title: Multiple columns on x-axis in R
body: <p>I'm quite new to R, and there has been a question similar to mine asked before, however it doesn't quite get to what I need.</p>
  
  <p>I have a table as follows:</p>
  
  <p><a href="https://i.stack.imgur.com/yA8Qi.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yA8Qi.png" alt="enter image description here"></a></p>
  
  <p>I wish to plot the <code>Value,</code> and <code>Threshold</code> alongside each other on the X-axis for each metric, so effectively, I will have three pairs of plots on the X-axis. I have attempted to use <code>reshape2</code> and <code>ggplot2</code> for this as follows:</p>
  
  <pre><code>library(reshape2)
  df &lt;- melt(msi, id.vars="Average Metric Value (Abbr)")
  # I get an error message, but the output seems ok.
  
  library(ggplot2)
  ggplot(df, aes(x="Average Metric Value (Abbr)", y=value, fill=variable)) + geom_bar(stat='identity', position='dodge')
  </code></pre>
  
  <p>The output graph is as follows: </p>
  
  <p><a href="https://i.stack.imgur.com/5N1Fh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/5N1Fh.png" alt="enter image description here"></a></p>
  
  <p>I'm sure I can work out how to separate each of the three pairs later, but as you can see, I don't have the metric names for each of the three pairs along the x-axis, and I am missing the first "Value" bar, presumably because it equals the same as the second and I am only getting unique values plotted. </p>
  
  <p>How do I get around that and have the names of each metric beneath each pairs of values?</p>