title: Transparent markerfacecolor in Matplotlib
body: <p>I would like to plot a bunch of markers (one at a time) that have a semi-transparent face color and an opaque (alpha=1) edge color using Matplotlib.  This seemed straight forward by set each in the plot command using the appropriate rgba values (like it was suggested in <a href="https://stackoverflow.com/a/15936516">this</a> answer), but it's not working
  Sample Code (Updated from original post to better illustrate the issue):</p>
  
  <pre><code>N = 48
  xys = np.random.rand(N,2)
  markers = []
  fig = plt.figure()
  ax = fig.add_subplot(111)
  for i in range(N):
      m = ax.plot(
          xys[i,0], xys[i,1],
          linestyle='None', marker='o', markersize=20,
          markeredgewidth=4, markeredgecolor=(0, 0, 0, 1.0),
          markerfacecolor=(1, 0, 0.2, 0.1),
      )[0]
  ax.grid()
  ax.set_axisbelow(True)
  fig.savefig('scratch_fig.png', dpi=300)
  </code></pre>
  
  <p>That gives me this plot: <a href="https://imgur.com/pcCQlSV" rel="nofollow noreferrer">http://imgur.com/pcCQlSV</a></p>
  
  <p>As you can see the edges are correct, solid black.  But, when you look at the markers that are overlapping each other and the grid you can see that they are not semi-transparent.</p>
  
  <p>I produced this result using Matplotlib 1.2.1 on both Windows 7 and Ubuntu</p>
  
  <p>Does anyone know how to fix this, without creating two sets of overlapping markers?</p>