title: Adding extra text to axis labels in ggplot
body: <p>I want to create nice confidence interval plot for my data frame <code>df</code>:</p>
  
  <pre><code>&gt; df 
         Estimate       Lower      Upper
  A1  0.005414976 -0.01227699 0.02310694
  A2  0.004046546 -0.01368911 0.02178220
  A3  0.002761602 -0.01491484 0.02043804
  A4 -0.002860038 -0.02049349 0.01477342
  A5 -0.004197288 -0.02178773 0.01339316
  A6  0.011004835 -0.12687561 0.14888529
  B1 -0.001077768 -0.01130327 0.00914773
  C1  0.137894575 -0.09659997 0.37238912
  D1  0.128514414 -0.10866480 0.36569363
  D2  0.168863152 -0.06347553 0.40120183
  D3  0.139645665 -0.09431216 0.37360349
  D4  0.028744139 -0.19562867 0.25311695
  </code></pre>
  
  <p>As can be seen from data set, first 6 rows represent levels of one factor, then there are two factors with only one level and the last is factor with 4 levels. I would like to display it in such a way to be clear that levels belong to one factor.</p>
  
  <p>My current plot looks like this:</p>
  
  <pre><code>ggplot(df, aes(x = rownames(df), y = Estimate, ymin = Lower, ymax = Upper)) +
  geom_pointrange() +
  geom_hline(yintercept = 0, linetype = 2) + 
  coord_flip()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/nnpFb.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/nnpFb.png" alt="enter image description here"></a></p>
  
  <p>The desired output should look like this:
  <a href="https://i.stack.imgur.com/gBDDX.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gBDDX.png" alt="enter image description here"></a></p>
  
  <p>I know there is another option how to group factors, e.g. see <a href="https://stackoverflow.com/questions/29111809/adding-text-to-axis-labels-in-ggplot">this</a>, but I would like to create something as described.</p>
  
  <p>Any help would be much appreciated!</p>