title: R ggplot barplot; Fill based on two separate variables
body: <p>A picture says more than a thousand words. As you can see, my <code>fill</code> is based on the variable <code>variable</code>. </p>
  
  <p>Within each bar there is however multiple data entities (black borders) since the discrete variable <code>complexity</code> make them unique. What I am trying to find is something that makes each section of the bar more distinguishable than the current look. Preferable would be if it was something like shading.</p>
  
  <p><img src="https://i.stack.imgur.com/mW3q7.png" alt="http://s12.postimage.org/ltgs677ul/snapshot2.png"></p>
  
  <p>Here's an example (not the same dataset, since the original was imported):</p>
  
  <pre><code>dat &lt;- read.table(text = "Complexity Method Sens Spec MMC
  1 L Alpha 50 20 10
  2 M Alpha 40 30 80
  3 H Alpha 10 10 5
  4 L Beta 70 50 60
  5 M Beta 49 10 80
  6 H Beta 90 17 48
  7 L Gamma 19 5 93
  8 M Gamma 18 39 4
  9 H Gamma 10 84 74", sep = "", header=T)
  
  library(ggplot2)
  library(reshape)
  short.m &lt;- melt(dat)
  ggplot(short.m, aes(x=Method, y= value/100 , fill=variable)) + 
      geom_bar(stat="identity",position="dodge", colour="black") + 
      coord_flip()
  </code></pre>