title: Trouble saving matplotlib animation
body: <p>I'm using matplotlib to make an animated heatmap.  I have data in a text file (rs_h) with 3 columns - x, y, z; i'm using scatterplot to make a simple heatmap, and then using the animation package to update the heatmap over time</p>
  
  <pre><code>import pandas as pd
  import matplotlib.pyplot as plt
  import numpy as np
  import matplotlib.animation as animation
  
  data = pd.read_table('rs_h', header=None, sep=r"\s*")
  
  frames = np.array_split(data, 9)
  
  def main():
      numframes = 9
      numpoints = 75
  
      x, y, c = np.random.random((3, numpoints))
  
      fig = plt.figure()
      scat = plt.scatter(x, y, c=c)#, s=100)
  
      ani = animation.FuncAnimation(fig, update_plot, frames=xrange(numframes), 
                                interval = 5)
      #ani.save("movie.avi", codec='avi')
      plt.show()
  
  def update_plot(i):
      frame = frames[i]
      scat = plt.scatter(frame[0], frame[1], c=frame[2])
      return scat,
  
  main()
  </code></pre>
  
  <p>I'm having no trouble getting the animated heatmap; however, i run into an issue when i try to save the animation</p>
  
  <pre><code>/Users/Arjun/anaconda/lib/python2.7/site-packages/matplotlib/animation.py:695: UserWarning: MovieWriter ffmpeg unavailable
    warnings.warn("MovieWriter %s unavailable" % writer)
  Traceback (most recent call last):
    File "heat_ani.py", line 29, in &lt;module&gt;
      main()
    File "heat_ani.py", line 21, in main
      ani.save("movie.avi", codec='avi')
    File "/Users/Arjun/anaconda/lib/python2.7/site-packages/matplotlib/animation.py", line 712, in save
      with writer.saving(self._fig, filename, dpi):
  AttributeError: 'str' object has no attribute 'saving'
  </code></pre>
  
  <p>Anyone know what the issue is and how to get around it?</p>
  
  <p>EDIT:  The issue was that i didn't have ffmpeg installed.  A simple brew install allowed the code to work</p>