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                 strokeWidth: 0.0,
  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;
  64           if (y.length == 2) {
  65             // using fractions
  66             y = y[0] / y[1];
  67           }
  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];
  80         if (typeof(console) != 'undefined') {
  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 = [];
  91         var new_opts = {};
  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.
  97             var label = labels[i] + " Regression";
  98             new_labels.push(label);
  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());
 104             new_opts[label] = {
 105               drawPoints: false,
 106               strokeWidth: 1.0
 107             };
 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
 122         new_opts.file = new_data;
 123         new_opts.labels = new_labels;
 124         new_opts.colors = new_colors;
 125         g.updateOptions(new_opts);
 126       }
 127
 128       function clearLines() {
 129         for (var i = 0; i < coeffs.length; i++) coeffs[i] = null;
 130         updateChart();
 131       }
 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>