Heatmapv4

<!DOCTYPE html>
<meta charset="utf-8">
<html>
  <head>
    <style>
      rect.bordered {
        stroke: #E6E6E6;
        stroke-width:2px;
      }

text.mono {
        font-size: 9pt;
        font-family: Consolas, courier;
        fill: #aaa;
      }

text.axis-workweek {
        fill: #000;
      }

text.axis-worktime {
        fill: #000;
      }
    </style>
    <script src="https://d3js.org/d3.v4.js"></script>
  </head>
  <body>
    <div id="chart"></div>
    <script type="text/javascript">
      const margin = { top: 50, right: 0, bottom: 100, left: 30 },
          width = 960 - margin.left - margin.right,
          height = 430 - margin.top - margin.bottom,
          gridSize = Math.floor(width / 24),
          legendElementWidth = gridSize*2,
          buckets = 9,
          colors = ["#ffffd9","#edf8b1","#c7e9b4","#7fcdbb","#41b6c4","#1d91c0","#225ea8","#253494","#081d58"], // alternatively colorbrewer.YlGnBu[9]
          days = ["Mo", "Tu", "We", "Th", "Fr", "Sa", "Su"],
          times = ["1a", "2a", "3a", "4a", "5a", "6a", "7a", "8a", "9a", "10a", "11a", "12a", "1p", "2p", "3p", "4p", "5p", "6p", "7p", "8p", "9p", "10p", "11p", "12p"];
      		types = ["CHIEF", "ENGINE", "MEDIC", "PRIVATE", "RESCUE CAPTAIN", "RESCUE SQUAD", "SUPPORT", "TRUCK"];
          datasets = ["data1.csv"];

const svg = d3.select("#chart").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 + ")");

const dayLabels = svg.selectAll(".dayLabel")
          .data(days)
          .enter().append("text")
            .text(function (d) { return d; })
            .attr("x", 0)
            .attr("y", (d, i) => i * gridSize)
            .style("text-anchor", "end")
            .attr("transform", "translate(-6," + gridSize / 1.5 + ")")
            .attr("class", (d, i) => ((i >= 0 && i <= 4) ? "dayLabel mono axis axis-workweek" : "dayLabel mono axis"));

const timeLabels = svg.selectAll(".timeLabel")
          .data(times)
          .enter().append("text")
            .text((d) => d)
            .attr("x", (d, i) => i * gridSize*3+15)
            .attr("y", 0)
      			.attr("transform", "rotate(270)")
            .style("text-anchor", "end")
            .attr("transform", "translate(" + gridSize / 2 + ", -6)")
            .attr("class", (d, i) => ((i >= 7 && i <= 16) ? "timeLabel mono axis axis-worktime" : "timeLabel mono axis"));

const type = (d) => {
        return {
          district: d.Neighborhood_District, //hour
          type: d.Unit_Type, //value
          Number_of_Alarms: +d.Number_of_Alarms //day
        };
      };

const heatmapChart = function(tsvFile) {
        d3.csv(tsvFile, type, (error, data) => {
          const colorScale = d3.scaleQuantile()
            .domain([0, buckets - 1, d3.max(data, (d) => d.Number_of_Alarms)])
            .range(colors);

const cards = svg.selectAll(".hour")
              .data(data, (d) => d.day+':'+d.hour);

cards.append("title");

cards.enter().append("rect")
              .attr("x", (d) => (d.hour - 1) * gridSize)
              .attr("y", (d) => (d.day - 1) * gridSize)
              .attr("rx", 4)
              .attr("ry", 4)
              .attr("class", "hour bordered")
              .attr("width", gridSize)
              .attr("height", gridSize)
              .style("fill", colors[0])
            .merge(cards)
              .transition()
              .duration(1000)
              .style("fill", (d) => colorScale(d.day));

cards.select("title").text((d) => d.day);

cards.exit().remove();

const legend = svg.selectAll(".legend")
              .data([0].concat(colorScale.quantiles()), (d) => d);

const legend_g = legend.enter().append("g")
              .attr("class", "legend");

legend_g.append("rect")
            .attr("x", (d, i) => legendElementWidth * i)
            .attr("y", height)
            .attr("width", legendElementWidth)
            .attr("height", gridSize / 2)
            .style("fill", (d, i) => colors[i]);

legend_g.append("text")
            .attr("class", "mono")
            .text((d) => "≥ " + Math.round(d))
            .attr("x", (d, i) => legendElementWidth * i)
            .attr("y", height + gridSize);

legend.exit().remove();
        });
      };

heatmapChart(datasets[0]);
    </script>
  </body>
</html>

Modified http://d3js.org/d3.v4.js to a secure url

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