title: Exclude zero values from a C3.js bar chart
body: <p>Let's take for example following chart <a href="http://c3js.org/samples/chart_bar.html" rel="noreferrer">http://c3js.org/samples/chart_bar.html</a>
  but replace columns data with the data below:</p>
  
  <pre><code>var chart = c3.generate({
      data: {
          columns: [
              ['data1', 30, 0, 100, 0, 150, 250],
              ['data2', 130, 0, 140, 200, 0, 50]
          ],
          type: 'bar'
      },
      bar: {
          width: {
              ratio: 0.5 // this makes bar width 50% of length between ticks
          }
          // or
          //width: 100 // this makes bar width 100px
      }
  });
  
  setTimeout(function () {
      chart.load({
          columns: [
              ['data3', 130, -150, 200, 300, -200, 100]
          ]
      });
  }, 1000);
  </code></pre>
  
  <p>As we see we have a lot of white space or ZERO value bars, how can we remove it and remove white space. (not hide, I know how to hide it with CSS)</p>
  
  <p><a href="http://i.stack.imgur.com/GCfGW.png" rel="noreferrer">Image example, what should be removed</a></p>