| | 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 = "X,Y1,Y2\n"; |
| | 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 | data += i + "," + i + "/120," + (i*(120-i)) + "/" + (60*60) + "\n"; |
| | 31 | } |
| | 32 | |
| | 33 | g = new Dygraph( |
| | 34 | document.getElementById("demodiv"), |
| | 35 | data, |
| | 36 | { |
| | 37 | underlayCallback: drawLines, |
| | 38 | drawPoints: true, |
| | 39 | strokeWidth: 0.0, |
| | 40 | fractions: true, |
| | 41 | errorBars: true |
| | 42 | } |
| | 43 | ); |
| | 44 | |
| | 45 | // coefficients of regression for each series. |
| | 46 | // if coeffs = [ null, [1, 2], null ] then we draw a regression for series 1 |
| | 47 | // only. The regression line is y = 1 + 2 * x. |
| | 48 | var coeffs = [ null, null, null ]; |
| | 49 | function regression(series) { |
| | 50 | // Only run the regression over visible points. |
| | 51 | var range = g.xAxisRange(); |
| | 52 | |
| | 53 | var sum_xy = 0.0, sum_x = 0.0, sum_y = 0.0, sum_x2 = 0.0, num = 0; |
| | 54 | for (var i = 0; i < g.numRows(); i++) { |
| | 55 | var x = g.getValue(i, 0); |
| | 56 | if (x < range[0] || x > range[1]) continue; |
| | 57 | |
| | 58 | var y = g.getValue(i, series); |
| | 59 | if (y == null) continue; |
| | 60 | |
| | 61 | num++; |
| | 62 | sum_x += x; |
| | 63 | sum_y += y; |
| | 64 | sum_xy += x * y; |
| | 65 | sum_x2 += x * x; |
| | 66 | } |
| | 67 | |
| | 68 | var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num); |
| | 69 | var b = (sum_y - a * sum_x) / num; |
| | 70 | |
| | 71 | coeffs[series] = [b, a]; |
| | 72 | if (typeof(console) != 'undefined') { |
| | 73 | console.log("coeffs(" + series + "): [" + b + ", " + a + "]"); |
| | 74 | } |
| | 75 | |
| | 76 | g.updateOptions({}); // forces a redraw. |
| | 77 | } |
| | 78 | |
| | 79 | function clearLines() { |
| | 80 | for (var i = 0; i < coeffs.length; i++) coeffs[i] = null; |
| | 81 | g.updateOptions({}); |
| | 82 | } |
| | 83 | |
| | 84 | function drawLines(ctx, area, layout) { |
| | 85 | if (typeof(g) == 'undefined') return; // won't be set on the initial draw. |
| | 86 | |
| | 87 | var range = g.xAxisRange(); |
| | 88 | for (var i = 0; i < coeffs.length; i++) { |
| | 89 | if (!coeffs[i]) continue; |
| | 90 | var a = coeffs[i][1]; |
| | 91 | var b = coeffs[i][0]; |
| | 92 | |
| | 93 | var x1 = range[0]; |
| | 94 | var y1 = a * x1 + b; |
| | 95 | var x2 = range[1]; |
| | 96 | var y2 = a * x2 + b; |
| | 97 | |
| | 98 | var p1 = g.toDomCoords(x1, y1); |
| | 99 | var p2 = g.toDomCoords(x2, y2); |
| | 100 | |
| | 101 | var c = new RGBColor(g.getColors()[i - 1]); |
| | 102 | c.r = Math.floor(255 - 0.5 * (255 - c.r)); |
| | 103 | c.g = Math.floor(255 - 0.5 * (255 - c.g)); |
| | 104 | c.b = Math.floor(255 - 0.5 * (255 - c.b)); |
| | 105 | var color = c.toHex(); |
| | 106 | ctx.save(); |
| | 107 | ctx.strokeStyle = color; |
| | 108 | ctx.lineWidth = 1.0; |
| | 109 | ctx.beginPath(); |
| | 110 | ctx.moveTo(p1[0], p1[1]); |
| | 111 | ctx.lineTo(p2[0], p2[1]); |
| | 112 | ctx.closePath(); |
| | 113 | ctx.stroke(); |
| | 114 | ctx.restore(); |
| | 115 | } |
| | 116 | } |
| | 117 | |
| | 118 | </script> |
| | 119 | |
| | 120 | <div style="position: absolute; left: 500px; top: 150px;"> |
| | 121 | <input type=button style="color: green;" value="Regression (Y1)" onClick="regression(1)" /> |
| | 122 | <br/><br/> |
| | 123 | <input type=button style="color: blue;" value="Regression (Y2)" onClick="regression(2)" /> |
| | 124 | <br/><br/> |
| | 125 | <input type=button value="Clear Lines" onClick="clearLines()" /> |
| | 126 | </div> |
| | 127 | </body> |
| | 128 | </html> |
projects / dygraphs.git / blame_incremental