title: Creating a stacked bar chart centered on zero using ggplot
body: <p>I'm currently working with a stacked horizontal bar graph chart using ggplot2 in R.</p>
  
  <p>This is my R code:</p>
  
  <pre><code>ggplot(results, aes(x=Protocol, y=Time, fill=Phase)) + 
    geom_bar(stat="identity") + coord_flip()
  </code></pre>
  
  <p>And it produces this graph:
  <img src="https://i.imgur.com/5xShfif.jpg" alt="Example Graph"></p>
  
  <p>I want to center this chart so that Phase 1 and 2 are on the left and Phase 3 and 4 are on the right.</p>
  
  <p>Here is a rough idea of what I'm looking for. But imagine the center line is time 0, and time goes positive in either direction:
  <img src="https://i.imgur.com/WA6vNq2.jpg" alt="Example of Goal"></p>
  
  <p>I'm thinking I should make two graphs back to back?</p>