Bar chart from external JSON file

A simple bar chart build using data from an external JSON file.

forked from Jverma's block: Bar chart from external JSON file

<!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.v3.min.js"></script>
<script>

var n = 10, // number of layers
    m = 200, // number of samples per layer
    stack = d3.layout.stack().offset("wiggle"),
    layers0 = stack(d3.range(n).map(function() { return bumpLayer(m); })),
    layers1 = stack(d3.range(n).map(function() { return bumpLayer(m); }));

var width = 960,
    height = 500;

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

var y = d3.scale.linear()
    .domain([0, d3.max(layers0.concat(layers1), function(layer) { return d3.max(layer, function(d) { return d.y0 + d.y; }); })])
    .range([height, 0]);

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

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

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) {

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;
  for (i = 0; i < n; ++i) a[i] = 0;
  for (i = 0; i < 5; ++i) bump(a);
  return a.map(function(d, i) { return {x: i, y: Math.max(0, d)}; });
}

</script>

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