tests/linear-regression-addseries.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     <script type="text/javascript" src="../strftime/strftime-min.js"></script>
  10     <script type="text/javascript" src="../rgbcolor/rgbcolor.js"></script>
  11     <script type="text/javascript" src="../dygraph-canvas.js"></script>
  12     <script type="text/javascript" src="../dygraph.js"></script>
  13     <style type="text/css">
  14     body { max-width: 640 px; }
  15     </style>
  16   </head>
  17   <body>
  18     <h2>Linear Regression Demo</h2>
  19     <p>Click the buttons to generate linear regressions over either data
  20     series. If you zoom in and click the regression button, the regression will
  21     only be run over visible points. Zoom back out to see what the local
  22     regression looks like over the full data.</p>
  23
  24     <div id="demodiv" style="width: 480px; height: 320px;"></div>
  25
  26     <script type="text/javascript">
  27       var data = [];
  28       for (var i = 0; i < 120; i++) {
  29         data.push([i,
  30                    i / 5.0 + 10.0 * Math.sin(i / 3.0),
  31                    30.0 - i / 5.0 - 10.0 * Math.sin(i / 3.0 + 1.0)]);
  32       }
  33       var labels = ['X', 'Y1', 'Y2'];
  34       var orig_colors = [];
  35
  36       g = new Dygraph(
  37               document.getElementById("demodiv"),
  38               data,
  39               {
  40                 labels: labels,
  41                 drawPoints: true,
  42                 strokeWidth: 0.0,
  43                 drawCallback: function(g, is_initial) {
  44                   if (!is_initial) return;
  45                   var c = g.getColors();
  46                   for (var i = 0; i < c.length; i++) orig_colors.push(c[i]);
  47                 }
  48               }
  49           );
  50
  51       // coefficients of regression for each series.
  52       // if coeffs = [ null, [1, 2], null ] then we draw a regression for series 1
  53       // only. The regression line is y = 1 + 2 * x.
  54       var coeffs = [ null, null, null ];
  55       function regression(series) {
  56         // Only run the regression over visible points.
  57         var range = g.xAxisRange();
  58
  59         var sum_xy = 0.0, sum_x = 0.0, sum_y = 0.0, sum_x2 = 0.0, num = 0;
  60         for (var i = 0; i < data.length; i++) {
  61           var x = data[i][0];
  62           if (x < range[0] || x > range[1]) continue;
  63
  64           var y = data[i][series];
  65           if (y == null) continue;
  66           if (y.length == 2) {
  67             // using fractions
  68             y = y[0] / y[1];
  69           }
  70
  71           num++;
  72           sum_x += x;
  73           sum_y += y;
  74           sum_xy += x * y;
  75           sum_x2 += x * x;
  76         }
  77
  78         var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num);
  79         var b = (sum_y - a * sum_x) / num;
  80
  81         coeffs[series] = [b, a];
  82         if (typeof(console) != 'undefined') {
  83           console.log("coeffs(" + series + "): [" + b + ", " + a + "]");
  84         }
  85
  86         updateChart();
  87       }
  88
  89       function updateChart() {
  90         // Generate a new data set with the regression lines.
  91         var new_labels = [];
  92         var new_colors = [];
  93         var new_opts = {};
  94         for (var i = 0; i < labels.length; i++) {
  95           new_labels.push(labels[i]);
  96           if (i) new_colors.push(orig_colors[i - 1]);
  97           if (coeffs[i]) {
  98             // Darken the series by 50% to generate its regression.
  99             var label = labels[i] + " Regression";
 100             new_labels.push(label);
 101             var c = new RGBColor(orig_colors[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             new_colors.push(c.toHex());
 106             new_opts[label] = {
 107               drawPoints: false,
 108               strokeWidth: 1.0
 109             };
 110           }
 111         }
 112
 113         var new_data = [];
 114         for (var i = 0; i < data.length; i++) {
 115           new_data.push([]);
 116           for (var j = 0; j < data[i].length; j++) {
 117             new_data[i].push(data[i][j]);
 118             if (coeffs[j]) {
 119               new_data[i].push(coeffs[j][0] + coeffs[j][1] * data[i][0]);
 120             }
 121           }
 122         }
 123
 124         new_opts.file = new_data;
 125         new_opts.labels = new_labels;
 126         new_opts.colors = new_colors;
 127         g.updateOptions(new_opts);
 128       }
 129
 130       function clearLines() {
 131         for (var i = 0; i < coeffs.length; i++) coeffs[i] = null;
 132         updateChart();
 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>