title: R plot using ggplot facet_grid add legend
body: <p>Using <code>ggplot</code> and <code>faced_grid</code>, I have a problem to visualize the entire name of type1 variable. The name is too long. How I can add a legend for avoid this problem? </p>
  
  <pre><code>DF &lt;- data.frame("value" =  runif(50, 0, 1),
                   "type1" = c(rep("AAAAAAAAAAAAAAAAAAAAAA", 25), 
                               rep("BBBBBBBBBBBBBBBBB", 25)),
                   "type2" = rep(c("c", "d"), 25), 
                   "number" = rep(2:6, 10))
  
  ggplot(DF, aes(y = value, x = type1)) + 
    geom_boxplot(alpha = .3) + 
    ggtitle("TITLE") + 
    facet_grid(type2 ~ number)
  </code></pre>
  
  <p>This is the results: </p>
  
  <p><a href="https://i.stack.imgur.com/fiUzc.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fiUzc.png" alt="CODE RESULT"></a></p>