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)

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)