tests/linear-regression-addseries.html

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