Create Parasite Axes with Matplotlib

Introduction

In this lab, you will learn how to create a parasite axes using the mpl_toolkits.axes_grid1.parasite_axes.HostAxes and mpl_toolkits.axes_grid1.parasite_axes.ParasiteAxes modules in Matplotlib. The parasite axes shares the x-scale with a host axes, but shows a different scale in y direction.

VM Tips

After the VM startup is done, click the top left corner to switch to the Notebook tab to access Jupyter Notebook for practice.

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Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL matplotlib(("`Matplotlib`")) -.-> matplotlib/BasicConceptsGroup(["`Basic Concepts`"]) matplotlib(("`Matplotlib`")) -.-> matplotlib/PlottingDataGroup(["`Plotting Data`"]) matplotlib(("`Matplotlib`")) -.-> matplotlib/PlotCustomizationGroup(["`Plot Customization`"]) python(("`Python`")) -.-> python/BasicConceptsGroup(["`Basic Concepts`"]) python(("`Python`")) -.-> python/DataStructuresGroup(["`Data Structures`"]) python(("`Python`")) -.-> python/ModulesandPackagesGroup(["`Modules and Packages`"]) python(("`Python`")) -.-> python/PythonStandardLibraryGroup(["`Python Standard Library`"]) python(("`Python`")) -.-> python/DataScienceandMachineLearningGroup(["`Data Science and Machine Learning`"]) python(("`Python`")) -.-> python/FunctionsGroup(["`Functions`"]) matplotlib/BasicConceptsGroup -.-> matplotlib/importing_matplotlib("`Importing Matplotlib`") matplotlib/BasicConceptsGroup -.-> matplotlib/figures_axes("`Understanding Figures and Axes`") matplotlib/PlottingDataGroup -.-> matplotlib/line_plots("`Line Plots`") matplotlib/PlotCustomizationGroup -.-> matplotlib/legend_config("`Legend Configuration`") python/BasicConceptsGroup -.-> python/variables_data_types("`Variables and Data Types`") python/BasicConceptsGroup -.-> python/booleans("`Booleans`") python/DataStructuresGroup -.-> python/lists("`Lists`") python/DataStructuresGroup -.-> python/tuples("`Tuples`") python/ModulesandPackagesGroup -.-> python/importing_modules("`Importing Modules`") python/ModulesandPackagesGroup -.-> python/using_packages("`Using Packages`") python/PythonStandardLibraryGroup -.-> python/data_collections("`Data Collections`") python/DataScienceandMachineLearningGroup -.-> python/data_visualization("`Data Visualization`") python/FunctionsGroup -.-> python/build_in_functions("`Build-in Functions`") subgraph Lab Skills matplotlib/importing_matplotlib -.-> lab-48682{{"`Demo Parasite Axes`"}} matplotlib/figures_axes -.-> lab-48682{{"`Demo Parasite Axes`"}} matplotlib/line_plots -.-> lab-48682{{"`Demo Parasite Axes`"}} matplotlib/legend_config -.-> lab-48682{{"`Demo Parasite Axes`"}} python/variables_data_types -.-> lab-48682{{"`Demo Parasite Axes`"}} python/booleans -.-> lab-48682{{"`Demo Parasite Axes`"}} python/lists -.-> lab-48682{{"`Demo Parasite Axes`"}} python/tuples -.-> lab-48682{{"`Demo Parasite Axes`"}} python/importing_modules -.-> lab-48682{{"`Demo Parasite Axes`"}} python/using_packages -.-> lab-48682{{"`Demo Parasite Axes`"}} python/data_collections -.-> lab-48682{{"`Demo Parasite Axes`"}} python/data_visualization -.-> lab-48682{{"`Demo Parasite Axes`"}} python/build_in_functions -.-> lab-48682{{"`Demo Parasite Axes`"}} end

Import necessary libraries

First, we need to import the necessary libraries. In this lab, we will be using matplotlib.pyplot for plotting, mpl_toolkits.axes_grid1.parasite_axes.HostAxes and mpl_toolkits.axes_grid1.parasite_axes.ParasiteAxes for creating a parasite axes.

import matplotlib.pyplot as plt
from mpl_toolkits.axisartist.parasite_axes import HostAxes

Create a figure and add host axes

We create a figure using plt.figure() method and add a host axes using fig.add_axes() method. Host axes shares the x-scale with parasite axes.

fig = plt.figure()
host = fig.add_axes([0.15, 0.1, 0.65, 0.8], axes_class=HostAxes)

Create parasite axes

We create two parasite axes using host.get_aux_axes() method. We set viewlim_mode=None to ensure that the parasite axes share the same x-scale with the host axes. We also set sharex=host to ensure that the x-scale is shared.

par1 = host.get_aux_axes(viewlim_mode=None, sharex=host)
par2 = host.get_aux_axes(viewlim_mode=None, sharex=host)

Hide right y-axis of host axes

We hide the right y-axis of the host axes using host.axis["right"].set_visible(False) method.

host.axis["right"].set_visible(False)

Show right y-axis of parasite axes 1

We show the right y-axis of the first parasite axes using par1.axis["right"].set_visible(True) method. We also set par1.axis["right"].major_ticklabels.set_visible(True) and par1.axis["right"].label.set_visible(True) to show the tick labels and label of the right y-axis.

par1.axis["right"].set_visible(True)
par1.axis["right"].major_ticklabels.set_visible(True)
par1.axis["right"].label.set_visible(True)

Add right y-axis to parasite axes 2

We add a right y-axis to the second parasite axes using par2.axis["right2"] = par2.new_fixed_axis(loc="right", offset=(60, 0)) method.

par2.axis["right2"] = par2.new_fixed_axis(loc="right", offset=(60, 0))

Plot data on all axes

We plot data on all axes using plot() method. We also set labels and limits for all axes using set() method.

p1, = host.plot([0, 1, 2], [0, 1, 2], label="Density")
p2, = par1.plot([0, 1, 2], [0, 3, 2], label="Temperature")
p3, = par2.plot([0, 1, 2], [50, 30, 15], label="Velocity")

host.set(xlim=(0, 2), ylim=(0, 2), xlabel="Distance", ylabel="Density")
par1.set(ylim=(0, 4), ylabel="Temperature")
par2.set(ylim=(1, 65), ylabel="Velocity")

Add legend and axis colors

We add a legend to the host axes using host.legend() method. We also set the color of the left y-axis label of the host axes, the right y-axis label of the first parasite axes, and the right y-axis label of the second parasite axes to match their respective lines using host.axis["left"].label.set_color(p1.get_color()), par1.axis["right"].label.set_color(p2.get_color()), and par2.axis["right2"].label.set_color(p3.get_color()) methods.

host.legend()

host.axis["left"].label.set_color(p1.get_color())
par1.axis["right"].label.set_color(p2.get_color())
par2.axis["right2"].label.set_color(p3.get_color())

Display the plot

We display the plot using plt.show() method.

plt.show()

Summary

In this lab, we learned how to create a parasite axes using mpl_toolkits.axes_grid1.parasite_axes.HostAxes and mpl_toolkits.axes_grid1.parasite_axes.ParasiteAxes modules in Matplotlib. We also learned how to plot data on the parasite axes and share the x-scale with the host axes.