projects / dygraphs.git / blame
| Commit | Line | Data |
|---|---|---|
| 05a1d116 DV |
1 | <html> |
| 2 | <head> | |
| 3 | <title>Linear Regression</title> | |
| 4 | <!--[if IE]> | |
| 5 | <script type="text/javascript" src="excanvas.js"></script> | |
| 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 | ||
| 32 | g = new Dygraph( | |
| 33 | document.getElementById("demodiv"), | |
| 34 | data, | |
| 35 | { | |
| 36 | labels: ['X', 'Y1', 'Y2'], | |
| 37 | underlayCallback: drawLines, | |
| 38 | drawPoints: true | |
| 39 | } | |
| 40 | ); | |
| 41 | ||
| 42 | // coefficients of regression for each series. | |
| 43 | // if coeffs = [ null, [1, 2], null ] then we draw a regression for series 1 | |
| 44 | // only. The regression line is y = 1 + 2 * x. | |
| 45 | var coeffs = [ null, null, null ]; | |
| 46 | function regression(series) { | |
| 47 | // Only run the regression over visible points. | |
| 48 | var range = g.xAxisRange(); | |
| 49 | ||
| 50 | var sum_xy = 0.0, sum_x = 0.0, sum_y = 0.0, sum_x2 = 0.0, num = 0; | |
| 51 | for (var i = 0; i < g.numRows(); i++) { | |
| 52 | var x = g.getValue(i, 0); | |
| 53 | if (x < range[0] || x > range[1]) continue; | |
| 54 | ||
| 55 | var y = g.getValue(i, series); | |
| 56 | if (y == null) continue; | |
| 57 | ||
| 58 | num++; | |
| 59 | sum_x += x; | |
| 60 | sum_y += y; | |
| 61 | sum_xy += x * y; | |
| 62 | sum_x2 += x * x; | |
| 63 | } | |
| 64 | ||
| 65 | var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num); | |
| 66 | var b = (sum_y - a * sum_x) / num; | |
| 67 | ||
| 68 | coeffs[series] = [b, a]; | |
| 2a07b0ad DV |
69 | if (console) { |
| 70 | console.log("coeffs(" + series + "): [" + b + ", " + a + "]"); | |
| 71 | } | |
| 05a1d116 DV |
72 | |
| 73 | g.updateOptions({}); // forces a redraw. | |
| 74 | } | |
| 75 | ||
| 76 | function clearLines() { | |
| 77 | for (var i = 0; i < coeffs.length; i++) coeffs[i] = null; | |
| 78 | g.updateOptions({}); | |
| 79 | } | |
| 80 | ||
| 81 | function drawLines(ctx, area, layout) { | |
| 82 | if (typeof(g) == 'undefined') return; // won't be set on the initial draw. | |
| 83 | ||
| 84 | var range = g.xAxisRange(); | |
| 85 | for (var i = 0; i < coeffs.length; i++) { | |
| 86 | if (!coeffs[i]) continue; | |
| 87 | var a = coeffs[i][1]; | |
| 88 | var b = coeffs[i][0]; | |
| 89 | ||
| 90 | var x1 = range[0]; | |
| 91 | var y1 = a * x1 + b; | |
| 92 | var x2 = range[1]; | |
| 93 | var y2 = a * x2 + b; | |
| 94 | ||
| 95 | var p1 = g.toDomCoords(x1, y1); | |
| 96 | var p2 = g.toDomCoords(x2, y2); | |
| 97 | ||
| 34bbe78b DV |
98 | var c = new RGBColor(g.getColors()[i - 1]); |
| 99 | c.r = Math.floor(255 - 0.5 * (255 - c.r)); | |
| 100 | c.g = Math.floor(255 - 0.5 * (255 - c.g)); | |
| 101 | c.b = Math.floor(255 - 0.5 * (255 - c.b)); | |
| 102 | var color = c.toHex(); | |
| 05a1d116 DV |
103 | ctx.save(); |
| 104 | ctx.strokeStyle = color; | |
| 105 | ctx.lineWidth = 1.0; | |
| 106 | ctx.beginPath(); | |
| 107 | ctx.moveTo(p1[0], p1[1]); | |
| 108 | ctx.lineTo(p2[0], p2[1]); | |
| 109 | ctx.closePath(); | |
| 110 | ctx.stroke(); | |
| 111 | ctx.restore(); | |
| 112 | } | |
| 113 | } | |
| 114 | ||
| 115 | </script> | |
| 116 | ||
| 117 | <div style="position: absolute; left: 500px; top: 150px;"> | |
| 118 | <input type=button style="color: green;" value="Regression (Y1)" onClick="regression(1)" /> | |
| 119 | <br/><br/> | |
| 120 | <input type=button style="color: blue;" value="Regression (Y2)" onClick="regression(2)" /> | |
| 121 | <br/><br/> | |
| 122 | <input type=button value="Clear Lines" onClick="clearLines()" /> | |
| 123 | </div> | |
| 124 | </body> | |
| 125 | </html> |