Set Alternative Cursor in Matplotlib

Introduction

This lab will guide you on how to set an alternative cursor on a figure canvas using Matplotlib. The alternative cursor can be any of the available cursors in the Matplotlib backend tools.

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Import the necessary libraries

First, we need to import the required libraries. We will be using matplotlib.pyplot and matplotlib.backend_tools.

import matplotlib.pyplot as plt
from matplotlib.backend_tools import Cursors

Create a figure and set alternative cursors

Next, we create a figure and set the alternative cursors for each subplot using a loop. We also add text to each subplot to indicate the cursor being used.

fig, axs = plt.subplots(len(Cursors), figsize=(6, len(Cursors) + 0.5), gridspec_kw={'hspace': 0})
fig.suptitle('Hover over an Axes to see alternate Cursors')

for cursor, ax in zip(Cursors, axs):
    ax.cursor_to_use = cursor
    ax.text(0.5, 0.5, cursor.name,
            horizontalalignment='center', verticalalignment='center')
    ax.set(xticks=[], yticks=[])

Set the cursor on hover

We need to set the cursor to the alternative cursor when the user hovers over a subplot. We achieve this using the motion_notify_event event and the set_cursor() function.

def hover(event):
    if fig.canvas.widgetlock.locked():
        ## Don't do anything if the zoom/pan tools have been enabled.
        return

    fig.canvas.set_cursor(
        event.inaxes.cursor_to_use if event.inaxes else Cursors.POINTER)

fig.canvas.mpl_connect('motion_notify_event', hover)

Display the figure

Finally, we display the figure using the show() function.

plt.show()

Summary

In this lab, we have learned how to set an alternative cursor on a figure canvas using Matplotlib. We created a figure and set the alternative cursors for each subplot, and then set the cursor to the alternative cursor when the user hovers over a subplot. We then displayed the figure.