Contour Plot

An example of the d3.geom.contour plugin.

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

.axis text {
  font: 10px sans-serif;
}

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

.axis path {
  display: none;
}

.isoline {
  fill: none;
  stroke: #fff;
}

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

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

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

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

var color = d3.scale.linear()
    .domain([95, 115, 135, 155, 175, 195])
    .range(["#0a0", "#6c0", "#ee0", "#eb4", "#eb9", "#fff"]);

var xAxis = d3.svg.axis()
    .scale(x)
    .orient("bottom")
    .ticks(20);

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

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.json("readme-heatmap.json", function(error, heatmap) {
  if (error) throw error;

var dx = heatmap[0].length,
      dy = heatmap.length;

x.domain([0, dx]);
  y.domain([0, dy]);

svg.selectAll(".isoline")
      .data(color.domain().map(isoline))
    .enter().append("path")
      .datum(function(d) { return d3.geom.contour(d).map(transform); })
      .attr("class", "isoline")
      .attr("d", function(d) { return "M" + d.join("L") + "Z"; })
      .style("fill", function(d, i) { return color.range()[i]; });

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

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

function isoline(min) {
    return function(x, y) {
      return x >= 0 && y >= 0 && x < dx && y < dy && heatmap[y][x] >= min;
    };
  }

function transform(point) {
    return [point[0] * width / dx, point[1] * height / dy];
  }
});

</script>

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