title: How to reorder the items in a legend?
body: <p>I'm trying to change the order in which legend items appear.  I've spent about an hour at this, with no results.</p>
  
  <p>Here's an example setup:</p>
  
  <pre><code>library(ggplot2)
  set.seed(0)
  d &lt;- data.frame(x = runif(3), y = runif(3), a = c('1', '3', '10'))
  </code></pre>
  
  <p>And here's one of the many things I've tried:</p>
  
  <pre><code>ggplot(d, aes(x = x, y = y)) + 
      geom_point(size=7, aes(color = a, order = as.numeric(a)))
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/Nzc1B.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Nzc1B.png" alt="enter image description here"></a></p>
  
  <p>(My naive hope, of course, was that the legend items would be shown in the numeric order: 1, 3, 10.)</p>