«
»

Simple basic heatmap in D3.JS

December 5, 2014, 9:51 pm

heatmap

The code below creates the extremely basic heatmap shown above using D3.JS. The heatmap data is stored in a flat 1D array, so X and Y dimensions need to be provided. I don’t think it would be too hard to modify this to process 2D arrays.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
<html>
<body>
<svg class="output" width="500" height="500">
</svg>
 
<script src="http://d3js.org/d3.v3.min.js"></script>
<script>
 
var max_value = 9;
 
// This function converts a 0->max_value number to a rgb string for the heatmap
function get_rgb(d) {
  var ratio = 2 * (d/max_value)
  var r = Math.floor(Math.max(0, 255*(ratio - 1)))
  var b = Math.floor(Math.max(0, 255*(1 - ratio)))
  var g = 255 - b - r
   
  return "rgb(" + r + "," + g + "," + b + ")";
}
 
var svg = d3.select(".output")
 
var mydata = [
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,1,1,1,1,1,1,1,0,0,0,0,0,0,0, 0,0,0,0,0,0,1,1,1,1,1,1,1,0,0,0,0,0,0,0,
   0,0,0,0,1,1,1,2,2,2,2,2,1,1,1,0,0,0,0,0, 0,0,0,0,1,1,1,2,2,2,2,2,1,1,1,0,0,0,0,0,
   0,0,0,1,1,2,2,3,3,3,3,3,2,2,1,1,0,0,0,0, 0,0,0,1,1,2,2,3,3,3,3,3,2,2,1,1,0,0,0,0,
   0,0,1,1,2,3,3,3,4,4,4,3,3,3,2,1,1,0,0,0, 0,0,1,1,2,3,3,3,4,4,4,3,3,3,2,1,1,0,0,0,
   0,0,1,1,2,3,4,4,4,5,4,4,4,3,2,2,1,0,0,0, 0,0,1,1,2,3,4,4,4,5,4,4,4,3,2,2,1,0,0,0,
   0,1,1,2,3,3,4,5,5,6,5,5,4,4,3,3,2,1,0,0, 0,1,1,2,3,3,4,5,5,6,5,5,4,4,3,3,2,1,0,0,
   0,1,2,2,3,4,4,5,6,7,6,5,5,4,4,3,2,1,0,0, 0,1,2,2,3,4,4,5,6,7,6,5,5,4,4,3,2,1,0,0,
   0,1,2,3,3,4,5,5,6,8,7,6,5,5,4,3,2,1,0,0, 0,1,2,3,3,4,5,5,6,8,8,6,5,5,4,3,2,1,0,0,
   0,1,2,3,4,4,5,6,6,7,7,6,5,5,4,3,2,1,0,0, 0,1,2,3,4,4,5,6,6,7,6,6,5,5,4,3,2,1,0,0,
   0,1,2,3,4,4,5,5,6,6,6,5,5,4,4,3,2,1,0,0, 0,1,2,3,4,4,5,5,6,6,6,6,5,4,4,3,2,1,0,0,
   0,1,2,3,3,4,4,5,5,6,5,5,4,4,3,3,2,1,0,0, 0,1,2,3,3,4,4,5,5,6,5,5,5,4,3,3,2,1,0,0,
   0,1,1,2,3,3,4,4,5,5,5,4,4,4,3,2,1,1,0,0, 0,1,1,2,3,3,4,4,5,5,5,4,4,4,3,2,1,1,0,0,
   0,0,1,1,2,3,3,4,4,4,4,4,3,3,3,2,1,0,0,0, 0,0,1,1,2,3,3,4,4,4,4,4,3,3,3,2,1,0,0,0,
   0,0,1,1,2,2,3,3,3,4,4,3,3,2,2,1,1,0,0,0, 0,0,1,1,2,2,3,3,3,4,4,3,3,2,2,1,1,0,0,0,
   0,0,0,1,1,2,2,2,3,3,3,2,2,2,1,1,0,0,0,0, 0,0,0,1,1,2,2,2,3,3,3,2,2,2,1,1,0,0,0,0,
