title: Ordering boxplots from different dataframes manually on the same graph
body: <p>How can I manually order the boxplots, for instance, switching boxplot a with c, in the following example?</p>
  <pre><code>library(ggplot2)
  df1 &lt;- data.frame(a=c(5, 5, 6, 6, 8, 9, 13, 15,
                        11, 11, 12, 14, 15, 19, 22, 24,
                        19, 23, 23, 23, 24, 26, 29, 33))
  
  df2 &lt;- data.frame(b=c(5, 5, 6, 6, 8, 9, 13, 15,
                        11, 18, 12, 14, 50, 19, 22, 24,
                        19, 23, 23, 23, 24, 28, 31, 33))
  
  
  df3 &lt;- data.frame(c=c(5, 5, 6, 6, 8, 9, 13, 15,
                        11, 11, 12, 14, 30, 19, 22, 24,
                        19, 23, 23, 23, 24, 26, 29, 33))
  
  
  ggplot() +
    geom_boxplot(data = df1, aes(x = 'a', y=a)) +
    geom_boxplot(data = df2, aes(x = 'b', y=b)) + 
    geom_boxplot(data = df3, aes(x = 'c', y=c)) 
  </code></pre>
  <p><a href="https://i.stack.imgur.com/lfviv.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lfviv.png" alt="enter image description here" /></a></p>