title: Bubble chart c3js
body: <p>Following the c3js documentation there is no option for Bubble chart. One workaround for that is to setup scatter plot and specify point radius, but  all of the bubbles will be the same height. </p>
  
  <pre><code>point = {
            r: function(d) {
               var num = d.value;
               return num
            },
  </code></pre>
  
  <p>Adding the value of axis inside the r solve the problem, but now the problem is how to setup very high or very low values ? For e.g if there is 1 000 000 value the whole chart will be colored. Is there any simple workarounds for that ?</p>