   0,0,0,0,1,1,1,2,2,2,2,2,1,1,1,0,0,0,0,0, 0,0,0,0,1,1,1,2,2,2,2,2,1,1,1,0,0,0,0,0,
   0,0,0,0,0,0,1,1,1,1,1,1,1,0,0,0,0,0,0,0, 0,0,0,0,0,0,1,1,1,1,1,1,1,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,1,1,1,1,1,1,1,0,0,0,0,0,0,0, 0,0,0,0,0,0,1,1,1,1,1,1,1,0,0,0,0,0,0,0,
   0,0,0,0,1,1,1,2,2,2,2,2,1,1,1,0,0,0,0,0, 0,0,0,0,1,1,1,2,2,2,2,2,1,1,1,0,0,0,0,0,
   0,0,0,1,1,2,2,3,3,3,3,3,2,2,1,1,0,0,0,0, 0,0,0,1,1,2,2,3,3,3,3,3,2,2,1,1,0,0,0,0,
   0,0,1,1,2,3,3,3,4,4,4,3,3,3,2,1,1,0,0,0, 0,0,1,1,2,3,3,3,4,4,4,3,3,3,2,1,1,0,0,0,
   0,0,1,1,2,3,4,4,4,5,4,4,4,3,2,2,1,0,0,0, 0,0,1,1,2,3,4,4,4,5,4,4,4,3,2,2,1,0,0,0,
   0,1,1,2,3,3,4,5,5,6,5,5,4,4,3,3,2,1,0,0, 0,1,1,2,3,3,4,5,5,6,5,5,4,4,3,3,2,1,0,0,
   0,1,2,2,3,4,4,5,6,7,6,5,5,4,4,3,2,1,0,0, 0,1,2,2,3,4,4,5,6,7,6,5,5,4,4,3,2,1,0,0,
   0,1,2,3,3,4,5,5,7,8,7,6,5,5,4,3,2,1,0,0, 0,1,2,3,3,4,5,5,7,8,8,6,5,5,4,3,2,1,0,0,
   0,1,2,3,4,4,5,6,6,7,7,6,5,5,4,3,2,1,0,0, 0,1,2,3,4,4,5,6,6,7,6,6,5,5,4,3,2,1,0,0,
   0,1,2,3,4,4,5,5,6,6,6,6,5,4,4,3,2,1,0,0, 0,1,2,3,4,4,5,5,6,6,6,5,5,4,4,3,2,1,0,0,
   0,1,2,3,3,4,4,5,5,6,5,5,4,4,3,3,2,1,0,0, 0,1,2,3,3,4,4,5,5,6,5,5,4,4,3,3,2,1,0,0,
   0,1,1,2,3,3,4,4,5,5,5,4,4,4,3,2,1,1,0,0, 0,1,1,2,3,3,4,4,5,5,5,4,4,4,3,2,1,1,0,0,
   0,0,1,1,2,3,3,4,4,4,4,4,3,3,3,2,1,0,0,0, 0,0,1,1,2,3,3,4,4,4,4,4,3,3,3,2,1,0,0,0,
   0,0,1,1,2,2,3,3,3,4,4,3,3,2,2,1,1,0,0,0, 0,0,1,1,2,2,3,3,3,4,4,3,3,2,2,1,1,0,0,0,
   0,0,0,1,1,2,2,2,3,3,3,2,2,2,1,1,0,0,0,0, 0,0,0,1,1,2,2,2,3,3,3,2,2,2,1,1,0,0,0,0,
   0,0,0,0,1,1,1,2,2,2,2,2,1,1,1,0,0,0,0,0, 0,0,0,0,1,1,1,2,2,2,2,2,1,1,1,0,0,0,0,0,
   0,0,0,0,0,0,1,1,1,1,1,1,1,0,0,0,0,0,0,0, 0,0,0,0,0,0,1,1,1,1,1,1,1,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
 
]
 
 
var selection = svg.selectAll("rect")
  .data(mydata)
 
var cellsize = 5;
 
var x_dim = 40;
var y_dim = 40;
 
selection.enter().append("rect")
  .attr("x", function(d,i) { return (i%x_dim)*cellsize; })
  .attr("y", function(d,i) { return (Math.floor(i/x_dim))*cellsize; })
  .attr("width", cellsize)
  .attr("height", cellsize)
  .style("fill", function(d) {return get_rgb(d);})
 
</script>
</body>
</html>
Category: Uncategorized

Comments are closed.