health violations

<!DOCTYPE html>
<meta charset="utf-8">
<style>
.bar {
  fill: steelblue;
}

.bar:hover {
  fill: lightblue;
}

.axis text {
  font: 10px sans-serif;
}

.axis path,
.axis line {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}

.x.axis path {
  display: none;
}

.tooltip {
  position: absolute;
  padding: 10px;
  font: 12px sans-serif;
  background: #222;
  color: #fff;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
  opacity: 0.9;
  visibility: hidden;
}
</style>

/*
Most of this code is reused with other d3 stuff I've played around with.
eg: https://bl.ocks.org/cjhin/0f02bb790279ad89061a1f741fa8507c
The majority of the new code is in lines 61-95 "Data enrichment"
*/

///////////////////////
// Parse the Data
d3.csv("Violations-2012.csv", function(raw_data) {
  ///////////////////////
  // Data enrichment (additional calculations)

// Calculate the violation counts (basically histogram/bin it)
  var temp_obj = {};
  raw_data.forEach(function(d) {
    if(!(d['violation_category'] in temp_obj)) {
      temp_obj[d['violation_category']] = 0;
    }
    temp_obj[d['violation_category']] += 1;
  });

// Do a few more calculations to get the first/last violation dates
  // and then package into an array for d3
  var data = [];
  for(cat in temp_obj) {
    // Take advantage of d3.extent and filter by category to get the dates of the first and last violation
    var dates = d3.extent(raw_data, function(d) {
      if(d['violation_category'] == cat) {
        return d['violation_date'];
      }
    });

data.push({
      violation_category: cat,
      count: temp_obj[cat],
      // It would appear that all the timestamps are 00:00:00, so just save the date
      first_violation: new Date(dates[0]).toLocaleDateString('en-US'),
      last_violation: new Date(dates[1]).toLocaleDateString('en-US')
    });
  };

// sort the bars from highest to lowest count
  data = data.sort(function(a, b) { return b['count'] - a['count']; });

///////////////////////
  // Chart Size Setup
  var margin = { top: 35, right: 0, bottom: 30, left: 40 };

var width = 960 - margin.left - margin.right;
  var height = 500 - margin.top - margin.bottom;

var chart = d3.select(".chart")
      .attr("width", 960)
      .attr("height", 500)
    .append("g")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

///////////////////////
  // Scales
  var x = d3.scale.ordinal()
      .domain(data.map(function(d) { return d['violation_category']; }))
      .rangeRoundBands([0, width], .1);

var y = d3.scale.linear()
      .domain([0, d3.max(data, function(d) { return d['count']; }) * 1.1])
      .range([height, 0]);

///////////////////////
  // Axis
  var xAxis = d3.svg.axis()
      .scale(x)
      .orient("bottom");

var yAxis = d3.svg.axis()
      .scale(y)
      .orient("left");

chart.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);

chart.append("g")
      .attr("class", "y axis")
      .call(yAxis);

///////////////////////
  // Title
  chart.append("text")
    .text('2012 Violations by Count (hover for details)')
    .attr("text-anchor", "middle")
    .attr("class", "graph-title")
    .attr("y", -10)
    .attr("x", width / 2.0);

///////////////////////
  // Bars
  var bar = chart.selectAll(".bar")
      .data(data)
    .enter().append("rect")
      .attr("class", "bar")
      .attr("x", function(d) { return x(d['violation_category']); })
      .attr("y", height)
      .attr("width", x.rangeBand())
      .attr("height", 0);

bar.transition()
      .duration(1500)
      .ease("elastic")
      .attr("y", function(d) { return y(d['count']); })
      .attr("height", function(d) { return height - y(d['count']); })

///////////////////////
  // Tooltips
  var tooltip = d3.select("body").append("div")
      .attr("class", "tooltip");

bar.on("mouseover", function(d) {
        tooltip.html("Count: " + d['count'] + "<br/>" +
            "First Violation: " + d.first_violation + "<br/>" +
            "Last Violation: " + d.last_violation
            )
            .style("visibility", "visible");
      })
      .on("mousemove", function(d) {
        tooltip.style("top", event.pageY - (tooltip[0][0].clientHeight + 5) + "px")
            .style("left", event.pageX - (tooltip[0][0].clientWidth / 2.0) + "px");
      })
      .on("mouseout", function(d) {
        tooltip.style("visibility", "hidden");
      });
});
</script>

https://d3js.org/d3.v3.min.js