title: Highlighting individual axis labels in bold using ggplot2
body: <p>I want to highlight individual axis labels in bold. I am aware of this <a href="https://stackoverflow.com/a/30036353/4308815">answer</a> by @MrFlick but I can't figure out how to do this <strong>a)</strong> for more than one item, and <strong>b)</strong> whether it's possible to use the names of the labels instead of the number of the item in that list (or expression).</p>
  
  <p>Here is an example dataset:</p>
  
  <pre><code>require(ggplot2)
  require(dplyr)
  set.seed(36)
  xx&lt;-data.frame(YEAR=rep(c("X","Y"), each=20),
                 CLONE=rep(c("A","B","C","D","E"), each=4, 2),
                 TREAT=rep(c("T1","T2","T3","C"), 10),
                 VALUE=sample(c(1:10), 40, replace=T))
  </code></pre>
  
  <p>Then I am sorting my labels according to a particular factor combination which is then supposed to be maintained across multiple panels of a plot. See my previous question <a href="https://stackoverflow.com/q/39668404/4308815">here</a>.</p>
  
  <pre><code>clone_order &lt;- xx %&gt;% subset(TREAT == "C"  &amp; YEAR == "X") %&gt;%
    arrange(-VALUE) %&gt;% select(CLONE) %&gt;% unlist()    
  xx &lt;- xx %&gt;% mutate(CLONE = factor(CLONE, levels = clone_order))
  
  ggplot(xx, aes(x=CLONE, y=VALUE, fill=YEAR)) + 
    geom_bar(stat="identity", position="dodge") +
    facet_wrap(~TREAT)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/CUbtj.png" rel="noreferrer"><img src="https://i.stack.imgur.com/CUbtj.png" alt="enter image description here"></a></p>
  
  <p>Now I want to bold <code>Clone</code> <code>A</code>, <code>B</code> and <code>E</code>. I am sure this will work somehow but I cannot figure out how. Ideally, it would be great to know how to do this by <strong>a)</strong> using the number of the item in the list/expression, and <strong>b)</strong> by using the label, e.g. <code>A</code>, <code>B</code> and <code>E</code>.</p>