title: Omit null values in d3
body: <p>I am stuck in a project drawing a line from JSON data containing some null-values.</p>
  
  <p>I started a fiddle here: <a href="https://jsfiddle.net/scm60/pafs5x4m/" rel="nofollow noreferrer">https://jsfiddle.net/scm60/pafs5x4m/</a></p>
  
  <p>I found a possible solution here:
  <a href="https://stackoverflow.com/questions/10826180/in-d3-js-skip-append-for-null-data">In d3.js, skip append() for null data</a>, suggesting to add</p>
  
  <pre><code>circle.filter(function(d) { return d == null; }).remove()
  </code></pre>
  
  <p>But this doesn't work in my example.</p>
  
  <p>Any suggestions to this problem?</p>