HillshadingΒΆ

Demonstrates a few common tricks with shaded plots.

  • Using a colorbar with a shaded plot
  • Avoiding Outliers in Shaded Plots, Full range of data, Manually set range
  • Shade by one variable, color by another

Out:

/home/circleci/project/examples/specialty_plots/advanced_hillshading.py:28: MatplotlibDeprecationWarning: Starting from Matplotlib 3.6, colorbar() will steal space from the mappable's axes, rather than from the current axes, to place the colorbar.  To silence this warning, explicitly pass the 'ax' argument to colorbar().
  fig.colorbar(im)

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 2.743 seconds)

Keywords: matplotlib code example, codex, python plot, pyplot Gallery generated by Sphinx-Gallery