title: How to limit the display limits of a colorbar in matplotlib
body: <p>I am plotting 3 channels of my time series measurements which are more or less centered around (-80). Missing values are filled with (-50) so that they get a bright yellow color and contrast with the rest of the plot. It has no meaning numerically. See the figure and the code below: </p>
  
  <pre><code>f, ax = plt.subplots(figsize=(12.5, 12.5))
  sns.heatmap(df.loc[:, ['Ch2', 'Ch3', 'Ch1']].fillna(-50)[:270], cmap='viridis', yticklabels=27, cbar=True, ax=ax)
  </code></pre>
  
  <p>How can I keep the color range but limit the display scale (i.e the heatmap should stay the same but the color bar ranges only from -70 to -90)?
  <a href="https://i.stack.imgur.com/zYbXc.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/zYbXc.png" alt="enter image description here"></a>
  (Note that the question of how to <a href="https://stackoverflow.com/questions/33779748/set-max-value-for-color-bar-on-seaborn-heatmap">Set Max value for color bar on seaborn heatmap</a> has already been answered and it is not what I am aiming at, I want vmin and vmax to stay just as they are). </p>