// Based on http://bl.ocks.org/900762 by John Firebaugh

d3.json("../data/faithful.json", function(faithful) {

  data = faithful;

  var w = 800,

      h = 400,

      x = d3.scale.linear().domain([30, 110]).range([0, w]);

      bins = d3.layout.histogram().frequency(false).bins(x.ticks(60))(data),

      max = d3.max(bins, function(d) { return d.y; }),

      y = d3.scale.linear().domain([0, .1]).range([0, h]),

      kde = science.stats.kde().sample(data);

  var vis = d3.select("body")

    .append("svg:svg")

      .attr("width", w)

      .attr("height", h);

  var bars = vis.selectAll("g.bar")

      .data(bins)

    .enter().append("svg:g")

      .attr("class", "bar")

      .attr("transform", function(d, i) {

        return "translate(" + x(d.x) + "," + (h - y(d.y)) + ")";

      });

  bars.append("svg:rect")

      .attr("fill", "steelblue")

      .attr("width", function(d) { return x(d.dx + 30) - 1; })

      .attr("height", function(d) { return y(d.y); });

  var line = d3.svg.line()

      .x(function(d) { return x(d[0]); })

      .y(function(d) { return h - y(d[1]); });

  vis.selectAll("path")

      .data(d3.values(science.stats.bandwidth))

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

      .attr("d", function(h) {

        return line(kde.bandwidth(h)(d3.range(30, 110, .1)));

      });

});