title: How do I limit the range of the viridis colour scale?
body: <p>I have two sets of data, which I want to present using a heat map with the viridis color scale. For the first data set, my values range from 0 to 1.2 and I can easily see the differences I want to see. However my second data set has some outliers, resulting in a range from 0 to 2. Now it's harder to see the differences in the interesting range between 0 and 1 and it's more diffucult to compare the two images directly. Is there a possibility to show the data from 0 to 1.2 using the viridis colour scale while showing the higher values in yellow ("highest" colour of the viridis scale)?
  Here is an example:</p>
  
  <pre><code>library(viridis)
  
  #Create Data
  DataSet1 &lt;- expand.grid(x = 0:5, y = 0:5)
  DataSet1$z &lt;- runif(36, 0, 1.2)
  
  DataSet2 &lt;- expand.grid(x = 0:5, y = 0:5)
  DataSet2$z &lt;- runif(36, 0, 2)
  
  #Plot Data
  ggplot(DataSet1, aes(x, y, fill = z)) + 
    geom_tile() +
    scale_fill_viridis() +
    geom_text(aes(label = round(z, 2)), size = 2)
  </code></pre>
  
  <p>DataSet1: Differences between 0.5 and 0.7 are easy to see</p>
  
  <p><a href="https://i.stack.imgur.com/6uKuX.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/6uKuX.jpg" alt="enter image description here"></a></p>
  
  <pre><code>ggplot(DataSet2, aes(x, y, fill = z)) + 
    geom_tile() +
    scale_fill_viridis() +
    geom_text(aes(label = round(z, 2)), size = 2)
  </code></pre>
  
  <p>DataSet2: Differences between 0.5 and 0.7 are diffucult to see</p>
  
  <p><a href="https://i.stack.imgur.com/CD8tC.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/CD8tC.jpg" alt="enter image description here"></a></p>