lgrammel/button.css

## button.css
button {
  font: 14px Helvetica Neue;
  background-color: #222;
  background-image: -moz-linear-gradient(top, rgba(255,255,255,.25), rgba(255,255,255,.11));
  background-image: -webkit-gradient(linear,left top,left bottom,color-stop(0, rgba(255,255,255,.25)),color-stop(1, rgba(255,255,255,.11)));
  background-image: -webkit-linear-gradient(rgba(255,255,255,.25), rgba(255,255,255,.11));
  color: #fff;
  text-rendering: optimizeLegibility;
  text-shadow: 0 -1px 1px #222;
  padding: 6px 10px 6px 10px;
  border: 0;
  border-radius: 0;
  border-bottom: 1px solid #222;
  margin: 0;
  -moz-box-shadow: 0 1px 3px #999;
  -webkit-box-shadow: 0 1px 3px #999;
}

button.first {
  border-top-left-radius: 5px;
  border-bottom-left-radius: 5px;
}

button.last {
  border-top-right-radius: 5px;
  border-bottom-right-radius: 5px;
}

button.active {
  background-color: rgb(65,102,133);
}

button:hover {
  background-color: steelblue;
}

## index.html
<!DOCTYPE html>
<html>
<head>
    <title>Streamgraph</title>
    <script type="text/javascript" src="http://mbostock.github.com/d3/d3.v2.js?2.8.0"></script>
    <link type="text/css" rel="stylesheet" href="button.css"/>
    <script type="text/javascript" src="stream_layers.js"></script>
    <script type="text/javascript" src="stream-chart.js"></script>
</head>
<body>
<div id="chart">
    <button class="first last" onclick="transition()">
        Update
    </button><p>
</div>
<script>
    var n = 20, // number of layers
        m = 200; // number of samples per layer

    var data1 = stream_layers(n, m);
    var data0 = stream_layers(n, m);
    var colors = d3.range(n).map(function() { return d3.interpolateRgb("#aad", "#556")(Math.random()); });

    var streamgraph = streamgraphChart()
            .margin({top: 10, right: 10, bottom: 10, left: 10})
            .color(function(d, i) { return colors[i]; }) // use same colors for both data sets
            .transitionDuration(1500);

    d3.select("#chart")
            .datum(data0)
            .call(streamgraph);

    function transition() {
        d3.select("#chart")
                .datum(function() {
                    var d = data1;
                    data1 = data0;
                    return data0 = d;
                })
                .call(streamgraph);
    }

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

## stream-chart.js
function streamgraphChart() {
    var margin = {top: 0, right: 0, bottom: 0, left: 0},
        width = 960,
        height = 500,
        transitionDuration = 1000,
        color = function() { return d3.interpolateRgb("#aad", "#556")(Math.random()); };

    var streamgraph =  d3.layout.stack().offset("wiggle");

    function chart(selection) {
        selection.each(function(data) {

            // Compute the streamgraph.
            data = streamgraph(data);

            var mx = data[0].length - 1, // assumes that all layers have same # of samples & that there is at least one layer
                my = d3.max(data, function(d) {
                    return d3.max(d, function(d) {
                        return d.y0 + d.y;
                    });
                });

            // Select the svg element, if it exists.
            var svg = d3.select(this).selectAll("svg").data([data]);

            // Otherwise, create the skeletal chart.
            var gEnter = svg.enter().append("svg").append("g");

            // Update the outer dimensions.
            svg .attr("width", width)
                .attr("height", height);

            // Update the inner dimensions.
            var g = svg.select("g")
                .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

            // Update the streamgraph
            var availableWidth = width - margin.left - margin.right,
                availableHeight = height - margin.top - margin.bottom;

            var area = d3.svg.area()
                .x(function(d) { return d.x * availableWidth / mx; })
                .y0(function(d) { return availableHeight - d.y0 * availableHeight / my; })
                .y1(function(d) { return availableHeight - (d.y + d.y0) * availableHeight / my; });

            var path = g.selectAll("path").data(data);

            path.enter().append("path");
            path.exit().remove();
            path.style("fill", color).transition().duration(transitionDuration).attr("d", area);
        });
    }

    chart.color = function(_) {
        if (!arguments.length) return color;
        color = _;
        return chart;
    };

    chart.transitionDuration = function(_) {
        if (!arguments.length) return transitionDuration;
        transitionDuration = _;
        return chart;
    };

    chart.margin = function(_) {
        if (!arguments.length) return margin;
        margin = _;
        return chart;
    };

    chart.width = function(_) {
        if (!arguments.length) return width;
        width = _;
        return chart;
    };

    chart.height = function(_) {
        if (!arguments.length) return height;
        height = _;
        return chart;
    };

    return chart;
}

## stream_layers.js
/* Inspired by Lee Byron's test data generator. */
function stream_layers(n, m, o) {
  if (arguments.length < 3) o = 0;
  function bump(a) {
    var x = 1 / (.1 + Math.random()),
        y = 2 * Math.random() - .5,
        z = 10 / (.1 + Math.random());
    for (var i = 0; i < m; i++) {
      var w = (i / m - y) * z;
      a[i] += x * Math.exp(-w * w);
    }
  }
  return d3.range(n).map(function() {
      var a = [], i;
      for (i = 0; i < m; i++) a[i] = o + o * Math.random();
      for (i = 0; i < 5; i++) bump(a);
      return a.map(stream_index);
    });
}

