Histogram II

Source: City of Chicago.

This histogram shows the number of homicides in Chicago for each week in 2015.

<!DOCTYPE html>
<meta charset="utf-8">
<style>

.bar rect {
  fill: steelblue;
}

.bar text {
  fill: #fff;
  font: 10px sans-serif;
}

</style>
<body>
<script src="//d3js.org/d3.v4.min.js"></script>
<script>

var parseDate = d3.timeParse("%m/%d/%Y %H:%M:%S %p"),
    formatCount = d3.format(",.0f");

var margin = {top: 10, right: 30, bottom: 30, left: 30},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var x = d3.scaleTime()
    .domain([new Date(2015, 0, 1), new Date(2016, 0, 1)])
    .rangeRound([0, width]);

var y = d3.scaleLinear()
    .range([height, 0]);

var histogram = d3.histogram()
    .value(function(d) { return d.date; })
    .domain(x.domain())
    .thresholds(x.ticks(d3.timeWeek));

var svg = d3.select("body").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

svg.append("g")
    .attr("class", "axis axis--x")
    .attr("transform", "translate(0," + height + ")")
    .call(d3.axisBottom(x));

d3.csv("homicides.csv", type, function(error, data) {
  if (error) throw error;

var bins = histogram(data);

y.domain([0, d3.max(bins, function(d) { return d.length; })]);

var bar = svg.selectAll(".bar")
      .data(bins)
    .enter().append("g")
      .attr("class", "bar")
      .attr("transform", function(d) { return "translate(" + x(d.x0) + "," + y(d.length) + ")"; });

bar.append("rect")
      .attr("x", 1)
      .attr("width", function(d) { return x(d.x1) - x(d.x0) - 1; })
      .attr("height", function(d) { return height - y(d.length); });

bar.append("text")
      .attr("dy", ".75em")
      .attr("y", 6)
      .attr("x", function(d) { return (x(d.x1) - x(d.x0)) / 2; })
      .attr("text-anchor", "middle")
      .text(function(d) { return formatCount(d.length); });
});

function type(d) {
  d.date = parseDate(d.date);
  return d;
}

</script>

https://d3js.org/d3.v4.min.js