title: D3 Monotone Interpolation - Smoothing a line
body: <p>I was using the following code:</p>
  
  <pre><code>var c = d3.line()
  .interpolate("monotone")
  .x(function(d) { return x(d.date); })
  .y(function(d) { return y(d.close); }); 
  </code></pre>
  
  <p>And now that I am updating all my visual studies to D3 version 4 I can't work out how to upgrade the above interpolation.</p>
  
  <p>I want to smooth the line.</p>