Stacked Area Chart

This stacked area chart is constructed from a TSV file storing the market share of several popular web browsers over the last year. Data is from Clicky Web Analytics. The chart employs conventional margins and a number of D3 features:

d3.tsv - load and parse data
d3.time.format - parse dates
d3.format - format percentages
d3.time.scale - x-position encoding
d3.scale.linear - y-position encoding
d3.scale.category20, a d3.scale.ordinal - color encoding
d3.extent and d3.max - compute domains
d3.layout.stack - compute stacked y-positions
d3.keys - compute column names
d3.svg.axis - display axes
d3.svg.area - display area shape

forked from mbostock's block: Stacked Area Chart

<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  font: 10px sans-serif;
}

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

.browser text {
  text-anchor: end;
}

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>

var margin = {top: 20, right: 20, bottom: 30, left: 50},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var parseDate = d3.time.format("%y-%b-%d").parse,
    formatPercent = d3.format(".0%");

var x = d3.time.scale()
    .range([0, width]);

var y = d3.scale.linear()
    .range([height, 0]);

var color = d3.scale.category20();

var xAxis = d3.svg.axis()
    .scale(x)
    .orient("bottom");

var yAxis = d3.svg.axis()
    .scale(y)
    .orient("left")
    .tickFormat(formatPercent);

var area = d3.svg.area()
    .x(function(d) { return x(d.date); })
    .y0(function(d) { return y(d.y0); })
    .y1(function(d) { return y(d.y0 + d.y); });

var stack = d3.layout.stack()
    .values(function(d) { return d.values; });

var svg = d3.select("body").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 + ")");

d3.tsv("data.tsv", function(error, data) {
  if (error) throw error;

color.domain(d3.keys(data[0]).filter(function(key) { return key !== "date"; }));
  
  data.forEach(function(d) {
    d.date = parseDate(d.date);
  });
  
  console.log(data);

var browsers = stack(color.domain().map(function(name) {
    return {
      name: name,
      values: data.map(function(d) {
        return {date: d.date, y: d[name] / 100};
      })
    };
  }));

x.domain(d3.extent(data, function(d) { return d.date; }));

var browser = svg.selectAll(".browser")
      .data(browsers)
    .enter().append("g")
      .attr("class", "browser");

browser.append("path")
      .attr("class", "area")
      .attr("d", function(d) { return area(d.values); })
      .style("fill", function(d) { return color(d.name); });

browser.append("text")
      .datum(function(d) { return {name: d.name, value: d.values[d.values.length - 1]}; })
      .attr("transform", function(d) { return "translate(" + x(d.value.date) + "," + y(d.value.y0 + d.value.y / 2) + ")"; })
      .attr("x", -6)
      .attr("dy", ".35em")
      .text(function(d) { return d.name; });

svg.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);

svg.append("g")
      .attr("class", "y axis")
      .call(yAxis);
});

</script>

https://d3js.org/d3.v3.min.js