Commit | Line | Data |
---|---|---|
54425b14 | 1 | <!DOCTYPE html> |
05a1d116 DV |
2 | <html> |
3 | <head> | |
fd6b8dad | 4 | <link rel="stylesheet" href="../dist/dygraph.css"> |
05a1d116 | 5 | <title>Linear Regression</title> |
fbd6834a | 6 | <script type="text/javascript" src="../dist/dygraph.js"></script> |
7e5ddc94 | 7 | |
05a1d116 DV |
8 | <style type="text/css"> |
9 | body { max-width: 640 px; } | |
10 | </style> | |
11 | </head> | |
12 | <body> | |
13 | <h2>Linear Regression Demo</h2> | |
14 | <p>Click the buttons to generate linear regressions over either data | |
15 | series. If you zoom in and click the regression button, the regression will | |
16 | only be run over visible points. Zoom back out to see what the local | |
17 | regression looks like over the full data.</p> | |
18 | ||
19 | <div id="demodiv" style="width: 480px; height: 320px;"></div> | |
20 | ||
21 | <script type="text/javascript"> | |
176c94a4 | 22 | var data = []; |
05a1d116 | 23 | for (var i = 0; i < 120; i++) { |
176c94a4 DV |
24 | data.push([i, |
25 | i / 5.0 + 10.0 * Math.sin(i / 3.0), | |
26 | 30.0 - i / 5.0 - 10.0 * Math.sin(i / 3.0 + 1.0)]); | |
05a1d116 DV |
27 | } |
28 | ||
29 | g = new Dygraph( | |
30 | document.getElementById("demodiv"), | |
31 | data, | |
32 | { | |
176c94a4 | 33 | labels: ['X', 'Y1', 'Y2'], |
05a1d116 | 34 | underlayCallback: drawLines, |
de0445fc | 35 | drawPoints: true, |
176c94a4 | 36 | strokeWidth: 0.0 |
05a1d116 DV |
37 | } |
38 | ); | |
39 | ||
40 | // coefficients of regression for each series. | |
41 | // if coeffs = [ null, [1, 2], null ] then we draw a regression for series 1 | |
42 | // only. The regression line is y = 1 + 2 * x. | |
43 | var coeffs = [ null, null, null ]; | |
44 | function regression(series) { | |
45 | // Only run the regression over visible points. | |
46 | var range = g.xAxisRange(); | |
47 | ||
48 | var sum_xy = 0.0, sum_x = 0.0, sum_y = 0.0, sum_x2 = 0.0, num = 0; | |
49 | for (var i = 0; i < g.numRows(); i++) { | |
50 | var x = g.getValue(i, 0); | |
51 | if (x < range[0] || x > range[1]) continue; | |
52 | ||
53 | var y = g.getValue(i, series); | |
54 | if (y == null) continue; | |
c5a37449 DV |
55 | if (y.length == 2) { |
56 | // using fractions | |
57 | y = y[0] / y[1]; | |
58 | } | |
05a1d116 DV |
59 | |
60 | num++; | |
61 | sum_x += x; | |
62 | sum_y += y; | |
63 | sum_xy += x * y; | |
64 | sum_x2 += x * x; | |
65 | } | |
66 | ||
67 | var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num); | |
68 | var b = (sum_y - a * sum_x) / num; | |
69 | ||
70 | coeffs[series] = [b, a]; | |
4df1af70 | 71 | if (typeof(console) != 'undefined') { |
2a07b0ad DV |
72 | console.log("coeffs(" + series + "): [" + b + ", " + a + "]"); |
73 | } | |
05a1d116 DV |
74 | |
75 | g.updateOptions({}); // forces a redraw. | |
76 | } | |
77 | ||
78 | function clearLines() { | |
79 | for (var i = 0; i < coeffs.length; i++) coeffs[i] = null; | |
80 | g.updateOptions({}); | |
81 | } | |
82 | ||
0a171c09 DV |
83 | function toHex(rgb) { |
84 | return 'rgb(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ')'; | |
85 | } | |
86 | ||
05a1d116 DV |
87 | function drawLines(ctx, area, layout) { |
88 | if (typeof(g) == 'undefined') return; // won't be set on the initial draw. | |
89 | ||
90 | var range = g.xAxisRange(); | |
91 | for (var i = 0; i < coeffs.length; i++) { | |
92 | if (!coeffs[i]) continue; | |
93 | var a = coeffs[i][1]; | |
94 | var b = coeffs[i][0]; | |
95 | ||
96 | var x1 = range[0]; | |
97 | var y1 = a * x1 + b; | |
98 | var x2 = range[1]; | |
99 | var y2 = a * x2 + b; | |
100 | ||
101 | var p1 = g.toDomCoords(x1, y1); | |
102 | var p2 = g.toDomCoords(x2, y2); | |
103 | ||
0a171c09 | 104 | var c = Dygraph.toRGB_(g.getColors()[i - 1]); |
34bbe78b DV |
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)); | |
0a171c09 | 108 | var color = toHex(c); |
05a1d116 DV |
109 | ctx.save(); |
110 | ctx.strokeStyle = color; | |
111 | ctx.lineWidth = 1.0; | |
112 | ctx.beginPath(); | |
113 | ctx.moveTo(p1[0], p1[1]); | |
114 | ctx.lineTo(p2[0], p2[1]); | |
115 | ctx.closePath(); | |
116 | ctx.stroke(); | |
117 | ctx.restore(); | |
118 | } | |
119 | } | |
120 | ||
121 | </script> | |
122 | ||
123 | <div style="position: absolute; left: 500px; top: 150px;"> | |
124 | <input type=button style="color: green;" value="Regression (Y1)" onClick="regression(1)" /> | |
125 | <br/><br/> | |
126 | <input type=button style="color: blue;" value="Regression (Y2)" onClick="regression(2)" /> | |
127 | <br/><br/> | |
128 | <input type=button value="Clear Lines" onClick="clearLines()" /> | |
129 | </div> | |
130 | </body> | |
131 | </html> |