Day / Hour Heatmap

Inspired by Trulia Trends - but with code and using SVG.

Example data shows concurrent user sessions over time, taken from a development environment.

MIT Licensed, see LICENSE.MD.

<!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.v3.js"></script>
  </head>
  <body>
    <div id="chart"></div>
    <div id="dataset-picker">
    </div>
    <script type="text/javascript">
      var 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", "12p", "1p", "2p", "3p", "4p", "5p", "6p", "7p", "8p", "9p", "10p", "11p", "12a"];
          datasets = ["data.tsv", "data2.tsv"];

var 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 + ")");

var cards = svg.selectAll(".hour")
              .data(data, function(d) {return d.day+':'+d.hour;});

cards.append("title");

cards.enter().append("rect")
              .attr("x", function(d) { return (d.hour - 1) * gridSize; })
              .attr("y", function(d) { return (d.day - 1) * gridSize; })
              .attr("rx", 4)
              .attr("ry", 4)
              .attr("class", "hour bordered")
              .attr("width", gridSize)
              .attr("height", gridSize)
              .style("fill", colors[0]);

cards.transition().duration(1000)
              .style("fill", function(d) { return colorScale(d.value); });

cards.select("title").text(function(d) { return d.value; });
          
          cards.exit().remove();

var legend = svg.selectAll(".legend")
              .data([0].concat(colorScale.quantiles()), function(d) { return d; });

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

legend.append("rect")
            .attr("x", function(d, i) { return legendElementWidth * i; })
            .attr("y", height)
            .attr("width", legendElementWidth)
            .attr("height", gridSize / 2)
            .style("fill", function(d, i) { return colors[i]; });

legend.append("text")
            .attr("class", "mono")
            .text(function(d) { return "≥ " + Math.round(d); })
            .attr("x", function(d, i) { return legendElementWidth * i; })
            .attr("y", height + gridSize);

legend.exit().remove();

});  
      };

heatmapChart(datasets[0]);
      
      var datasetpicker = d3.select("#dataset-picker").selectAll(".dataset-button")
        .data(datasets);

datasetpicker.enter()
        .append("input")
        .attr("value", function(d){ return "Dataset " + d })
        .attr("type", "button")
        .attr("class", "dataset-button")
        .on("click", function(d) {
          heatmapChart(d);
        });
    </script>
  </body>
</html>

Modified http://d3js.org/d3.v3.js to a secure url

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