tests/linear-regression-addseries.html

   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       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,
  40                 drawCallback: function(g, is_initial) {
  41                   if (!is_initial) return;
  42                   var c = g.getColors();
  43                   for (var i = 0; i < c.length; i++) orig_colors.push(c[i]);
  44                 }
  45               }
  46           );
  47
  48       // coefficients of regression for each series.
  49       // if coeffs = [ null, [1, 2], null ] then we draw a regression for series 1
  50       // only. The regression line is y = 1 + 2 * x.
  51       var coeffs = [ null, null, null ];
  52       function regression(series) {
  53         // Only run the regression over visible points.
  54         var range = g.xAxisRange();
  55
  56         var sum_xy = 0.0, sum_x = 0.0, sum_y = 0.0, sum_x2 = 0.0, num = 0;
  57         for (var i = 0; i < data.length; i++) {
  58           var x = data[i][0];
  59           if (x < range[0] || x > range[1]) continue;
  60
  61           var y = data[i][series];
  62           if (y == null) continue;
  63
  64           num++;
  65           sum_x += x;
  66           sum_y += y;
  67           sum_xy += x * y;
  68           sum_x2 += x * x;
  69         }
  70
  71         var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num);
  72         var b = (sum_y - a * sum_x) / num;
  73
  74         coeffs[series] = [b, a];
  75         if (console) {
  76           console.log("coeffs(" + series + "): [" + b + ", " + a + "]");
  77         }
  78
  79         updateChart();
  80       }
  81
  82       function updateChart() {
  83         // Generate a new data set with the regression lines.
  84         var new_labels = [];
  85         var new_colors = [];
  86         for (var i = 0; i < labels.length; i++) {
  87           new_labels.push(labels[i]);
  88           if (i) new_colors.push(orig_colors[i - 1]);
  89           if (coeffs[i]) {
  90             // Darken the series by 50% to generate its regression.
  91             new_labels.push(labels[i] + " Regression");
  92             var c = new RGBColor(orig_colors[i - 1]);
  93             c.r = Math.floor(255 - 0.5 * (255 - c.r));
  94             c.g = Math.floor(255 - 0.5 * (255 - c.g));
  95             c.b = Math.floor(255 - 0.5 * (255 - c.b));
  96             new_colors.push(c.toHex());
  97           }
  98         }
  99
 100         var new_data = [];
 101         for (var i = 0; i < data.length; i++) {
 102           new_data.push([]);
 103           for (var j = 0; j < data[i].length; j++) {
 104             new_data[i].push(data[i][j]);
 105             if (coeffs[j]) {
 106               new_data[i].push(coeffs[j][0] + coeffs[j][1] * data[i][0]);
 107             }
 108           }
 109         }
 110
 111         // TODO(danvk): set colors intelligently.
 112
 113         g.updateOptions({
 114           file: new_data,
 115           labels: new_labels,
 116           colors: new_colors
 117         });
 118       }
 119
 120       function clearLines() {
 121         for (var i = 0; i < coeffs.length; i++) coeffs[i] = null;
 122         updateChart();
 123       }
 124
 125       // function drawLines(ctx, area, layout) {
 126       //   if (typeof(g) == 'undefined') return;  // won't be set on the initial draw.
 127
 128       //   var range = g.xAxisRange();
 129       //   for (var i = 0; i < coeffs.length; i++) {
 130       //     if (!coeffs[i]) continue;
 131       //     var a = coeffs[i][1];
 132       //     var b = coeffs[i][0];
 133
 134       //     var x1 = range[0];
 135       //     var y1 = a * x1 + b;
 136       //     var x2 = range[1];
 137       //     var y2 = a * x2 + b;
 138
 139       //     var p1 = g.toDomCoords(x1, y1);
 140       //     var p2 = g.toDomCoords(x2, y2);
 141
 142       //     var color = g.getColors()[i - 1];
 143       //     ctx.save();
 144       //     ctx.strokeStyle = color;
 145       //     ctx.lineWidth = 1.0;
 146       //     ctx.beginPath();
 147       //     ctx.moveTo(p1[0], p1[1]);
 148       //     ctx.lineTo(p2[0], p2[1]);
 149       //     ctx.closePath();
 150       //     ctx.stroke();
 151       //     ctx.restore();
 152       //   }
 153       // }
 154
 155     </script>
 156
 157     <div style="position: absolute; left: 500px; top: 150px;">
 158     <input type=button style="color: green;" value="Regression (Y1)" onClick="regression(1)" />
 159     <br/><br/>
 160     <input type=button style="color: blue;" value="Regression (Y2)" onClick="regression(2)" />
 161     <br/><br/>
 162     <input type=button value="Clear Lines" onClick="clearLines()" />
 163     </div>
 164 </body>
 165 </html>