title: Setting matplotlib colorbar range
body: <p>I would like to set the matplotlib colorbar range.  Here's what I have so far:</p>
  
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt
  x = np.arange(20)
  y = np.arange(20)
  data = x[:-1,None]+y[None,:-1]
  
  fig = plt.gcf()
  ax = fig.add_subplot(111)
  
  X,Y = np.meshgrid(x,y)
  quadmesh = ax.pcolormesh(X,Y,data)
  plt.colorbar(quadmesh)
  
  #RuntimeError: You must first define an image, eg with imshow
  #plt.clim(vmin=0,vmax=15)  
  
  #AttributeError: 'AxesSubplot' object has no attribute 'clim'
  #ax.clim(vmin=0,vmax=15) 
  
  #AttributeError: 'AxesSubplot' object has no attribute 'set_clim'
  #ax.set_clim(vmin=0,vmax=15) 
  
  plt.show()
  </code></pre>
  
  <p>How do I set the colorbar limits here?</p>