D3 Examples - streamgraph-randomData

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<!DOCTYPE html>
<!DOCTYPE html>
<meta charset="utf-8">
<title>Streamgraph</title>
<style>
​
button {
  position: absolute;
  left: 10px;
  top: 10px;
}
​
</style>
<button onclick="transition()">Update</button>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>
​
var n = 20, // number of layers
    m = 200, // number of samples per layer
    k = 10; // number of bumps per layer
​
var stack = d3.stack().keys(d3.range(n)).offset(d3.stackOffsetWiggle),
    layers0 = stack(d3.transpose(d3.range(n).map(function() { return bumps(m, k); }))),
    layers1 = stack(d3.transpose(d3.range(n).map(function() { return bumps(m, k); }))),
    layers = layers0.concat(layers1);
​
var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height");
​
var x = d3.scaleLinear()
    .domain([0, m - 1])
    .range([0, width]);
​
var y = d3.scaleLinear()
    .domain([d3.min(layers, stackMin), d3.max(layers, stackMax)])
    .range([height, 0]);
​
var z = d3.interpolateCool;
​
var area = d3.area()
    .x(function(d, i) { return x(i); })
    .y0(function(d) { return y(d[0]); })
    .y1(function(d) { return y(d[1]); });
​
svg.selectAll("path")
  .data(layers0)
  .enter().append("path")
    .attr("d", area)
    .attr("fill", function() { return z(Math.random()); });
​
function stackMax(layer) {
  return d3.max(layer, function(d) { return d[1]; });
}
​
function stackMin(layer) {
  return d3.min(layer, function(d) { return d[0]; });
}
​
function transition() {
  var t;
  d3.selectAll("path")
    .data((t = layers1, layers1 = layers0, layers0 = t))
    .transition()
      .duration(2500)
      .attr("d", area);
}
​
// Inspired by Lee Byron’s test data generator.
function bumps(n, m) {
  var a = [], i;
  for (i = 0; i < n; ++i) a[i] = 0;
  for (i = 0; i < m; ++i) bump(a, n);
  return a;
}
​
function bump(a, n) {
  var x = 1 / (0.1 + Math.random()),
      y = 2 * Math.random() - 0.5,
      z = 10 / (0.1 + Math.random());
  for (var i = 0; i < n; i++) {
    var w = (i / n - y) * z;
    a[i] += x * Math.exp(-w * w);
  }
}
​
</script>
    