datahandler/bars-fractions.js

   1 /**
   2  * @license
   3  * Copyright 2013 David Eberlein (david.eberlein@ch.sauter-bc.com)
   4  * MIT-licensed (http://opensource.org/licenses/MIT)
   5  */
   6
   7 /**
   8  * @fileoverview DataHandler implementation for the combination
   9  * of error bars and fractions options.
  10  * @author David Eberlein (david.eberlein@ch.sauter-bc.com)
  11  */
  12
  13 (function() {
  14   /*global Dygraph:false */
  15   "use strict";
  16
  17   var FractionsBarsHandler = Dygraph.DataHandler();
  18   FractionsBarsHandler.prototype = Dygraph.DataHandlers.createHandler("bars");
  19   Dygraph.DataHandlers.registerHandler("bars-fractions", FractionsBarsHandler);
  20   // errorBars
  21   FractionsBarsHandler.prototype.extractSeries = function(rawData, i, options) {
  22     // TODO(danvk): pre-allocate series here.
  23     var series = [];
  24     var x, y, point, num, den, value, stddev, variance;
  25     var mult = 100.0;
  26     var sigma = options.get("sigma");
  27     var logScale = options.get('logscale');
  28     for ( var j = 0; j < rawData.length; j++) {
  29       x = rawData[j][0];
  30       point = rawData[j][i];
  31       if (logScale && point !== null) {
  32         // On the log scale, points less than zero do not exist.
  33         // This will create a gap in the chart.
  34         if (point[0] <= 0 || point[1] <= 0) {
  35           point = null;
  36         }
  37       }
  38       // Extract to the unified data format.
  39       if (point !== null) {
  40         num = point[0];
  41         den = point[1];
  42         if (num !== null && !isNaN(num)) {
  43           value = den ? num / den : 0.0;
  44           stddev = den ? sigma * Math.sqrt(value * (1 - value) / den) : 1.0;
  45           variance = mult * stddev;
  46           y = mult * value;
  47           // preserve original values in extras for further filtering
  48           series.push([ x, y, [ y - variance, y + variance, num, den ] ]);
  49         } else {
  50           series.push([ x, num, [ num, num, num, den ] ]);
  51         }
  52       } else {
  53         series.push([ x, null, [ null, null, null, null ] ]);
  54       }
  55     }
  56     return series;
  57   };
  58
  59   FractionsBarsHandler.prototype.rollingAverage = function(originalData, rollPeriod,
  60       options) {
  61     rollPeriod = Math.min(rollPeriod, originalData.length);
  62     var rollingData = [];
  63     var sigma = options.get("sigma");
  64     var wilsonInterval = options.get("wilsonInterval");
  65
  66     var low, high, i, stddev;
  67     var num = 0;
  68     var den = 0; // numerator/denominator
  69     var mult = 100.0;
  70     for (i = 0; i < originalData.length; i++) {
  71       num += originalData[i][2][2];
  72       den += originalData[i][2][3];
  73       if (i - rollPeriod >= 0) {
  74         num -= originalData[i - rollPeriod][2][2];
  75         den -= originalData[i - rollPeriod][2][3];
  76       }
  77
  78       var date = originalData[i][0];
  79       var value = den ? num / den : 0.0;
  80       if (wilsonInterval) {
  81         // For more details on this confidence interval, see:
  82         // http://en.wikipedia.org/wiki/Binomial_confidence_interval
  83         if (den) {
  84           var p = value < 0 ? 0 : value, n = den;
  85           var pm = sigma * Math.sqrt(p * (1 - p) / n + sigma * sigma / (4 * n * n));
  86           var denom = 1 + sigma * sigma / den;
  87           low = (p + sigma * sigma / (2 * den) - pm) / denom;
  88           high = (p + sigma * sigma / (2 * den) + pm) / denom;
  89           rollingData[i] = [ date, p * mult,
  90               [ low * mult, high * mult ] ];
  91         } else {
  92           rollingData[i] = [ date, 0, [ 0, 0 ] ];
  93         }
  94       } else {
  95         stddev = den ? sigma * Math.sqrt(value * (1 - value) / den) : 1.0;
  96         rollingData[i] = [ date, mult * value,
  97                            [ mult * (value - stddev), mult * (value + stddev) ] ];
  98       }
  99     }
 100
 101     return rollingData;
 102   };
 103 })();