title: Hide null values bars on Google Chart
body: <p>I need to show, on a bar chart, this values:</p>
  
  <pre><code>Project     2013-01  2013-02  2013-03  2013-04  2013-05  2013-06
  A            15       null     null     null     null     null
  B            null     12       null     null     null     null
  C            null     null     null     10       null     null
  D            null     13       null     null     null     null
  E            null     null     11       null     null     null
  F            null     null     null     null     17       null
  G            null     null     null     null     null     20
  </code></pre>
  
  <p>Currently I'm showing the projects as series, and the months in the X axis.</p>
  
  <p>The problem is: each project will only have value to one month, but a month can have values from several projects, so a common bar chart, with several projects, will have a bunch of small bars, because of the blank spaces of the null values.</p>
  
  <p>Is there a way to hide these null columns?</p>
  
  <p>Or a better way to show this data?</p>