D3 Examples - Grouped Bar Chart

Grouped Bar Chart - Age

This visualization shows the number of people who have attained a college degree grouped by population age 25 and over.

Data Source: Table 1A of What It's Worth: Field of Training and Economic Status, US Census Bureau, Survey of Income and Program Participation, 2008 Panel.

Visualization based on Mike Bostock's Grouped Bar chart example. Features include:

d3.csv - load and parse data

d3.scale.ordinal - x-position encoding and color encoding

d3.scale.linear - y-position encoding

d3.format - SI prefix formatting (e.g., “10M” for 10,000,000)

d3.max - compute domains

d3.keys - compute column names

d3.svg.axis - display axes

xxxxxxxxxx
 
<!DOCTYPE html>
Homework 1
<!-- Based on Mike Bostocks grouped bar chart example -->
<style>
​
  body {
    font: 12px sans-serif;
  }
  
    .domain {
  display: none;
    }
  
  .axis path {
    fill: #ff;
    stroke: #ff;
  }
  
  .axis .tick line {
    stroke-width: 1;
    stroke: #ff;
  }
  .axis line {
    stroke-width: 1px;
    fill: #ff;
    stroke: #ff;
    shape-rendering: crispedges;
  }
  
</style>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>  
var svg = d3.select("svg"),
    margin = {top: 20, right: 20, bottom: 30, left: 65},
    width = +svg.attr("width") - margin.left - margin.right,
    height = +svg.attr("height") - margin.top - margin.bottom,
    g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");
​
var x0 = d3.scaleBand()
    .rangeRound([0, width])
    .paddingInner(0.1);
​
var x1 = d3.scaleBand()
    .padding(0.05);
​
var y = d3.scaleLinear()
    .rangeRound([height, 0]);
​
var z = d3.scaleOrdinal(d3.schemeCategory10);
​
var divTooltip = d3.select("body").append("div").attr("class", "toolTip");
  // Read and map CSV
d3.csv("Table 1A.csv", function(d, i, columns) {
  for (var i = 1, n = columns.length; i < n; ++i) d[columns[i]] = +d[columns[i]];
  return d;
}, function(error, data) {
  if (error) throw error;
​
  var keys = data.columns.slice(1);
  
  x0.domain(data.map(function(d) { return d.Education; }));
  x1.domain(keys).rangeRound([0, x0.bandwidth()]);
  y.domain([0, d3.max(data, function(d) { return d3.max(keys, function(key) { return d[key]; }); })]).nice();
​
    // Bars
  g.append("g")
    .selectAll("g")
    .data(data)
    .enter().append("g")
      .attr("transform", function(d) { return "translate(" + x0(d.Education) + ",0)"; })
    .selectAll("rect")
    .data(function(d) { return keys.map(function(key) { return {key: key, value: d[key]}; }); })
    .enter().append("rect")
      .attr("x", function(d) { return x1(d.key); })
      .attr("y", function(d) { return y(d.value); })
      .attr("width", x1.bandwidth())
      .attr("height", function(d) { return height - y(d.value); })
      .attr("fill", function(d) { return z(d.key); });
  
  //Axis  
  g.append("g")
      .attr("class", "axis")
      .attr("transform", "translate(0," + height + ")")
      .call(d3.axisBottom(x0));
​
  g.append("g")
      .attr("class", "axis")
      .call(d3.axisLeft(y))
    .append("text")
      .attr("x", 0 - (height / 2))
        .attr("y", 15 - margin.left)
      .attr("dy", "0.72em")
      .attr("fill", "#000")
      .attr("font-weight", "bold")
      .attr("text-anchor", "end")
        .attr("transform", "rotate(-90)")
      .text("Population in thousands");
​
  //Legend
  var legend = g.append("g")
      .attr("font-family", "sans-serif")
      .attr("font-size", 10)
      .attr("text-anchor", "end")
    .selectAll("g")
    .data(keys.slice().reverse())
    .enter().append("g")
      .attr("transform", function(d, i) { return "translate(0," + i * 20 + ")"; });
​
  legend.append("rect")
      .attr("x", width - 19)
      .attr("width", 19)
      .attr("height", 19)
      .attr("fill", z);
​
  legend.append("text")
      .attr("x", width - 24)
      .attr("y", 9.5)
      .attr("dy", "0.32em")
      .text(function(d) { return d; });
});
​
    
</script>
    