1 var n = 20, // number of layers

     2     m = 200, // number of samples per layer

     3     data0 = d3.layout.stack().offset("wiggle")(stream_layers(n, m)),

     4     data1 = d3.layout.stack().offset("wiggle")(stream_layers(n, m)),

     5     color = d3.interpolateRgb("#aad", "#556");

     6 

     7 var w = 960,

     8     h = 500,

     9     mx = m - 1,

    10     my = d3.max(data0.concat(data1), function(d) {

    11       return d3.max(d, function(d) {

    12         return d.y0 + d.y;

    13       });

    14     });

    15 

    16 var area = d3.svg.area()

    17     .x(function(d) { return d.x * w / mx; })

    18     .y0(function(d) { return h - d.y0 * h / my; })

    19     .y1(function(d) { return h - (d.y + d.y0) * h / my; });

    20 

    21 var vis = d3.select("#chart")

    22   .append("svg:svg")

    23     .attr("width", w)

    24     .attr("height", h);

    25 

    26 vis.selectAll("path")

    27     .data(data0)

    28   .enter().append("svg:path")

    29     .style("fill", function() { return color(Math.random()); })

    30     .attr("d", area);

    31 

    32 function transition() {

    33   d3.selectAll("path")

    34       .data(function() {

    35         var d = data1;

    36         data1 = data0;

    37         return data0 = d;

    38       })

    39     .transition()

    40       .duration(2500)

    41       .attr("d", area);

    42 }