stop / start / pause in python matplotlib animation

Question

I'm using FuncAnimation in matplotlib's animation module for some basic animation. This function perpetually loops through the animation. Is there a way by which I can pause and restart the animation by, say, mouse clicks?

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Answer 1

Here is a FuncAnimation example which I modified to pause on mouse clicks. Since the animation is driven by a generator function, simData , when the global variable pause is True, yielding the same data makes the animation appear paused.

The value of paused is toggled by setting up an event callback:

def onClick(event):
    global pause
    pause ^= True
fig.canvas.mpl_connect('button_press_event', onClick)

---

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

pause = False
def simData():
    t_max = 10.0
    dt = 0.05
    x = 0.0
    t = 0.0
    while t < t_max:
        if not pause:
            x = np.sin(np.pi*t)
            t = t + dt
        yield x, t

def onClick(event):
    global pause
    pause ^= True

def simPoints(simData):
    x, t = simData[0], simData[1]
    time_text.set_text(time_template%(t))
    line.set_data(t, x)
    return line, time_text

fig = plt.figure()
ax = fig.add_subplot(111)
line, = ax.plot([], [], 'bo', ms=10)
ax.set_ylim(-1, 1)
ax.set_xlim(0, 10)

time_template = 'Time = %.1f s'
time_text = ax.text(0.05, 0.9, '', transform=ax.transAxes)
fig.canvas.mpl_connect('button_press_event', onClick)
ani = animation.FuncAnimation(fig, simPoints, simData, blit=False, interval=10,
    repeat=True)
fig.show()

Answer 2

This works...

anim = animation.FuncAnimation(fig, animfunc[,..other args])

#pause
anim.event_source.stop()

#unpause
anim.event_source.start()

Answer 3

Combining both the answers from @fred and @unutbu here, we can add an onClick function after creating the animation:

import matplotlib.pyplot as plt
import matplotlib.animation as animation

fig = plt.figure()

def run_animation():
    anim_running = True

    def onClick(event):
        nonlocal anim_running
        if anim_running:
            anim.event_source.stop()
            anim_running = False
        else:
            anim.event_source.start()
            anim_running = True

    def animFunc( ...args... ):
        # Animation update function here

    fig.canvas.mpl_connect('button_press_event', onClick)

    anim = animation.FuncAnimation(fig, animFunc[,...other args])

run_animation()

Now we can simply stop or start the animation with clicks.

Answer 4

I landed on this page trying to implement the same functionality, pausing matplotlibs animation. The other answers are great, but in addition I wanted to be able to manually loop through the frames using the arrow keys. For anyone looking for the same functionality, here's my implementation:

import matplotlib.pyplot as plt
import matplotlib.animation as ani

fig, ax = plt.subplots()
txt = fig.text(0.5,0.5,'0')

def update_time():
    t = 0
    t_max = 10
    while t<t_max:
        t += anim.direction
        yield t

def update_plot(t):
    txt.set_text('%s'%t)
    return txt

def on_press(event):
    if event.key.isspace():
        if anim.running:
            anim.event_source.stop()
        else:
            anim.event_source.start()
        anim.running ^= True
    elif event.key == 'left':
        anim.direction = -1
    elif event.key == 'right':
        anim.direction = +1

    # Manually update the plot
    if event.key in ['left','right']:
        t = anim.frame_seq.next()
        update_plot(t)
        plt.draw()

fig.canvas.mpl_connect('key_press_event', on_press)
anim = ani.FuncAnimation(fig, update_plot, frames=update_time,
                         interval=1000, repeat=True)
anim.running = True
anim.direction = +1
plt.show()

Some notes:

• To be able to modify the values of running and direction , I assigned them to anim . It avoids using nonlocal (not avaible in Python2.7) or global (not desirable since I'm running this code within another function). Not sure whether this is good practice, but I found it quite elegant.
• For the manual update, I'm accessing anim 's generator object that FuncAnimation uses to update the plot. This ensures that when I resume the animation, it starts from the active frame rather than from where it was originally paused.

Answer 5

Since there are quite a few comments on different answers asking for documented feature, I dug deeper based on fred's answer . It seems to work, but since matplotlib 3.4.0 there are new functions to pause and resume plotting: pause() and resume() . They call event_source.stop() and start() internally, but they also pause animation altogether, which may reduce the hardware strain.

They can be called on any matplotlib.animation.Animation object, including FuncAnimation subclass.