title: How to add keys to data that is used to display pie chart in D3?
body: <p>I have an array called countArray which simply just consists of numbers. I also have a parallel array called descArray which is essentially the keys to those values (the numbers in the countArray). In D3, I draw my pie chart using the values in countArray. </p>
  
  <pre><code>var vis = d3.select(divId).append("svg:svg").data([countArray]).attr("width",                 w).attr("height", h).append("svg:g").attr("transform", "translate(" + r + "," + r + ")");
  </code></pre>
  
  <p>When I hover over an arc in the pie chart and <code>console.log(d)</code>, I would see that the value and the key for the specific arc is the same. I want to know a way to append the key data from my <code>descArray</code> onto <code>d</code>. </p>
  
  <pre><code>            arcs.append("svg:path")
               .on("mouseover", function(d) {
                  console.log(d);
              })
  </code></pre>