bike_collisions.js

var m = [19, 20, 20, 19], // top right bottom left margin
    w = 960 - m[1] - m[3], // width
    h = 136 - m[0] - m[2], // height
    z = 17; // cell size

var day = d3.time.format("%w"),
    week = d3.time.format("%U"),
    percent = d3.format(".1"),
    format = d3.time.format("%Y-%m-%d");

var color = d3.scale.quantize()
    .domain([6, 0])
    .range(d3.range(6));

var svg = d3.select("#chart").selectAll("svg")
    .data(d3.range(2002, 2011))
  .enter().append("svg")
    .attr("width", w + m[1] + m[3])
    .attr("height", h + m[0] + m[2])
    .attr("class", "RdYlGn")
  .append("g")
    .attr("transform", "translate(" + (m[3] + (w - z * 53) / 2) + "," + (m[0] + (h - z * 7) / 2) + ")");

svg.append("text")
    .attr("transform", "translate(-6," + z * 3.5 + ")rotate(-90)")
    .attr("text-anchor", "middle")
    .text(String);

var rect = svg.selectAll("rect.day")
    .data(function(d) { return d3.time.days(new Date(d, 0, 1), new Date(d + 1, 0, 1)); })
  .enter().append("rect")
    .attr("class", "day")
    .attr("width", z)
    .attr("height", z)
    .attr("x", function(d) { return week(d) * z; })
    .attr("y", function(d) { return day(d) * z; })
    .datum(format);

rect.append("title")
    .text(function(d) { return d; });

svg.selectAll("path.month")
    .data(function(d) { return d3.time.months(new Date(d, 0, 1), new Date(d + 1, 0, 1)); })
  .enter().append("path")
    .attr("class", "month")
    .attr("d", monthPath);

d3.csv("./data/bike_collisions.csv", function(csv) {
  var data = d3.nest()
    .key(function(d) { return d.ACCDATE; })
    .rollup(function(d) { return sumIncidents(d) })
    .map(csv);

  rect.filter(function(d) { return d in data; })
      .attr("class", function(d) { return "day q" + color(data[d]) + "-6"; })
    .select("title")
      .text(function(d) { return d + ": " + data[d]; });
});

function monthPath(t0) {
  var t1 = new Date(t0.getFullYear(), t0.getMonth() + 1, 0),
      d0 = +day(t0), w0 = +week(t0),
      d1 = +day(t1), w1 = +week(t1);
  return "M" + (w0 + 1) * z + "," + d0 * z
      + "H" + w0 * z + "V" + 7 * z
      + "H" + w1 * z + "V" + (d1 + 1) * z
      + "H" + (w1 + 1) * z + "V" + 0
      + "H" + (w0 + 1) * z + "Z";
}

function sumIncidents(data) {
    var s = 0;
    for (i=0;i<data.length;i++) {
        s += 1;
    }
    return s;
}