title: Filter/select specific type of data
body: <p>I would like to select elements in my data array that have a specific paramter value. </p>
  
  <p>ex: </p>
  
  <pre><code>[{type: "suv", value:10},{type: "suv", value:20},{type: "berline", value:15},{type: "berline", value:5}]
  </code></pre>
  
  <p>So, how would I only have the <code>type:"suv"</code> to be taken into account when plotting my value data?</p>
  
  <p>The only similar thing I could find is selectAll, but it seems to only select elements in the UI (?)</p>
  
  <p>Bear with me if this is simpler, I'm not too used to d3.js, and the information on the subject is rare.</p>