title: Updating marker style in scatter plot with matplotlib
body: <p>I am working on an interactive plotting application which requires users to select data points from a matplotlib scatter plot. For clarity, I would like to be able to alter the colour and shape of a plotted point when it is clicked on (or selected by any means).</p>
  
  <p>As the <code>matplotlib.collections.PathCollection</code> class has a <code>set_facecolors</code> method, altering the color of the points is relatively simple. However, I cannot see a similar way to update the marker shape. </p>
  
  <p>Is there a way to do this?</p>
  
  <p>A barebones illustration of the problem:</p>
  
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt
  
  x = np.random.normal(0,1.0,100)
  y = np.random.normal(0,1.0,100)
  
  scatter_plot = plt.scatter(x, y, facecolor="b", marker="o")
  
  #update the colour 
  new_facecolors = ["r","g"]*50
  scatter_plot.set_facecolors(new_facecolors)
  
  #update the marker? 
  #new_marker = ["o","s"]*50
  #scatter_plot.???(new_marker)  #&lt;--how do I access the marker shapes?  
  
  plt.show()
  </code></pre>
  
  <p>Any ideas?</p>