Commit | Line | Data |
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54425b14 | 1 | <!DOCTYPE html> |
d1dfab80 DV |
2 | <html> |
3 | <head> | |
fd6b8dad | 4 | <link rel="stylesheet" href="../dist/dygraph.css"> |
d1dfab80 | 5 | <title>Linear Regression</title> |
fbd6834a | 6 | <script type="text/javascript" src="../dist/dygraph.js"></script> |
7e5ddc94 | 7 | |
d1dfab80 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"> | |
22 | var data = "X,Y1,Y2\n"; | |
23 | for (var i = 0; i < 120; i++) { | |
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)]); | |
27 | data += i + "," + i + "/120," + (i*(120-i)) + "/" + (60*60) + "\n"; | |
28 | } | |
29 | ||
30 | g = new Dygraph( | |
31 | document.getElementById("demodiv"), | |
32 | data, | |
33 | { | |
34 | underlayCallback: drawLines, | |
35 | drawPoints: true, | |
36 | strokeWidth: 0.0, | |
37 | fractions: true, | |
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38 | errorBars: true, |
39 | pointSize: 1 | |
d1dfab80 DV |
40 | } |
41 | ); | |
42 | ||
43 | // coefficients of regression for each series. | |
44 | // if coeffs = [ null, [1, 2], null ] then we draw a regression for series 1 | |
45 | // only. The regression line is y = 1 + 2 * x. | |
46 | var coeffs = [ null, null, null ]; | |
47 | function regression(series) { | |
48 | // Only run the regression over visible points. | |
49 | var range = g.xAxisRange(); | |
50 | ||
51 | var sum_xy = 0.0, sum_x = 0.0, sum_y = 0.0, sum_x2 = 0.0, num = 0; | |
52 | for (var i = 0; i < g.numRows(); i++) { | |
53 | var x = g.getValue(i, 0); | |
54 | if (x < range[0] || x > range[1]) continue; | |
55 | ||
56 | var y = g.getValue(i, series); | |
57 | if (y == null) continue; | |
58 | if (y.length == 2) { | |
59 | // using fractions | |
60 | y = y[0] / y[1]; | |
61 | } | |
62 | ||
63 | num++; | |
64 | sum_x += x; | |
65 | sum_y += y; | |
66 | sum_xy += x * y; | |
67 | sum_x2 += x * x; | |
68 | } | |
69 | ||
70 | var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num); | |
71 | var b = (sum_y - a * sum_x) / num; | |
72 | ||
73 | coeffs[series] = [b, a]; | |
74 | if (typeof(console) != 'undefined') { | |
75 | console.log("coeffs(" + series + "): [" + b + ", " + a + "]"); | |
76 | } | |
77 | ||
78 | g.updateOptions({}); // forces a redraw. | |
79 | } | |
80 | ||
81 | function clearLines() { | |
82 | for (var i = 0; i < coeffs.length; i++) coeffs[i] = null; | |
83 | g.updateOptions({}); | |
84 | } | |
85 | ||
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86 | function toHex(rgb) { |
87 | return 'rgb(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ')'; | |
88 | } | |
89 | ||
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90 | function drawLines(ctx, area, layout) { |
91 | if (typeof(g) == 'undefined') return; // won't be set on the initial draw. | |
92 | ||
93 | var range = g.xAxisRange(); | |
94 | for (var i = 0; i < coeffs.length; i++) { | |
95 | if (!coeffs[i]) continue; | |
96 | var a = coeffs[i][1]; | |
97 | var b = coeffs[i][0]; | |
98 | ||
99 | var x1 = range[0]; | |
100 | var y1 = a * x1 + b; | |
101 | var x2 = range[1]; | |
102 | var y2 = a * x2 + b; | |
103 | ||
104 | // Scale up to percentages, rather than fractions. | |
105 | y1 *= 100; | |
106 | y2 *= 100; | |
107 | ||
108 | var p1 = g.toDomCoords(x1, y1); | |
109 | var p2 = g.toDomCoords(x2, y2); | |
110 | ||
0a171c09 | 111 | var c = Dygraph.toRGB_(g.getColors()[i - 1]); |
d1dfab80 DV |
112 | c.r = Math.floor(255 - 0.5 * (255 - c.r)); |
113 | c.g = Math.floor(255 - 0.5 * (255 - c.g)); | |
114 | c.b = Math.floor(255 - 0.5 * (255 - c.b)); | |
0a171c09 | 115 | var color = toHex(c); |
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116 | ctx.save(); |
117 | ctx.strokeStyle = color; | |
0a171c09 | 118 | ctx.lineWidth = 2.0; |
d1dfab80 DV |
119 | ctx.beginPath(); |
120 | ctx.moveTo(p1[0], p1[1]); | |
121 | ctx.lineTo(p2[0], p2[1]); | |
122 | ctx.closePath(); | |
123 | ctx.stroke(); | |
124 | ctx.restore(); | |
125 | } | |
126 | } | |
127 | ||
128 | </script> | |
129 | ||
130 | <div style="position: absolute; left: 500px; top: 150px;"> | |
131 | <input type=button style="color: green;" value="Regression (Y1)" onClick="regression(1)" /> | |
132 | <br/><br/> | |
133 | <input type=button style="color: blue;" value="Regression (Y2)" onClick="regression(2)" /> | |
134 | <br/><br/> | |
135 | <input type=button value="Clear Lines" onClick="clearLines()" /> | |
136 | </div> | |
137 | </body> | |
138 | </html> |