Colored bubble plot in d3.js




This post follows the previous basic bubble plot. It extends it, adding the information of a fourth variable mapped to the bubble color. Visit the bubble plot section for more examples.


Bubbleplot section

Steps:

  • Almost the same as the previous basic bubble chart

  • A new categoric color scale is added for the color using scaleOrdinal()

  • Color palette comes from colorBrewer. Read more about color management in d3 here.
<!DOCTYPE html>
<meta charset="utf-8">

<!-- Load d3.js -->
<script src="https://d3js.org/d3.v4.js"></script>

<!-- Load color scale -->
<script src="https://d3js.org/d3-scale-chromatic.v1.min.js"></script>

<!-- Create a div where the graph will take place -->
<div id="my_dataviz"></div>


<script>

// set the dimensions and margins of the graph
var margin = {top: 10, right: 20, bottom: 30, left: 50},
    width = 500 - margin.left - margin.right,
    height = 420 - margin.top - margin.bottom;

// append the svg object to the body of the page
var svg = d3.select("#my_dataviz")
  .append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform",
          "translate(" + margin.left + "," + margin.top + ")");

//Read the data
d3.csv("https://raw.githubusercontent.com/holtzy/data_to_viz/master/Example_dataset/4_ThreeNum.csv", function(data) {

  // Add X axis
  var x = d3.scaleLinear()
    .domain([0, 12000])
    .range([ 0, width ]);
  svg.append("g")
    .attr("transform", "translate(0," + height + ")")
    .call(d3.axisBottom(x));

  // Add Y axis
  var y = d3.scaleLinear()
    .domain([35, 90])
    .range([ height, 0]);
  svg.append("g")
    .call(d3.axisLeft(y));

  // Add a scale for bubble size
  var z = d3.scaleLinear()
    .domain([200000, 1310000000])
    .range([ 4, 40]);

  // Add a scale for bubble color
  var myColor = d3.scaleOrdinal()
    .domain(["Asia", "Europe", "Americas", "Africa", "Oceania"])
    .range(d3.schemeSet2);

  // Add dots
  svg.append('g')
    .selectAll("dot")
    .data(data)
    .enter()
    .append("circle")
      .attr("cx", function (d) { return x(d.gdpPercap); } )
      .attr("cy", function (d) { return y(d.lifeExp); } )
      .attr("r", function (d) { return z(d.pop); } )
      .style("fill", function (d) { return myColor(d.continent); } )
      .style("opacity", "0.7")
      .attr("stroke", "white")
      .style("stroke-width", "2px")

  })
</script>

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