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# Hillshading

Demonstrates a few common tricks with shaded plots.

    import numpy as np
    import matplotlib.pyplot as plt
    from matplotlib.colors import LightSource, Normalize

    def display_colorbar():
        """Display a correct numeric colorbar for a shaded plot."""
        y, x = np.mgrid[-4:2:200j, -4:2:200j]
        z = 10 * np.cos(x**2 + y**2)

        cmap = plt.cm.copper
        ls = LightSource(315, 45)
        rgb = ls.shade(z, cmap)

        fig, ax = plt.subplots()
        ax.imshow(rgb, interpolation='bilinear')

        # Use a proxy artist for the colorbar...
        im = ax.imshow(z, cmap=cmap)
        im.remove()
        fig.colorbar(im)

        ax.set_title('Using a colorbar with a shaded plot', size='x-large')

    def avoid_outliers():
        """Use a custom norm to control the displayed z-range of a shaded plot."""
        y, x = np.mgrid[-4:2:200j, -4:2:200j]
        z = 10 * np.cos(x**2 + y**2)

        # Add some outliers...
        z[100, 105] = 2000
        z[120, 110] = -9000

        ls = LightSource(315, 45)
        fig, (ax1, ax2) = plt.subplots(ncols=2, figsize=(8, 4.5))

        rgb = ls.shade(z, plt.cm.copper)
        ax1.imshow(rgb, interpolation='bilinear')
        ax1.set_title('Full range of data')

        rgb = ls.shade(z, plt.cm.copper, vmin=-10, vmax=10)
        ax2.imshow(rgb, interpolation='bilinear')
        ax2.set_title('Manually set range')

        fig.suptitle('Avoiding Outliers in Shaded Plots', size='x-large')

    def shade_other_data():
        """Demonstrates displaying different variables through shade and color."""
        y, x = np.mgrid[-4:2:200j, -4:2:200j]
        z1 = np.sin(x**2)  # Data to hillshade
        z2 = np.cos(x**2 + y**2)  # Data to color

        norm = Normalize(z2.min(), z2.max())
        cmap = plt.cm.RdBu

        ls = LightSource(315, 45)
        rgb = ls.shade_rgb(cmap(norm(z2)), z1)

        fig, ax = plt.subplots()
        ax.imshow(rgb, interpolation='bilinear')
        ax.set_title('Shade by one variable, color by another', size='x-large')

    display_colorbar()
    avoid_outliers()
    shade_other_data()
    plt.show()

Total running time of the script: ( 0 minutes 0.173 seconds)

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