tests/linear-regression-fractions.html

   1 <!DOCTYPE html>
   2 <html>
   3   <head>
   4     <meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7; IE=EmulateIE9">
   5     <title>Linear Regression</title>
   6     <!--[if IE]>
   7     <script type="text/javascript" src="../excanvas.js"></script>
   8     <![endif]-->
   9     <!--
  10     For production (minified) code, use:
  11     <script type="text/javascript" src="dygraph-combined.js"></script>
  12     -->
  13     <script type="text/javascript" src="../dygraph-dev.js"></script>
  14
  15     <style type="text/css">
  16     body { max-width: 640 px; }
  17     </style>
  18   </head>
  19   <body>
  20     <h2>Linear Regression Demo</h2>
  21     <p>Click the buttons to generate linear regressions over either data
  22     series. If you zoom in and click the regression button, the regression will
  23     only be run over visible points. Zoom back out to see what the local
  24     regression looks like over the full data.</p>
  25
  26     <div id="demodiv" style="width: 480px; height: 320px;"></div>
  27
  28     <script type="text/javascript">
  29       var data = "X,Y1,Y2\n";
  30       for (var i = 0; i < 120; i++) {
  31         // data.push([i,
  32         //            i / 5.0 + 10.0 * Math.sin(i / 3.0),
  33         //            30.0 - i / 5.0 - 10.0 * Math.sin(i / 3.0 + 1.0)]);
  34         data += i + "," + i + "/120," + (i*(120-i)) + "/" + (60*60) + "\n";
  35       }
  36
  37       g = new Dygraph(
  38               document.getElementById("demodiv"),
  39               data,
  40               {
  41                 underlayCallback: drawLines,
  42                 drawPoints: true,
  43                 strokeWidth: 0.0,
  44                 fractions: true,
  45                 errorBars: true,
  46                 pointSize: 1
  47               }
  48           );
  49
  50       // coefficients of regression for each series.
  51       // if coeffs = [ null, [1, 2], null ] then we draw a regression for series 1
  52       // only. The regression line is y = 1 + 2 * x.
  53       var coeffs = [ null, null, null ];
  54       function regression(series) {
  55         // Only run the regression over visible points.
  56         var range = g.xAxisRange();
  57
  58         var sum_xy = 0.0, sum_x = 0.0, sum_y = 0.0, sum_x2 = 0.0, num = 0;
  59         for (var i = 0; i < g.numRows(); i++) {
  60           var x = g.getValue(i, 0);
  61           if (x < range[0] || x > range[1]) continue;
  62
  63           var y = g.getValue(i, series);
  64           if (y == null) continue;
  65           if (y.length == 2) {
  66             // using fractions
  67             y = y[0] / y[1];
  68           }
  69
  70           num++;
  71           sum_x += x;
  72           sum_y += y;
  73           sum_xy += x * y;
  74           sum_x2 += x * x;
  75         }
  76
  77         var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num);
  78         var b = (sum_y - a * sum_x) / num;
  79
  80         coeffs[series] = [b, a];
  81         if (typeof(console) != 'undefined') {
  82           console.log("coeffs(" + series + "): [" + b + ", " + a + "]");
  83         }
  84
  85         g.updateOptions({});  // forces a redraw.
  86       }
  87
  88       function clearLines() {
  89         for (var i = 0; i < coeffs.length; i++) coeffs[i] = null;
  90         g.updateOptions({});
  91       }
  92
  93       function toHex(rgb) {
  94         return 'rgb(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ')';
  95       }
  96
  97       function drawLines(ctx, area, layout) {
  98         if (typeof(g) == 'undefined') return;  // won't be set on the initial draw.
  99
 100         var range = g.xAxisRange();
 101         for (var i = 0; i < coeffs.length; i++) {
 102           if (!coeffs[i]) continue;
 103           var a = coeffs[i][1];
 104           var b = coeffs[i][0];
 105
 106           var x1 = range[0];
 107           var y1 = a * x1 + b;
 108           var x2 = range[1];
 109           var y2 = a * x2 + b;
 110
 111           // Scale up to percentages, rather than fractions.
 112           y1 *= 100;
 113           y2 *= 100;
 114
 115           var p1 = g.toDomCoords(x1, y1);
 116           var p2 = g.toDomCoords(x2, y2);
 117
 118           var c = Dygraph.toRGB_(g.getColors()[i - 1]);
 119           c.r = Math.floor(255 - 0.5 * (255 - c.r));
 120           c.g = Math.floor(255 - 0.5 * (255 - c.g));
 121           c.b = Math.floor(255 - 0.5 * (255 - c.b));
 122           var color = toHex(c);
 123           ctx.save();
 124           ctx.strokeStyle = color;
 125           ctx.lineWidth = 2.0;
 126           ctx.beginPath();
 127           ctx.moveTo(p1[0], p1[1]);
 128           ctx.lineTo(p2[0], p2[1]);
 129           ctx.closePath();
 130           ctx.stroke();
 131           ctx.restore();
 132         }
 133       }
 134
 135     </script>
 136
 137     <div style="position: absolute; left: 500px; top: 150px;">
 138     <input type=button style="color: green;" value="Regression (Y1)" onClick="regression(1)" />
 139     <br/><br/>
 140     <input type=button style="color: blue;" value="Regression (Y2)" onClick="regression(2)" />
 141     <br/><br/>
 142     <input type=button value="Clear Lines" onClick="clearLines()" />
 143     </div>
 144 </body>
 145 </html>