title: Tableau: A bar which shows the difference between
body: <p>I have the following data for which i need to create a bar chart as shown in the picture in tableau:</p>
  
  <p><img src="https://i.stack.imgur.com/E7wEs.png" /></p>
  
  <pre><code>Brand   Sales   week
  A   12  1
  B   20  1
  C   14  1
  A   12  2
  B   22  2
  C   16  2
  A   18  3
  B   16  3
  C   27  3
  </code></pre>
  
  <p>My chart must contain sales in rows and week in columns. For every week, I must show three bars:</p>
  
  <ul>
  <li><ol>
  <li>Sales for Brand A (A is always fixed)</li>
  </ol></li>
  <li><ol start="2">
  <li>sales for Brand B/ Brand C (B/C:- Its a parameter selection)</li>
  </ol></li>
  <li><ol start="3">
  <li>Difference between sales of these two</li>
  </ol></li>
  </ul>