title: D3 Plot array of circles
body: <p>I've tried the circle plot example as the following:</p>
  
  <pre><code>  var x=20, y=20, r=50;
    var sampleSVG = d3.select("#viz")
    .append("svg")
    .attr("width", 800)
    .attr("height", 600);    
  
    sampleSVG.append("circle")
    .style("stroke", "gray")
    .style("fill", "white")
    .attr("r",  r)
    .attr("cx", x)
    .attr("cy", y);
  </code></pre>
  
  <p>But  I want to figure out how to plot without a loop a sequence of circles from an array like:</p>
  
  <pre><code>  data = [
            [10,20,30],
            [20,30,15],
            [30,10,25]
           ];
  </code></pre>