tests/linear-regression-addseries.html

   1 <!DOCTYPE html>
   2 <html>
   3   <head>
   4     <link rel="stylesheet" href="../dist/dygraph.css">
   5     <title>Linear Regression</title>
   6     <script type="text/javascript" src="../dist/dygraph.js"></script>
   7
   8     <style type="text/css">
   9     body { max-width: 640 px; }
  10     </style>
  11   </head>
  12   <body>
  13     <h2>Linear Regression Demo</h2>
  14     <p>Click the buttons to generate linear regressions over either data
  15     series. If you zoom in and click the regression button, the regression will
  16     only be run over visible points. Zoom back out to see what the local
  17     regression looks like over the full data.</p>
  18
  19     <div id="demodiv" style="width: 480px; height: 320px;"></div>
  20
  21     <script type="text/javascript">
  22       var data = [];
  23       for (var i = 0; i < 120; i++) {
  24         data.push([i,
  25                    i / 5.0 + 10.0 * Math.sin(i / 3.0),
  26                    30.0 - i / 5.0 - 10.0 * Math.sin(i / 3.0 + 1.0)]);
  27       }
  28       var labels = ['X', 'Y1', 'Y2'];
  29       var orig_colors = [];
  30
  31       g = new Dygraph(
  32               document.getElementById("demodiv"),
  33               data,
  34               {
  35                 labels: labels,
  36                 drawPoints: true,
  37                 strokeWidth: 0.0,
  38                 drawCallback: function(g, is_initial) {
  39                   if (!is_initial) return;
  40                   var c = g.getColors();
  41                   for (var i = 0; i < c.length; i++) orig_colors.push(c[i]);
  42                 }
  43               }
  44           );
  45
  46       // coefficients of regression for each series.
  47       // if coeffs = [ null, [1, 2], null ] then we draw a regression for series 1
  48       // only. The regression line is y = 1 + 2 * x.
  49       var coeffs = [ null, null, null ];
  50       function regression(series) {
  51         // Only run the regression over visible points.
  52         var range = g.xAxisRange();
  53
  54         var sum_xy = 0.0, sum_x = 0.0, sum_y = 0.0, sum_x2 = 0.0, num = 0;
  55         for (var i = 0; i < data.length; i++) {
  56           var x = data[i][0];
  57           if (x < range[0] || x > range[1]) continue;
  58
  59           var y = data[i][series];
  60           if (y == null) continue;
  61           if (y.length == 2) {
  62             // using fractions
  63             y = y[0] / y[1];
  64           }
  65
  66           num++;
  67           sum_x += x;
  68           sum_y += y;
  69           sum_xy += x * y;
  70           sum_x2 += x * x;
  71         }
  72
  73         var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num);
  74         var b = (sum_y - a * sum_x) / num;
  75
  76         coeffs[series] = [b, a];
  77         if (typeof(console) != 'undefined') {
  78           console.log("coeffs(" + series + "): [" + b + ", " + a + "]");
  79         }
  80
  81         updateChart();
  82       }
  83
  84       function toHex(rgb) {
  85         return 'rgb(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ')';
  86       }
  87
  88       function updateChart() {
  89         // Generate a new data set with the regression lines.
  90         var new_labels = [];
  91         var new_colors = [];
  92         var new_opts = {};
  93         for (var i = 0; i < labels.length; i++) {
  94           new_labels.push(labels[i]);
  95           if (i) new_colors.push(orig_colors[i - 1]);
  96           if (coeffs[i]) {
  97             // Darken the series by 50% to generate its regression.
  98             var label = labels[i] + " Regression";
  99             new_labels.push(label);
 100             var c = Dygraph.toRGB_(orig_colors[i - 1]);
 101             c.r = Math.floor(255 - 0.5 * (255 - c.r));
 102             c.g = Math.floor(255 - 0.5 * (255 - c.g));
 103             c.b = Math.floor(255 - 0.5 * (255 - c.b));
 104             new_colors.push(toHex(c));
 105             new_opts[label] = {
 106               drawPoints: false,
 107               strokeWidth: 1.0
 108             };
 109           }
 110         }
 111
 112         var new_data = [];
 113         for (var i = 0; i < data.length; i++) {
 114           new_data.push([]);
 115           for (var j = 0; j < data[i].length; j++) {
 116             new_data[i].push(data[i][j]);
 117             if (coeffs[j]) {
 118               new_data[i].push(coeffs[j][0] + coeffs[j][1] * data[i][0]);
 119             }
 120           }
 121         }
 122
 123         new_opts.file = new_data;
 124         new_opts.labels = new_labels;
 125         new_opts.colors = new_colors;
 126         g.updateOptions(new_opts);
 127       }
 128
 129       function clearLines() {
 130         for (var i = 0; i < coeffs.length; i++) coeffs[i] = null;
 131         updateChart();
 132       }
 133
 134     </script>
 135
 136     <div style="position: absolute; left: 500px; top: 150px;">
 137     <input type=button style="color: green;" value="Regression (Y1)" onClick="regression(1)" />
 138     <br/><br/>
 139     <input type=button style="color: blue;" value="Regression (Y2)" onClick="regression(2)" />
 140     <br/><br/>
 141     <input type=button value="Clear Lines" onClick="clearLines()" />
 142     </div>
 143 </body>
 144 </html>