Make a chart with area charts having both positive and negative y axis in dc or d3.js

Question

I want to make a chart like that shown in the image below.

By the looks of it, it looks like a composite chart, having two area charts added on top of it OR a stacked area chart. I am having difficulty in drawing this chart. When I tried with drawing stacked area chart with one stack having negative values. I got a graph where values were plotted from top to bottom but not from below the x axis. I also tried with an example of d3 streamgraph, by tweaking values of y0 and y1, but could not get this effect. I am new to D3, please help me in this regard.

Answer 1

I think this is what you want, but remember, this will work only for two series and you have to calculate y domain dynamically.

var margin = {
    top: 20,
    right: 20,
    bottom: 30,
    left: 50
  },
  width = 400 - margin.left - margin.right,
  height = 200 - margin.top - margin.bottom;

var parseDate = d3.time.format("%y-%b-%d").parse,
  formatPercent = d3.format(".0%");

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

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

var color = d3.scale.category20();

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

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

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

var stack = d3.layout.stack()
  .values(function(d) {
    return d.values;
  });

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 + ")");

var data = [{
  "date": "11-Oct-13",
  "A": 41.62,
  "B": -22.36
}, {
  "date": "11-Oct-14",
  "A": 41.95,
  "B": -22.15
}, {
  "date": "11-Oct-15",
  "A": 37.64,
  "B": -10.77
}, {
  "date": "11-Oct-16",
  "A": 37.27,
  "B": -24.65
}, {
  "date": "11-Oct-17",
  "A": 42.74,
  "B": -21.87
}];

y.domain([-24.77, 42.74]);
color.domain(d3.keys(data[0]).filter(function(key) {
  return key !== "date";
}));

data.forEach(function(d) {
  d.date = parseDate(d.date);
});

var browsers = color.domain().map(function(name) {
  return {
    name: name,
    values: data.map(function(d) {
      return {
        date: d.date,
        y: d[name],
        y0: 0
      };
    })
  };
});

x.domain(d3.extent(data, function(d) {
  return d.date;
}));

var vars = svg.selectAll(".vars")
  .data(browsers)
  .enter().append("g")
  .attr("class", "vars");

vars.append("path")
  .attr("class", "area")
  .attr("d", function(d) {
    return area(d.values);
  })
  .style("fill", function(d) {
    return color(d.name);
  });


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

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

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>