D3 Examples - Stacked Area Chart

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.timeFormat - parse dates

d3.format - format percentages

d3.scaleTime - x-position encoding

d3.scaleLinear - y-position encoding

d3.scaleOrdinal, d3.schemeCategory20 - color encoding

d3.extent - compute domains

d3.stack - compute stacked y-positions

d3.axisBottom, d3.axisLeft - display axes

d3.area - display area shape

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<!DOCTYPE html>
<meta charset="utf-8">
<svg width="960" height="500"></svg>
<script src="//d3js.org/d3.v4.min.js"></script>
<script>
​
var svg = d3.select("svg"),
    margin = {top: 20, right: 20, bottom: 30, left: 50},
    width = svg.attr("width") - margin.left - margin.right,
    height = svg.attr("height") - margin.top - margin.bottom;
​
var parseDate = d3.timeParse("%Y %b %d");
​
var x = d3.scaleTime().range([0, width]),
    y = d3.scaleLinear().range([height, 0]),
    z = d3.scaleOrdinal(d3.schemeCategory10);
​
var stack = d3.stack();
​
var area = d3.area()
    .x(function(d, i) { return x(d.data.date); })
    .y0(function(d) { return y(d[0]); })
    .y1(function(d) { return y(d[1]); });
​
var g = svg.append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
​
d3.tsv("data.tsv", type, function(error, data) {
  if (error) throw error;
​
  var keys = data.columns.slice(1);
​
  x.domain(d3.extent(data, function(d) { return d.date; }));
  z.domain(keys);
  stack.keys(keys);
​
  var layer = g.selectAll(".layer")
    .data(stack(data))
    .enter().append("g")
      .attr("class", "layer");
​
  layer.append("path")
      .attr("class", "area")
      .style("fill", function(d) { return z(d.key); })
      .attr("d", area);
​
  layer.filter(function(d) { return d[d.length - 1][1] - d[d.length - 1][0] > 0.01; })
    .append("text")
      .attr("x", width - 6)
      .attr("y", function(d) { return y((d[d.length - 1][0] + d[d.length - 1][1]) / 2); })
      .attr("dy", ".35em")
      .style("font", "10px sans-serif")
      .style("text-anchor", "end")
      .text(function(d) { return d.key; });
​
  g.append("g")
      .attr("class", "axis axis--x")
      .attr("transform", "translate(0," + height + ")")
      .call(d3.axisBottom(x));
​
  g.append("g")
      .attr("class", "axis axis--y")
      .call(d3.axisLeft(y).ticks(10, "%"));
});
​
function type(d, i, columns) {
  d.date = parseDate(d.date);
  for (var i = 1, n = columns.length; i < n; ++i) d[columns[i]] = d[columns[i]] / 100;
  return d;
}
​
</script>
​
    