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# Tricontour Smooth User

Demonstrates high-resolution tricontouring on user-defined triangular grids with matplotlib.tri.UniformTriRefiner

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

    #-----------------------------------------------------------------------------
    # Analytical test function
    #-----------------------------------------------------------------------------
    def function_z(x, y):
        """ A function of 2 variables """
        r1 = np.sqrt((0.5 - x)**2 + (0.5 - y)**2)
        theta1 = np.arctan2(0.5 - x, 0.5 - y)
        r2 = np.sqrt((-x - 0.2)**2 + (-y - 0.2)**2)
        theta2 = np.arctan2(-x - 0.2, -y - 0.2)
        z = -(2 * (np.exp((r1 / 10)**2) - 1) * 30. * np.cos(7. * theta1) +
              (np.exp((r2 / 10)**2) - 1) * 30. * np.cos(11. * theta2) +
              0.7 * (x**2 + y**2))
        return (np.max(z) - z) / (np.max(z) - np.min(z))

    #-----------------------------------------------------------------------------
    # Creating a Triangulation
    #-----------------------------------------------------------------------------
    # First create the x and y coordinates of the points.
    n_angles = 20
    n_radii = 10
    min_radius = 0.15
    radii = np.linspace(min_radius, 0.95, n_radii)

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

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

    # Now create the Triangulation.
    # (Creating a Triangulation without specifying the triangles results in the
    # Delaunay triangulation of the points.)
    triang = tri.Triangulation(x, y)

    # Mask off unwanted triangles.
    xmid = x[triang.triangles].mean(axis=1)
    ymid = y[triang.triangles].mean(axis=1)
    mask = np.where(xmid * xmid + ymid * ymid < min_radius * min_radius, 1, 0)
    triang.set_mask(mask)

    #-----------------------------------------------------------------------------
    # Refine data
    #-----------------------------------------------------------------------------
    refiner = tri.UniformTriRefiner(triang)
    tri_refi, z_test_refi = refiner.refine_field(z, subdiv=3)

    #-----------------------------------------------------------------------------
    # Plot the triangulation and the high-res iso-contours
    #-----------------------------------------------------------------------------
    plt.figure()
    plt.gca().set_aspect('equal')
    plt.triplot(triang, lw=0.5, color='white')

    levels = np.arange(0., 1., 0.025)
    cmap = cm.get_cmap(name='terrain', lut=None)
    plt.tricontourf(tri_refi, z_test_refi, levels=levels, cmap=cmap)
    plt.tricontour(tri_refi, z_test_refi, levels=levels,
                   colors=['0.25', '0.5', '0.5', '0.5', '0.5'],
                   linewidths=[1.0, 0.5, 0.5, 0.5, 0.5])

    plt.title("High-resolution tricontouring")

    plt.show()

Total running time of the script: ( 0 minutes 0.271 seconds)

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