.. only:: html .. note:: :class: sphx-glr-download-link-note Click :ref:`here ` to download the full example code .. rst-class:: sphx-glr-example-title .. _sphx_glr_gallery_images_contours_and_fields_contourf_demo.py: ============= Contourf Demo ============= How to use the `.axes.Axes.contourf` method to create filled contour plots. .. code-block:: default import numpy as np import matplotlib.pyplot as plt origin = 'lower' delta = 0.025 x = y = np.arange(-3.0, 3.01, delta) X, Y = np.meshgrid(x, y) Z1 = np.exp(-X**2 - Y**2) Z2 = np.exp(-(X - 1)**2 - (Y - 1)**2) Z = (Z1 - Z2) * 2 nr, nc = Z.shape # put NaNs in one corner: Z[-nr // 6:, -nc // 6:] = np.nan # contourf will convert these to masked Z = np.ma.array(Z) # mask another corner: Z[:nr // 6, :nc // 6] = np.ma.masked # mask a circle in the middle: interior = np.sqrt(X**2 + Y**2) < 0.5 Z[interior] = np.ma.masked # We are using automatic selection of contour levels; # this is usually not such a good idea, because they don't # occur on nice boundaries, but we do it here for purposes # of illustration. fig1, ax2 = plt.subplots(constrained_layout=True) CS = ax2.contourf(X, Y, Z, 10, cmap=plt.cm.bone, origin=origin) # Note that in the following, we explicitly pass in a subset of # the contour levels used for the filled contours. Alternatively, # We could pass in additional levels to provide extra resolution, # or leave out the levels kwarg to use all of the original levels. CS2 = ax2.contour(CS, levels=CS.levels[::2], colors='r', origin=origin) ax2.set_title('Nonsense (3 masked regions)') ax2.set_xlabel('word length anomaly') ax2.set_ylabel('sentence length anomaly') # Make a colorbar for the ContourSet returned by the contourf call. cbar = fig1.colorbar(CS) cbar.ax.set_ylabel('verbosity coefficient') # Add the contour line levels to the colorbar cbar.add_lines(CS2) fig2, ax2 = plt.subplots(constrained_layout=True) # Now make a contour plot with the levels specified, # and with the colormap generated automatically from a list # of colors. levels = [-1.5, -1, -0.5, 0, 0.5, 1] CS3 = ax2.contourf(X, Y, Z, levels, colors=('r', 'g', 'b'), origin=origin, extend='both') # Our data range extends outside the range of levels; make # data below the lowest contour level yellow, and above the # highest level cyan: CS3.cmap.set_under('yellow') CS3.cmap.set_over('cyan') CS4 = ax2.contour(X, Y, Z, levels, colors=('k',), linewidths=(3,), origin=origin) ax2.set_title('Listed colors (3 masked regions)') ax2.clabel(CS4, fmt='%2.1f', colors='w', fontsize=14) # Notice that the colorbar gets all the information it # needs from the ContourSet object, CS3. fig2.colorbar(CS3) # Illustrate all 4 possible "extend" settings: extends = ["neither", "both", "min", "max"] cmap = plt.cm.get_cmap("winter") cmap.set_under("magenta") cmap.set_over("yellow") # Note: contouring simply excludes masked or nan regions, so # instead of using the "bad" colormap value for them, it draws # nothing at all in them. Therefore the following would have # no effect: # cmap.set_bad("red") fig, axs = plt.subplots(2, 2, constrained_layout=True) for ax, extend in zip(axs.ravel(), extends): cs = ax.contourf(X, Y, Z, levels, cmap=cmap, extend=extend, origin=origin) fig.colorbar(cs, ax=ax, shrink=0.9) ax.set_title("extend = %s" % extend) ax.locator_params(nbins=4) plt.show() .. rst-class:: sphx-glr-horizontal * .. image:: /gallery/images_contours_and_fields/images/sphx_glr_contourf_demo_001.png :alt: Nonsense (3 masked regions) :class: sphx-glr-multi-img * .. image:: /gallery/images_contours_and_fields/images/sphx_glr_contourf_demo_002.png :alt: Listed colors (3 masked regions) :class: sphx-glr-multi-img * .. image:: /gallery/images_contours_and_fields/images/sphx_glr_contourf_demo_003.png :alt: extend = neither, extend = both, extend = min, extend = max :class: sphx-glr-multi-img .. rst-class:: sphx-glr-script-out Out: .. code-block:: none /root/matplotlib/examples/images_contours_and_fields/contourf_demo.py:91: MatplotlibDeprecationWarning: You are modifying the state of a globally registered colormap. In future versions, you will not be able to modify a registered colormap in-place. To remove this warning, you can make a copy of the colormap first. cmap = copy.copy(mpl.cm.get_cmap("winter")) cmap.set_under("magenta") /root/matplotlib/examples/images_contours_and_fields/contourf_demo.py:92: MatplotlibDeprecationWarning: You are modifying the state of a globally registered colormap. In future versions, you will not be able to modify a registered colormap in-place. To remove this warning, you can make a copy of the colormap first. cmap = copy.copy(mpl.cm.get_cmap("winter")) cmap.set_over("yellow") ------------ References """""""""" The use of the following functions, methods and classes is shown in this example: .. code-block:: default import matplotlib matplotlib.axes.Axes.contour matplotlib.pyplot.contour matplotlib.axes.Axes.contourf matplotlib.pyplot.contourf matplotlib.axes.Axes.clabel matplotlib.pyplot.clabel matplotlib.figure.Figure.colorbar matplotlib.pyplot.colorbar matplotlib.colors.Colormap matplotlib.colors.Colormap.set_bad matplotlib.colors.Colormap.set_under matplotlib.colors.Colormap.set_over .. rst-class:: sphx-glr-script-out Out: .. code-block:: none .. rst-class:: sphx-glr-timing **Total running time of the script:** ( 0 minutes 1.590 seconds) .. _sphx_glr_download_gallery_images_contours_and_fields_contourf_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: contourf_demo.py ` .. container:: sphx-glr-download sphx-glr-download-jupyter :download:`Download Jupyter notebook: contourf_demo.ipynb ` .. only:: html .. rst-class:: sphx-glr-signature Keywords: matplotlib code example, codex, python plot, pyplot `Gallery generated by Sphinx-Gallery `_