function stream_index(d, i) {
  return {x: i, y: Math.max(0, d)};
}
	button {
	font: 14px Helvetica Neue;
	background-color: #222;
	background-image: -moz-linear-gradient(top, rgba(255,255,255,.25), rgba(255,255,255,.11));
	background-image: -webkit-gradient(linear,left top,left bottom,color-stop(0, rgba(255,255,255,.25)),color-stop(1, rgba(255,255,255,.11)));
	background-image: -webkit-linear-gradient(rgba(255,255,255,.25), rgba(255,255,255,.11));
	color: #fff;
	text-rendering: optimizeLegibility;
	text-shadow: 0 -1px 1px #222;
	padding: 6px 10px 6px 10px;
	border: 0;
	border-radius: 0;
	border-bottom: 1px solid #222;
	margin: 0;
	-moz-box-shadow: 0 1px 3px #999;
	-webkit-box-shadow: 0 1px 3px #999;
	}

	button.first {
	border-top-left-radius: 5px;
	border-bottom-left-radius: 5px;
	}

	button.last {
	border-top-right-radius: 5px;
	border-bottom-right-radius: 5px;
	}

	button.active {
	background-color: rgb(65,102,133);
	}

	button:hover {
	background-color: steelblue;
	}
	<!DOCTYPE html>
	<html>
	<head>
	<title>Streamgraph</title>
	<script type="text/javascript" src="http://mbostock.github.com/d3/d3.v2.js?2.8.0"></script>
	<link type="text/css" rel="stylesheet" href="button.css"/>
	<script type="text/javascript" src="stream_layers.js"></script>
	<script type="text/javascript" src="stream-chart.js"></script>
	</head>
	<body>
	<div id="chart">
	<button class="first last" onclick="transition()">
	Update
	</button><p>
	</div>
	<script>
	var n = 20, // number of layers
	m = 200; // number of samples per layer

	var data1 = stream_layers(n, m);
	var data0 = stream_layers(n, m);
	var colors = d3.range(n).map(function() { return d3.interpolateRgb("#aad", "#556")(Math.random()); });

	var streamgraph = streamgraphChart()
	.margin({top: 10, right: 10, bottom: 10, left: 10})
	.color(function(d, i) { return colors[i]; }) // use same colors for both data sets
	.transitionDuration(1500);

	d3.select("#chart")
	.datum(data0)
	.call(streamgraph);

	function transition() {
	d3.select("#chart")
	.datum(function() {
	var d = data1;
	data1 = data0;
	return data0 = d;
	})
	.call(streamgraph);
	}

	</script>
	</body>
	</html>
	function streamgraphChart() {
	var margin = {top: 0, right: 0, bottom: 0, left: 0},
	width = 960,
	height = 500,
	transitionDuration = 1000,
	color = function() { return d3.interpolateRgb("#aad", "#556")(Math.random()); };

	var streamgraph = d3.layout.stack().offset("wiggle");

	function chart(selection) {
	selection.each(function(data) {

	// Compute the streamgraph.
	data = streamgraph(data);

	var mx = data[0].length - 1, // assumes that all layers have same # of samples & that there is at least one layer
	my = d3.max(data, function(d) {
	return d3.max(d, function(d) {
	return d.y0 + d.y;
	});
	});

	// Select the svg element, if it exists.
	var svg = d3.select(this).selectAll("svg").data([data]);

	// Otherwise, create the skeletal chart.
	var gEnter = svg.enter().append("svg").append("g");

	// Update the outer dimensions.
	svg .attr("width", width)
	.attr("height", height);

	// Update the inner dimensions.
	var g = svg.select("g")
	.attr("transform", "translate(" + margin.left + "," + margin.top + ")");

	// Update the streamgraph
	var availableWidth = width - margin.left - margin.right,
	availableHeight = height - margin.top - margin.bottom;

	var area = d3.svg.area()
	.x(function(d) { return d.x * availableWidth / mx; })
	.y0(function(d) { return availableHeight - d.y0 * availableHeight / my; })
	.y1(function(d) { return availableHeight - (d.y + d.y0) * availableHeight / my; });

	var path = g.selectAll("path").data(data);

	path.enter().append("path");
	path.exit().remove();
	path.style("fill", color).transition().duration(transitionDuration).attr("d", area);
	});
	}

	chart.color = function(_) {
	if (!arguments.length) return color;
	color = _;
	return chart;
	};

	chart.transitionDuration = function(_) {
	if (!arguments.length) return transitionDuration;
	transitionDuration = _;
	return chart;
	};

	chart.margin = function(_) {
	if (!arguments.length) return margin;
	margin = _;
	return chart;
	};

	chart.width = function(_) {
	if (!arguments.length) return width;
	width = _;
	return chart;
	};

	chart.height = function(_) {
	if (!arguments.length) return height;
	height = _;
	return chart;
	};

	return chart;
	}
	/* Inspired by Lee Byron's test data generator. */
	function stream_layers(n, m, o) {
	if (arguments.length < 3) o = 0;
	function bump(a) {
	var x = 1 / (.1 + Math.random()),
	y = 2 * Math.random() - .5,
	z = 10 / (.1 + Math.random());
	for (var i = 0; i < m; i++) {
	var w = (i / m - y) * z;
	a[i] += x * Math.exp(-w * w);
	}
	}
	return d3.range(n).map(function() {
	var a = [], i;
	for (i = 0; i < m; i++) a[i] = o + o * Math.random();
	for (i = 0; i < 5; i++) bump(a);
	return a.map(stream_index);
	});
	}

	function stream_index(d, i) {
	return {x: i, y: Math.max(0, d)};
	}