Embedding Matplotlib Animations in Jupyter Notebooks

In his blog post Embedding Matplotlib Animations in IPython Notebooks, Jake VanderPlas presents a slick hack for embedding Matplotlib Animations in IPython Notebooks, which involves writing it as a video to a tempfile, and then re-encoding it in Base64 as a HTML5 Video.

Unfortunately (or rather fortunately), this hack has been largely rendered obsolete by the heavy development efforts dedicated to both Matplotlib and IPython Notebook (since renamed to Jupyter Notebook) in recent years. In particular, Matplotlib 1.5.1 now supports inline display of animations in the notebook with the to_html5_video method, which converts the animation to an h264 encoded video and embeddeds it directly in the notebook.

In this notebook, we reproduce Jake VanderPlas' blog post with this new feature.

In [1]:
%matplotlib inline
In [2]:
import numpy as np
import matplotlib.pyplot as plt

from matplotlib import animation, rc
from IPython.display import HTML
In [3]:
# First set up the figure, the axis, and the plot element we want to animate
fig, ax = plt.subplots()

ax.set_xlim(( 0, 2))
ax.set_ylim((-2, 2))

line, = ax.plot([], [], lw=2)
In [4]:
# initialization function: plot the background of each frame
def init():
    line.set_data([], [])
    return (line,)
In [5]:
# animation function. This is called sequentially
def animate(i):
    x = np.linspace(0, 2, 1000)
    y = np.sin(2 * np.pi * (x - 0.01 * i))
    line.set_data(x, y)
    return (line,)
In [6]:
# call the animator. blit=True means only re-draw the parts that have changed.
anim = animation.FuncAnimation(fig, animate, init_func=init,
                               frames=100, interval=20, blit=True)
In [7]:
HTML(anim.to_html5_video())
Out[7]:

Note that Animation instances now have a _repr_html_ method. However, it returns None by default.

In [8]:
anim._repr_html_() is None
Out[8]:
True

This means we won't get any sort of animation from the inline display.

In [9]:
anim
Out[9]:
<matplotlib.animation.FuncAnimation at 0x109421828>

The method used to display is controlled by the animation.html rc parameter, which currently supports values of none and html5. none is the default, performing no display. We simply need to set it to html5:

In [10]:
# equivalent to rcParams['animation.html'] = 'html5'
rc('animation', html='html5')
In [11]:
anim
Out[11]:

And that's all there is to it!

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