matplotlib.pyplot blackmagic to make CTRL-C work again

pyplot_interrupt_handler.py

import sys
import matplotlib.pyplot as plt

try:
    # Put matplotlib.pyplot in interactive mode so that the plots are shown in a background thread.
    plt.ion()
    while(True):
        plt.show()

except KeyboardInterrupt:
    print ""
    sys.exit(0)

I had to change it to

while(True):
    plt.show(block=True)
    break

to make it work. Enabling blocking was necessary to actually show the plots and break to exit the loop in case the user clicks the close button.

doesn't work.

This is what I do to be able to exit the loop:

import matplotlib.pyplot as plt

def handle_close(evt):
    handle_close.stop = True
handle_close.stop = False

plt.ion()
plt.show(block=False)
plt.gcf().canvas.mpl_connect('close_event', handle_close)

while(True):
    if handle_close.stop:
        break
    plt.plot([0,1], [0,1])
    plt.gcf().canvas.flush_events()

plt.show()
plt.ioff()

Still doesn't react to KeyboardInterrupt though.

My use-case involved updating a figure in a for-loop and exit the app once the user requests the termination. In the below example, the user can exit the loop prematurely in three ways:

• Hit "e" or "q" (requires the figure to be the active window)
• Close the figure via the close button
• Interrupt by hitting CTRL+C or CMD+C in the console

The nice thing is that figure/axes can be reused over multiple iterations.

The code below requires python3+. I tested with matplotlib 3.4.1 and python3.8.

import sys
import numpy as np
import matplotlib.pyplot as plt

def test():
    def handle_key(event):
        if event.key in "eEqQ":
            nonlocal show
            show = False
            print("Stop on key press")
            return False

    def handle_close(event):
        nonlocal show
        show = False
        print("Stop on close")

    show = True
    t = np.linspace(0, np.pi, 100)
    fig, ax = plt.subplots()
    fig.canvas.mpl_connect("key_release_event", handle_key)
    fig.canvas.mpl_connect("close_event", handle_close)
    for i in np.linspace(1,10,101):
        if show:
            try:
                ax.clear()
                ax.plot(t, np.sin(i*t))
                # Return values of waitforbuttonpress():
                #   - True if key was pressed
                #   - False if mouse button was pressed
                #   - (None if timeout was reached without event)
                fig.canvas.draw()
                while not fig.waitforbuttonpress() and show:
                    pass
                fig.canvas.flush_events()
            except KeyboardInterrupt:
                print("Stop on interrupt")
                show = False
    plt.close(fig)
    print("Exit normally")

test()

More simple solution: Add at beginning of your program

import signal
signal.signal(signal.SIGINT, signal.SIG_DFL)