Circle by curran

index.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>D3 Example</title>
    <script src="//cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
    <link href='https://fonts.googleapis.com/css?family=Open+Sans' rel='stylesheet' type='text/css'>
    <style>
    
      .axis text {
        font-family: 'Open Sans', sans-serif;
        font-size: 22pt;
      }
      .axis .label {
        font-size: 20pt;
      }

      .axis path, .axis line {
        fill: none;
        stroke: #000;
        shape-rendering: crispEdges;
      }

    </style>
  </head>
  <body>
    <script>
      var outerWidth = 960;
      var outerHeight = 500;
      var margin = { left: 100, top: 16, right: 100, bottom: 59 };
      var barPadding = 0.2;

      var xColumn = "name";
      var radiusColumn = "population";
      var radiusMax = 166;

      var innerWidth  = outerWidth  - margin.left - margin.right;
      var innerHeight = outerHeight - margin.top  - margin.bottom;

      var svg = d3.select("body").append("svg")
        .attr("width",  outerWidth)
        .attr("height", outerHeight);
      var g = svg.append("g")
        .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
      var xAxisG = g.append("g")
        .attr("class", "x axis")
        .attr("transform", "translate(0," + innerHeight + ")");

      var xScale = d3.scale.ordinal().rangePoints([0, innerWidth], barPadding);
      var radiusScale = d3.scale.sqrt().range([0, radiusMax]);

      // Use a modified SI formatter that uses "B" for Billion.
      var siFormat = d3.format("s");
      var customTickFormat = function (d){
        return siFormat(d).replace("G", "B");
      };

      var xAxis = d3.svg.axis().scale(xScale).orient("bottom")
        .outerTickSize(0);

      function render(data){

        xScale.domain(       data.map( function (d){ return d[xColumn]; }));
        radiusScale.domain([0, d3.max(data, function (d){ return d[radiusColumn]; })]);

        xAxisG.call(xAxis);

        var circles = g.selectAll("circle").data(data);
        circles.enter().append("circle")
          .attr("width", xScale.rangeBand());
        circles
          .attr("cx", function (d){ return xScale(d[xColumn]); })
          .attr("cy", innerHeight / 2)
          .attr("r", function (d){ return radiusScale(d[radiusColumn]); });
        circles.exit().remove();
      }

      function type(d){
        d.population = +d.population;
        return d;
      }

      d3.csv("populationByCountry2015.csv", type, render);

    </script>
  </body>
</html>