title: Matplotlib Half color axis
body: <p>I am using matplotlib to make some plots and I have run into a few difficulties that I need help with. </p>
  
  <p>problem 1) In order to keep a consistent colorscheme I need to only use half of the color axis. There are only positive values, so I want the zero values to be green, the mid values to be yellow and the highest values to be red. The color scheme that most closely matches this is  gist_rainbow_r, but I only want the top half of it.</p>
  
  <p>problem 2) I can't seem to figure out how to get the colorbar on the right hand side of the plot to show up or how to get it to let me label the axes.  </p>
  
  <p>If it helps, I am using the latest version of Anaconda wth the latext version of matplotlib</p>
  
  <pre><code>cmap = plt.get_cmap('gist_rainbow_r')
  edosfig2 = plt.figure(2)
  edossub2 = edosfig.add_subplot(1,1,1)
  edossub2 = plt.contourf(eVec,kints,smallEDOS,cmap=cmap)
  edosfig2.show()
  </code></pre>