title: Violin chart in D3
body: <p>Any ideas on where to even begin with making a violin chart using d3?  Does it exist already?</p>
  
  <p>I've looked around and have figured out how to do it using ggplot2 and was hoping there'd be a ready-made example that I could learn from but haven't found one yet.  </p>
  
  <p>I suppose I could do a really painful process of making various size bars on top of each other, or taking a distribution, rotating it and mirroring it.  But surely there's a better way.</p>