Streamgraph d3v4

Mbostock's streamgraph example remade for d3 v4

For continuous data such as time series, a streamgraph can be used in place of stacked bars. This example also demonstrates path transitions to interpolate between different layouts. Streamgraph algorithm, colors, and data generation inspired by Byron and Wattenberg.

forked from mbostock's block: Streamgraph

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

body {
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  margin: auto;
  position: relative;
  width: 960px;
}

button {
  position: absolute;
  right: 10px;
  top: 10px;
}

</style>
<button onclick="transition()">Update</button>
<script src="//d3js.org/d3.v4.min.js"></script>
<script>

var n = 20, // number of layers
    m = 200, // number of samples per layer
    stack = d3.stack().keys(d3.range(n).map(function (d) { return "layer"+d; })).offset(d3.stackOffsetWiggle);

// Create empty data structures
var matrix0 = d3.range(m).map(function (d) { return { x:d }; });
var matrix1 = d3.range(m).map(function (d) { return { x:d }; });

// Fill them with random data
d3.range(n).map(function(d) { bumpLayer(m, matrix0, d); });
d3.range(n).map(function(d) { bumpLayer(m, matrix1, d); });

var layers0 = stack(matrix0),
    layers1 = stack(matrix1);

var width = 960,
    height = 500;

var x = d3.scaleLinear()
    .domain([0, m - 1])
    .range([0, width]);

var color = d3.scaleLinear()
    .range(["#aad", "#556"]);

var area = d3.area()
    .x(function(d,i) { return x(d.data.x); })
    .y0(function(d) { return y(d[0]); })
    .y1(function(d) { return y(d[1]); });

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);

svg.selectAll("path")
    .data(layers0)
  .enter().append("path")
    .attr("d", area)
    .style("fill", function() { return color(Math.random()); });

function transition() {
  d3.selectAll("path")
      .data(function() {
        var d = layers1;
        layers1 = layers0;
        return layers0 = d;
      })
    .transition()
      .duration(2500)
      .attr("d", area);
}

// Inspired by Lee Byron's test data generator.
function bumpLayer(n, matrix, layer) {

function bump(a) {
    var x = 1 / (.1 + Math.random()),
        y = 2 * Math.random() - .5,
        z = 10 / (.1 + Math.random());
    for (var i = 0; i < n; i++) {
      var w = (i / n - y) * z;
      a[i] += x * Math.exp(-w * w);
    }
  }

var a = [], i;
  var i;
  for (i = 0; i < n; ++i) a[i] = 0;
  for (i = 0; i < 5; ++i) bump(a);
  return a.forEach(function(d, i) { matrix[i]["layer"+layer]=Math.max(0, d)+1; });
}

</script>

https://d3js.org/d3.v4.min.js