4 <link rel=
"stylesheet" href=
"../css/dygraph.css">
5 <title>Linear Regression
</title>
7 For production (minified) code, use:
8 <script type=
"text/javascript" src=
"dygraph-combined.js"></script>
10 <script type=
"text/javascript" src=
"../dist/dygraph.js"></script>
12 <style type=
"text/css">
13 body { max-width:
640 px; }
17 <h2>Linear Regression Demo
</h2>
18 <p>Click the buttons to generate linear regressions over either data
19 series. If you zoom in and click the regression button, the regression will
20 only be run over visible points. Zoom back out to see what the local
21 regression looks like over the full data.
</p>
23 <div id=
"demodiv" style=
"width: 480px; height: 320px;"></div>
25 <script type=
"text/javascript">
27 for (var i =
0; i <
120; i++) {
29 i /
5.0 +
10.0 * Math.sin(i /
3.0),
30 30.0 - i /
5.0 -
10.0 * Math.sin(i /
3.0 +
1.0)]);
32 var labels = ['X', 'Y1', 'Y2'];
36 document.getElementById(
"demodiv"),
42 drawCallback: function(g, is_initial) {
43 if (!is_initial) return;
44 var c = g.getColors();
45 for (var i =
0; i < c.length; i++) orig_colors.push(c[i]);
50 // coefficients of regression for each series.
51 // if coeffs = [ null, [
1,
2], null ] then we draw a regression for series
1
52 // only. The regression line is y =
1 +
2 * x.
53 var coeffs = [ null, null, null ];
54 function regression(series) {
55 // Only run the regression over visible points.
56 var range = g.xAxisRange();
58 var sum_xy =
0.0, sum_x =
0.0, sum_y =
0.0, sum_x2 =
0.0, num =
0;
59 for (var i =
0; i < data.length; i++) {
61 if (x < range[
0] || x
> range[
1]) continue;
63 var y = data[i][series];
64 if (y == null) continue;
77 var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num);
78 var b = (sum_y - a * sum_x) / num;
80 coeffs[series] = [b, a];
81 if (typeof(console) != 'undefined') {
82 console.log(
"coeffs(" + series +
"): [" + b +
", " + a +
"]");
89 return 'rgb(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ')';
92 function updateChart() {
93 // Generate a new data set with the regression lines.
97 for (var i =
0; i < labels.length; i++) {
98 new_labels.push(labels[i]);
99 if (i) new_colors.push(orig_colors[i -
1]);
101 // Darken the series by
50% to generate its regression.
102 var label = labels[i] +
" Regression";
103 new_labels.push(label);
104 var c = Dygraph.toRGB_(orig_colors[i -
1]);
105 c.r = Math.floor(
255 -
0.5 * (
255 - c.r));
106 c.g = Math.floor(
255 -
0.5 * (
255 - c.g));
107 c.b = Math.floor(
255 -
0.5 * (
255 - c.b));
108 new_colors.push(toHex(c));
117 for (var i =
0; i < data.length; i++) {
119 for (var j =
0; j < data[i].length; j++) {
120 new_data[i].push(data[i][j]);
122 new_data[i].push(coeffs[j][
0] + coeffs[j][
1] * data[i][
0]);
127 new_opts.file = new_data;
128 new_opts.labels = new_labels;
129 new_opts.colors = new_colors;
130 g.updateOptions(new_opts);
133 function clearLines() {
134 for (var i =
0; i < coeffs.length; i++) coeffs[i] = null;
140 <div style=
"position: absolute; left: 500px; top: 150px;">
141 <input type=button
style=
"color: green;" value=
"Regression (Y1)" onClick=
"regression(1)" />
143 <input type=button
style=
"color: blue;" value=
"Regression (Y2)" onClick=
"regression(2)" />
145 <input type=button
value=
"Clear Lines" onClick=
"clearLines()" />