title: Plotting grouped continuous variable vs. binary variable
body: <p>I have a continuous response variable, and a binary predictor variable. However, that binary predictor also comes in two flavors (two different years). I'd like to create a box plot with the two years separate but in the same x-variable column.</p>
  
  <p>Here's a hypothetical dataframe setup like mine</p>
  
  <pre><code>    Wingspan     Infected     Year
      15.3         1            2015
      14.9         1            2015
      15.9         0            2016  
      15.0         1            2016
      13.8         0            2015
      16.1         0            2016
      14.2         1            2015
      15.9         1            2015 
      13.7         0            2016
      16.4         0            2016
      13.9         0            2016
      14.0         1            2015
  </code></pre>
  
  <p>It's easy for me to get an output by doing</p>
  
  <pre><code>    Model &lt;- Wingspan ~ Infected
      plot(Model)
  </code></pre>
  
  <p>However, I want the Infected columns to have 2 boxes per column, one for 2015 and one for 2016. I've tried all sorts of functions to split the data like split() and various bind functions but I can't seem to partition this data in any way and get an output. Any ideas would be appreciated.</p>