title: Matplotlib colorbar for PatchCollection overrides colors
body: <p>I am plotting patches according to values set in the variable values. </p>
  
  <pre><code>pc = PatchCollection(patches, match_original=True)  
  
  norm = Normalize()
  cmap = plt.get_cmap('Blues')
  pc.set_facecolor(cmap(norm(values)))
  ax.add_collection(pc)
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/hqdn9.png" alt="enter image description here"></p>
  
  <p>Now i also want an additional colorbar. If i interject (e.g. before set_facecolor) </p>
  
  <pre><code>pc.set_array(values) # values
  plt.colorbar(pc)
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/rJpBH.png" alt="enter image description here"></p>
  
  <p>it works, but now all colors have turned to a greyscale. The following <code>set_facecolor</code> does not change anything. Even when i add a <code>cmap=</code> command in the <code>plt.colorbar()</code> everything remains in the greyscale. I have no clue what to do about it.</p>