title: Stacked bar chart across multiple columns
body: <p>I managed to transform my initial dataset into this form:</p>
  
  <pre><code>   ElemId total_count coef_true coef_false coef_ratio
   1  a1           2         2          0          1
   2  a2           4         4          0          1
   3  a3           1         1          0          1
   4  a4           5         5          0          1
   5  a5           1         1          5          1
   6  a6           4         4          0          1
   7  a7           4         4          3          1
   8  a8           2         2          2          1
   9  a9           3         3          1          1
  10  a10           1         1          4          1
  </code></pre>
  
  <p>Right now what am I trying to achieve is to plot stacked bar chart showing the coef_true and coef_false on single bars using ggplot, <em>while preserving order by coef_ratio</em>. Is there a way to do it without further transforming the dataset?</p>
  
  <p><strong>EDIT.</strong> Modifying data is OK, although I tried using melt with <code>melt(valves, measure.vars=c("init_true", "init_false"))</code> and the bar chart seems to loose ordering of coef_ratio.</p>