projects / dygraphs.git / blame
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|---|---|---|
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1 | <html> |
| 2 | <head> | |
| 3 | <title>Linear Regression</title> | |
| 4 | <!--[if IE]> | |
| a2b2c3a1 | 5 | <script type="text/javascript" src="../excanvas.js"></script> |
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6 | <![endif]--> |
| 7 | <script type="text/javascript" src="../strftime/strftime-min.js"></script> | |
| 8 | <script type="text/javascript" src="../rgbcolor/rgbcolor.js"></script> | |
| 9 | <script type="text/javascript" src="../dygraph-canvas.js"></script> | |
| 10 | <script type="text/javascript" src="../dygraph.js"></script> | |
| 11 | <style type="text/css"> | |
| 12 | body { max-width: 640 px; } | |
| 13 | </style> | |
| 14 | </head> | |
| 15 | <body> | |
| 16 | <h2>Linear Regression Demo</h2> | |
| 17 | <p>Click the buttons to generate linear regressions over either data | |
| 18 | series. If you zoom in and click the regression button, the regression will | |
| 19 | only be run over visible points. Zoom back out to see what the local | |
| 20 | regression looks like over the full data.</p> | |
| 21 | ||
| 22 | <div id="demodiv" style="width: 480px; height: 320px;"></div> | |
| 23 | ||
| 24 | <script type="text/javascript"> | |
| 25 | var data = []; | |
| 26 | for (var i = 0; i < 120; i++) { | |
| 27 | data.push([i, | |
| 28 | i / 5.0 + 10.0 * Math.sin(i / 3.0), | |
| 29 | 30.0 - i / 5.0 - 10.0 * Math.sin(i / 3.0 + 1.0)]); | |
| 30 | } | |
| 31 | var labels = ['X', 'Y1', 'Y2']; | |
| 32 | var orig_colors = []; | |
| 33 | ||
| 34 | g = new Dygraph( | |
| 35 | document.getElementById("demodiv"), | |
| 36 | data, | |
| 37 | { | |
| 38 | labels: labels, | |
| 39 | drawPoints: true, | |
| de0445fc | 40 | strokeWidth: 0.0, |
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41 | drawCallback: function(g, is_initial) { |
| 42 | if (!is_initial) return; | |
| 43 | var c = g.getColors(); | |
| 44 | for (var i = 0; i < c.length; i++) orig_colors.push(c[i]); | |
| 45 | } | |
| 46 | } | |
| 47 | ); | |
| 48 | ||
| 49 | // coefficients of regression for each series. | |
| 50 | // if coeffs = [ null, [1, 2], null ] then we draw a regression for series 1 | |
| 51 | // only. The regression line is y = 1 + 2 * x. | |
| 52 | var coeffs = [ null, null, null ]; | |
| 53 | function regression(series) { | |
| 54 | // Only run the regression over visible points. | |
| 55 | var range = g.xAxisRange(); | |
| 56 | ||
| 57 | var sum_xy = 0.0, sum_x = 0.0, sum_y = 0.0, sum_x2 = 0.0, num = 0; | |
| 58 | for (var i = 0; i < data.length; i++) { | |
| 59 | var x = data[i][0]; | |
| 60 | if (x < range[0] || x > range[1]) continue; | |
| 61 | ||
| 62 | var y = data[i][series]; | |
| 63 | if (y == null) continue; | |
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64 | if (y.length == 2) { |
| 65 | // using fractions | |
| 66 | y = y[0] / y[1]; | |
| 67 | } | |
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68 | |
| 69 | num++; | |
| 70 | sum_x += x; | |
| 71 | sum_y += y; | |
| 72 | sum_xy += x * y; | |
| 73 | sum_x2 += x * x; | |
| 74 | } | |
| 75 | ||
| 76 | var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num); | |
| 77 | var b = (sum_y - a * sum_x) / num; | |
| 78 | ||
| 79 | coeffs[series] = [b, a]; | |
| 4df1af70 | 80 | if (typeof(console) != 'undefined') { |
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81 | console.log("coeffs(" + series + "): [" + b + ", " + a + "]"); |
| 82 | } | |
| 83 | ||
| 84 | updateChart(); | |
| 85 | } | |
| 86 | ||
| 87 | function updateChart() { | |
| 88 | // Generate a new data set with the regression lines. | |
| 89 | var new_labels = []; | |
| 90 | var new_colors = []; | |
| de0445fc | 91 | var new_opts = {}; |
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92 | for (var i = 0; i < labels.length; i++) { |
| 93 | new_labels.push(labels[i]); | |
| 94 | if (i) new_colors.push(orig_colors[i - 1]); | |
| 95 | if (coeffs[i]) { | |
| 96 | // Darken the series by 50% to generate its regression. | |
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97 | var label = labels[i] + " Regression"; |
| 98 | new_labels.push(label); | |
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99 | var c = new RGBColor(orig_colors[i - 1]); |
| 100 | c.r = Math.floor(255 - 0.5 * (255 - c.r)); | |
| 101 | c.g = Math.floor(255 - 0.5 * (255 - c.g)); | |
| 102 | c.b = Math.floor(255 - 0.5 * (255 - c.b)); | |
| 103 | new_colors.push(c.toHex()); | |
| 227b93cc | 104 | new_opts[label] = { |
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105 | drawPoints: false, |
| 106 | strokeWidth: 1.0 | |
| 107 | }; | |
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108 | } |
| 109 | } | |
| 110 | ||
| 111 | var new_data = []; | |
| 112 | for (var i = 0; i < data.length; i++) { | |
| 113 | new_data.push([]); | |
| 114 | for (var j = 0; j < data[i].length; j++) { | |
| 115 | new_data[i].push(data[i][j]); | |
| 116 | if (coeffs[j]) { | |
| 117 | new_data[i].push(coeffs[j][0] + coeffs[j][1] * data[i][0]); | |
| 118 | } | |
| 119 | } | |
| 120 | } | |
| 121 | ||
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122 | new_opts.file = new_data; |
| 123 | new_opts.labels = new_labels; | |
| 124 | new_opts.colors = new_colors; | |
| 125 | g.updateOptions(new_opts); | |
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126 | } |
| 127 | ||
| 128 | function clearLines() { | |
| 129 | for (var i = 0; i < coeffs.length; i++) coeffs[i] = null; | |
| 130 | updateChart(); | |
| 131 | } | |
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132 | |
| 133 | </script> | |
| 134 | ||
| 135 | <div style="position: absolute; left: 500px; top: 150px;"> | |
| 136 | <input type=button style="color: green;" value="Regression (Y1)" onClick="regression(1)" /> | |
| 137 | <br/><br/> | |
| 138 | <input type=button style="color: blue;" value="Regression (Y2)" onClick="regression(2)" /> | |
| 139 | <br/><br/> | |
| 140 | <input type=button value="Clear Lines" onClick="clearLines()" /> | |
| 141 | </div> | |
| 142 | </body> | |
| 143 | </html> |