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     <!--
  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 = [];
  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       }
  35       var labels = ['X', 'Y1', 'Y2'];
  36       var orig_colors = [];
  37
  38       g = new Dygraph(
  39               document.getElementById("demodiv"),
  40               data,
  41               {
  42                 labels: labels,
  43                 drawPoints: true,
  44                 strokeWidth: 0.0,
  45                 drawCallback: function(g, is_initial) {
  46                   if (!is_initial) return;
  47                   var c = g.getColors();
  48                   for (var i = 0; i < c.length; i++) orig_colors.push(c[i]);
  49                 }
  50               }
  51           );
  52
  53       // coefficients of regression for each series.
  54       // if coeffs = [ null, [1, 2], null ] then we draw a regression for series 1
  55       // only. The regression line is y = 1 + 2 * x.
  56       var coeffs = [ null, null, null ];
  57       function regression(series) {
  58         // Only run the regression over visible points.
  59         var range = g.xAxisRange();
  60
  61         var sum_xy = 0.0, sum_x = 0.0, sum_y = 0.0, sum_x2 = 0.0, num = 0;
  62         for (var i = 0; i < data.length; i++) {
  63           var x = data[i][0];
  64           if (x < range[0] || x > range[1]) continue;
  65
  66           var y = data[i][series];
  67           if (y == null) continue;
  68           if (y.length == 2) {
  69             // using fractions
  70             y = y[0] / y[1];
  71           }
  72
  73           num++;
  74           sum_x += x;
  75           sum_y += y;
  76           sum_xy += x * y;
  77           sum_x2 += x * x;
  78         }
  79
  80         var a = (sum_xy - sum_x * sum_y / num) / (sum_x2 - sum_x * sum_x / num);
  81         var b = (sum_y - a * sum_x) / num;
  82
  83         coeffs[series] = [b, a];
  84         if (typeof(console) != 'undefined') {
  85           console.log("coeffs(" + series + "): [" + b + ", " + a + "]");
  86         }
  87
  88         updateChart();
  89       }
  90
  91       function updateChart() {
  92         // Generate a new data set with the regression lines.
  93         var new_labels = [];
  94         var new_colors = [];
  95         var new_opts = {};
  96         for (var i = 0; i < labels.length; i++) {
  97           new_labels.push(labels[i]);
  98           if (i) new_colors.push(orig_colors[i - 1]);
  99           if (coeffs[i]) {
 100             // Darken the series by 50% to generate its regression.
 101             var label = labels[i] + " Regression";
 102             new_labels.push(label);
 103             var c = new RGBColorParser(orig_colors[i - 1]);
 104             c.r = Math.floor(255 - 0.5 * (255 - c.r));
 105             c.g = Math.floor(255 - 0.5 * (255 - c.g));
 106             c.b = Math.floor(255 - 0.5 * (255 - c.b));
 107             new_colors.push(c.toHex());
 108             new_opts[label] = {
 109               drawPoints: false,
 110               strokeWidth: 1.0
 111             };
 112           }
 113         }
 114
 115         var new_data = [];
 116         for (var i = 0; i < data.length; i++) {
 117           new_data.push([]);
 118           for (var j = 0; j < data[i].length; j++) {
 119             new_data[i].push(data[i][j]);
 120             if (coeffs[j]) {
 121               new_data[i].push(coeffs[j][0] + coeffs[j][1] * data[i][0]);
 122             }
 123           }
 124         }
 125
 126         new_opts.file = new_data;
 127         new_opts.labels = new_labels;
 128         new_opts.colors = new_colors;
 129         g.updateOptions(new_opts);
 130       }
 131
 132       function clearLines() {
 133         for (var i = 0; i < coeffs.length; i++) coeffs[i] = null;
 134         updateChart();
 135       }
 136
 137     </script>
 138
 139     <div style="position: absolute; left: 500px; top: 150px;">
 140     <input type=button style="color: green;" value="Regression (Y1)" onClick="regression(1)" />
 141     <br/><br/>
 142     <input type=button style="color: blue;" value="Regression (Y2)" onClick="regression(2)" />
 143     <br/><br/>
 144     <input type=button value="Clear Lines" onClick="clearLines()" />
 145     </div>
 146 </body>
 147 </html>