I've been working on creating a d3.js heatmap chart, and I've encountered an issue with the colors. Initially, I used code from this link and then modified it to read data from a PHP file that outputs JSON format data. However, after making these modifications, the heatmap is displaying all grids in black color with some white spaces between them.
I am relatively new to d3 charts, so please forgive any minor mistakes you may come across in the code snippet below:
<!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="http://d3js.org/d3.v3.js"></script>
</head>
<body>
<div id="chart"></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", "12a", "1p", "2p", "3p", "4p", "5p", "6p", "7p", "8p", "9p", "10p", "11p", "12p"];
// datasets = ["data1.tsv", "data2.tsv"];
d3.json("heatmaptry2.php", function(error, data) {
data.forEach(function(d) {
console.log(d);
day= +d.day;
hour= +d.hour;
value= +d.value;
});
var colorScale = d3.scale.quantile();
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 dayLabels = svg.selectAll(".dayLabel")
.data(days)
.enter().append("text")
.text(function (d) { return d; })
.attr("x", 0)
.attr("y", function (d, i) { return i * gridSize; })
.style("text-anchor", "end")
.attr("transform", "translate(-5," + gridSize / 1.5 + ")")
.attr("class", function (d, i) { return ((i >= 0 && i <= 4) ? "dayLabel mono axis axis-workweek" : "dayLabel mono axis"); });
var timeLabels = svg.selectAll(".timeLabel")
.data(times)
.enter().append("text")
.text(function(d) { return d; })
.attr("x", function(d, i) { return i * gridSize; })
.attr("y", 0)
.style("text-anchor", "middle")
.attr("transform", "translate(" + gridSize / 2 + ", -5)")
.attr("class", function(d, i) { return ((i >= 7 && i <= 16) ? "timeLabel mono axis axis-worktime" : "timeLabel mono axis"); });
var heatMap = svg.selectAll(".hour")
.data(data)
.enter().append("rect")
.attr("x", function(d) { return (d.hour) * gridSize; })
.attr("y", function(d) { return (d.day ) * gridSize; })
.attr("rx", 4)
.attr("ry", 4)
.attr("class", "hour bordered")
.attr("width", gridSize)
.attr("height", gridSize)
.style("fill", colors[0]);
heatMap.transition().duration(1000)
.style("fill", function(d) { return colorScale(d.value); });
heatMap.append("title").text(function(d) { return d.value; });
heatMap.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();
});
</script>
</body>
</html>