title: How to add single label per svg element?
body: <p>I'm attempting to add a simple data label to <a href="http://bl.ocks.org/mbostock/1305111" rel="nofollow">this example</a> </p>
  
  <pre><code>svg.selectAll("text")
          .data(data)
          .enter()
          .append("text")
          .attr("text-anchor", "middle")
          .attr("fill", "red")
          .text(function(d) { return d[0] });
  </code></pre>
  
  <p>but it writes all the data in all labels which I think is because the graph is split over several individual svg-elements. How can I fix this?</p>
  
  <p><a href="http://jsfiddle.net/sPZ55/" rel="nofollow">Fiddle</a></p>