title: Matplotlib animation not working in IPython Notebook (blank plot)
body: <p>I've tried multiple animation sample codes and cannot get any of them working.  Here's a basic one I've tried from the Matplotlib documentation:</p>
  
  <pre><code>"""
  A simple example of an animated plot
  """
  import numpy as np
  import matplotlib.pyplot as plt
  import matplotlib.animation as animation
  
  fig, ax = plt.subplots()
  
  x = np.arange(0, 2*np.pi, 0.01)        # x-array
  line, = ax.plot(x, np.sin(x))
  
  def animate(i):
      line.set_ydata(np.sin(x+i/10.0))  # update the data
      return line,
  
  #Init only required for blitting to give a clean slate.
  def init():
      line.set_ydata(np.ma.array(x, mask=True))
      return line,
  
  ani = animation.FuncAnimation(fig, animate, np.arange(1, 200), init_func=init,
      interval=25, blit=True)
  plt.show()
  </code></pre>
  
  <p>When I execute the above in an IPython Notebook, I just see a blank plot generated.  I've tried running this from multiple servers (including Wakari), on multiple machines, using multiple browsers (Chrome, FF, IE).</p>
  
  <p>I can save the animation to an mp4 file just fine and it looks good when played.</p>
  
  <p>Any help is appreciated!</p>