Week10/stacked_area_invert.html

<!DOCTYPE html>
<!-- mod of Mike Bostock's block http://bl.ocks.org/mbostock/3020685 -->
<meta charset="utf-8">
<style>

body {
  font: 12px sans-serif;
  padding: 50px;
}

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

.tooltip {
  position: absolute;
  z-index: 10;
}

.tooltip p {
  background-color: white;
  border: gray 1px solid;
  padding: 2px;
  max-width: 180px;
}

</style>
<body>

  <h2>Stacked Area Chart of South African Child Deaths from Measles</h2>

  <p><a href="http://apps.who.int/gho/data/node.main.ghe100-by-cause?lang=en">WHO data</a>, deaths of children 0-4 years old in selected South African countries.</p>

  <p>This example shows how to use invert and bisectors to get the approx values for the data at each point, for the tooltip.  It's not very exact.</p>

  <div id="chart"></div>

  <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.6/d3.min.js"></script>
  <script>

var formatDate = d3.time.format("Year %Y");

var fullwidth = 960,
  fullheight = 500;

var margin = {top: 20, right: 30, bottom: 30, left: 60},
    width = fullwidth - margin.left - margin.right,
    height = fullheight - margin.top - margin.bottom;

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

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

var colorScale = d3.scale.category20b();

var xAxis = d3.svg.axis()
    .scale(xScale)
    .orient("bottom")
    .ticks(10);

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

var stack = d3.layout.stack()
    .offset("zero") // try "silhouette" next, that's a streamgraph!
    //.order("inside-out")  // try this and see what you think
    .values(function(d) { return d.values; })
    .x(function(d) { return formatDate.parse(d.Year);})
    .y(function(d) { return +d.Measles; });

// use the result of the stack to draw the shapes using area
var area = d3.svg.area()
    .interpolate("cardinal")
    .x(function(d) { return xScale(formatDate.parse(d.Year)); })
    .y0(function(d) { return yScale(d.y0); })
    .y1(function(d) { return yScale(d.y0 + d.y); });

var svg = d3.select("#chart").append("svg")
    .attr("width", fullwidth )
    .attr("height", fullheight)
  .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var tooltip = d3.select("body").append("div").attr("class", "tooltip");

d3.csv("data/deaths_04yearsold_excerpt.csv", function(error, data) {

  if (error) { console.log(error); };

  var dataset =  d3.nest()
    .key(function(d) {
      return d.Country;
    })
    .sortKeys(d3.descending)  // alphabetic order from top layer - Zambia at bottom
    .sortValues(function (a, b) { return formatDate.parse(a.Year) - formatDate.parse(b.Year)})
    .entries(data);

  console.log(dataset);

  var layers = stack(dataset);
  console.log("layers", layers);  // it adds a y and y0 to the data values.

  // reset these after doing the layer stacking.
  xScale.domain(d3.extent(data, function(d) { return formatDate.parse(d.Year); }));
  yScale.domain([0, d3.max(data, function(d) { return d.y0 + d.y; })]); // highest combo

  var layers = svg.selectAll(".layer")
      .data(layers);

  layers.enter().append("path")
      .attr("class", "layer")
      .attr("d", function(d) { return area(d.values); })
      .style("fill", function(d, i) { return colorScale(i); }); // just count off

  layers.on("mouseover", mouseover)
    .on("mousemove", mousemove)
    .on("mouseout", mouseout);

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

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


  function mouseover(d) {

    d3.select(this)
      .transition()
      .style("stroke", "black");

  }

  function mousemove(d) {

    // we put the tooltip text in here, because otherwise it won't update with mouse pos.

    var bisect = d3.bisector(function(d) {
      return d.Year;
    }).left;

    var mouseDate = xScale.invert(d3.mouse(this)[0]);
    var year = mouseDate.getFullYear(); // just use the year for the tooltip

    // formatDate turns it back into the format in d.values, so it can be looked up!
    var index = bisect(d.values, formatDate(mouseDate), 0, d.values.length-1);
    console.log(index);

    var value = d.values[index].Measles; // the illness on the y axis

    tooltip
      .style("display", null) // this removes the display none setting from it
      .html("<p>Country: " + d.key +
        "<br>Year: " + year +
        "<br>Measles deaths: " + value + "</p>");

    tooltip
      .style("top", (d3.event.pageY - 10) + "px" )
      .style("left", (d3.event.pageX + 10) + "px");
    }

  function mouseout(d) {
    d3.select(this)
      .transition()
      .style("stroke", "none");

    tooltip.style("display", "none");  // this sets it to invisible!
  }


});


</script>