src/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
  15 /*global Dygraph:false */
  16 "use strict";
  17
  18 /**
  19  * @constructor
  20  * @extends Dygraph.DataHandlers.BarsHandler
  21  */
  22 Dygraph.DataHandlers.FractionsBarsHandler = function() {
  23 };
  24
  25 var FractionsBarsHandler = Dygraph.DataHandlers.FractionsBarsHandler;
  26 FractionsBarsHandler.prototype = new Dygraph.DataHandlers.BarsHandler();
  27
  28 /** @inheritDoc */
  29 FractionsBarsHandler.prototype.extractSeries = function(rawData, i, options) {
  30   // TODO(danvk): pre-allocate series here.
  31   var series = [];
  32   var x, y, point, num, den, value, stddev, variance;
  33   var mult = 100.0;
  34   var sigma = options.get("sigma");
  35   var logScale = options.get('logscale');
  36   for ( var j = 0; j < rawData.length; j++) {
  37     x = rawData[j][0];
  38     point = rawData[j][i];
  39     if (logScale && point !== null) {
  40       // On the log scale, points less than zero do not exist.
  41       // This will create a gap in the chart.
  42       if (point[0] <= 0 || point[1] <= 0) {
  43         point = null;
  44       }
  45     }
  46     // Extract to the unified data format.
  47     if (point !== null) {
  48       num = point[0];
  49       den = point[1];
  50       if (num !== null && !isNaN(num)) {
  51         value = den ? num / den : 0.0;
  52         stddev = den ? sigma * Math.sqrt(value * (1 - value) / den) : 1.0;
  53         variance = mult * stddev;
  54         y = mult * value;
  55         // preserve original values in extras for further filtering
  56         series.push([ x, y, [ y - variance, y + variance, num, den ] ]);
  57       } else {
  58         series.push([ x, num, [ num, num, num, den ] ]);
  59       }
  60     } else {
  61       series.push([ x, null, [ null, null, null, null ] ]);
  62     }
  63   }
  64   return series;
  65 };
  66
  67 /** @inheritDoc */
  68 FractionsBarsHandler.prototype.rollingAverage =
  69     function(originalData, rollPeriod, options) {
  70   rollPeriod = Math.min(rollPeriod, originalData.length);
  71   var rollingData = [];
  72   var sigma = options.get("sigma");
  73   var wilsonInterval = options.get("wilsonInterval");
  74
  75   var low, high, i, stddev;
  76   var num = 0;
  77   var den = 0; // numerator/denominator
  78   var mult = 100.0;
  79   for (i = 0; i < originalData.length; i++) {
  80     num += originalData[i][2][2];
  81     den += originalData[i][2][3];
  82     if (i - rollPeriod >= 0) {
  83       num -= originalData[i - rollPeriod][2][2];
  84       den -= originalData[i - rollPeriod][2][3];
  85     }
  86
  87     var date = originalData[i][0];
  88     var value = den ? num / den : 0.0;
  89     if (wilsonInterval) {
  90       // For more details on this confidence interval, see:
  91       // http://en.wikipedia.org/wiki/Binomial_confidence_interval
  92       if (den) {
  93         var p = value < 0 ? 0 : value, n = den;
  94         var pm = sigma * Math.sqrt(p * (1 - p) / n + sigma * sigma / (4 * n * n));
  95         var denom = 1 + sigma * sigma / den;
  96         low = (p + sigma * sigma / (2 * den) - pm) / denom;
  97         high = (p + sigma * sigma / (2 * den) + pm) / denom;
  98         rollingData[i] = [ date, p * mult,
  99             [ low * mult, high * mult ] ];
 100       } else {
 101         rollingData[i] = [ date, 0, [ 0, 0 ] ];
 102       }
 103     } else {
 104       stddev = den ? sigma * Math.sqrt(value * (1 - value) / den) : 1.0;
 105       rollingData[i] = [ date, mult * value,
 106                          [ mult * (value - stddev), mult * (value + stddev) ] ];
 107     }
 108   }
 109
 110   return rollingData;
 111 };
 112
 113 })();