title: How to change panel labels and x-axis sublabels in a lattice bwplot
body: <p>I'm 2 weeks into using RStudio (MacOS) so please forgive me if I'm overlooking an obvious function that would solve my problem.<br>
  As a project, I am attempting to reproduce a box plot graph with 4 plots representing Net Benefit, given disease type -- "non-severe"(0) or "severe"(1) -- as an x-axis label, and given treatment -- "talk therapy"(0) or "drug therapy"(1) -- as an x-axis sub-label.</p>
  
  <p>Here is my script so far:</p>
  
  <pre><code>tx &lt;- c(0,0,0,0,1,1,1,1)
  dztype &lt;- c(1,0,1,0,0,0,1,1)
  NBwtp1000 &lt;- c(-5500,-4000,-5000,-1000,-5000,-5000,-2800,-2000)
  require(lattice)
  bwplot(NBwtp1000 ~ paste0("Tx ", tx) | paste0("Disease Severity ", dztype),
         xlab="Talk Therapy (Tx 0) or Drug Therapy (Tx 1)", 
         ylab="Net Benefit @ wtp 1000", horizontal=FALSE)
  </code></pre>
  
  <p>If you run the code, you'll see the box-and-whisker plot: I'm almost there thanks to some informative posts on this forum about lattice's <code>bwplot</code> function.</p>
  
  <p>However, I am still far from happy with the result. I used the <code>paste0</code> function to add string descriptors to the X-axis sublabels for treatment group (originally labelled "1,2" and now showing as "Tx 0, Tx 1"), but I would ideally like those sublabels to say "Talk Therapy" and "Drug Therapy", respectively. (I simply didn't know how to do away with the existing numeric labels.)<br>
  Similarly, I would like the panel labels to say "Not Severe" where the label is currently 0 and "Severe" where the label is currently 1.</p>