * (xmid - x0) +
                             (ymid - y0) * (ymid - y0)))








.. GENERATED FROM PYTHON SOURCE LINES 111-117

Rather than create a Triangulation object, can simply pass x, y and triangles
arrays to tripcolor directly.  It would be better to use a Triangulation
object if the same triangulation was to be used more than once to save
duplicated calculations.
Can specify one color value per face rather than one per point by using the
facecolors kwarg.

.. GENERATED FROM PYTHON SOURCE LINES 117-128

.. code-block:: default


    fig3, ax3 = plt.subplots()
    ax3.set_aspect('equal')
    tpc = ax3.tripcolor(x, y, triangles, facecolors=zfaces, edgecolors='k')
    fig3.colorbar(tpc)
    ax3.set_title('tripcolor of user-specified triangulation')
    ax3.set_xlabel('Longitude (degrees)')
    ax3.set_ylabel('Latitude (degrees)')

    plt.show()




.. image:: /gallery/images_contours_and_fields/images/sphx_glr_tripcolor_demo_003.png
    :alt: tripcolor of user-specified triangulation
    :class: sphx-glr-single-img





.. GENERATED FROM PYTHON SOURCE LINES 129-136

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

References
""""""""""

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

.. GENERATED FROM PYTHON SOURCE LINES 137-143

.. code-block:: default


    import matplotlib
    matplotlib.axes.Axes.tripcolor
    matplotlib.pyplot.tripcolor
    matplotlib.tri
    matplotlib.tri.Triangulation








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

   **Total running time of the script:** ( 0 minutes  3.051 seconds)


.. _sphx_glr_download_gallery_images_contours_and_fields_tripcolor_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: tripcolor_demo.py <tripcolor_demo.py>`



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

     :download:`Download Jupyter notebook: tripcolor_demo.ipynb <tripcolor_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>`_
