Stacked Charts

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Protovis includes flexible layouts that can simplify the implementation of common visualization techniques. This example uses pv.Layout.Stack to stack area marks vertically with a zero baseline. The stack layout can also be used to stack bars or columns as well as areas, and supports several streamgraph algorithms.

Next: Grouped Charts

Source

<html>
  <head>
    <title>Stacked Area Chart</title>
    <link type="text/css" rel="stylesheet" href="ex.css?3.2"/>
    <script type="text/javascript" src="../protovis-r3.2.js"></script>
    <script type="text/javascript" src="stack.js"></script>
    <style type="text/css">

#fig {
  width: 430px;
  height: 225px;
}

    </style>
  </head>
  <body><div id="center"><div id="fig">
    <script type="text/javascript+protovis">

/* Sizing and scales. */
var w = 400,
    h = 200,
    x = pv.Scale.linear(0, 9.9).range(0, w),
    y = pv.Scale.linear(0, 14).range(0, h);

/* The root panel. */
var vis = new pv.Panel()
    .width(w)
    .height(h)
    .bottom(20)
    .left(20)
    .right(10)
    .top(5);

/* X-axis and ticks. */
vis.add(pv.Rule)
    .data(x.ticks())
    .visible(function(d) d)
    .left(x)
    .bottom(-5)
    .height(5)
  .anchor("bottom").add(pv.Label)
    .text(x.tickFormat);

/* The stack layout. */
vis.add(pv.Layout.Stack)
    .layers(data)
    .x(function(d) x(d.x))
    .y(function(d) y(d.y))
  .layer.add(pv.Area);

/* Y-axis and ticks. */
vis.add(pv.Rule)
    .data(y.ticks(3))
    .bottom(y)
    .strokeStyle(function(d) d ? "rgba(128,128,128,.2)" : "#000")
  .anchor("left").add(pv.Label)
    .text(y.tickFormat);

vis.render();

    </script>
  </div></div></body>
</html>

Data

var data = pv.range(4).map(function() {
    return pv.range(0, 10, .1).map(function(x) {
        return {x: x, y: Math.sin(x) + Math.random() * .5 + 2};
      });
  });