src/extras/rebase.js

   1 /**
   2  * @license
   3  * Copyright 2015 Petr Shevtsov (petr.shevtsov@gmail.com)
   4  * MIT-licensed (http://opensource.org/licenses/MIT)
   5  *
   6  * Rebase plugin
   7  *
   8  * On pan/zoom event, each series will rebase to a specified value (e.g. 100) at the
   9  * start of the displayed period.
  10  *
  11  * See http://stats.oecd.org/glossary/detail.asp?ID=2249
  12  *
  13  * Options:
  14  *  Value to rebase. Must be either Number or 'percent' or null.
  15  *
  16  * See tests/straw-broom.html for demo.
  17  */
  18
  19 /*global Dygraph:false */
  20
  21 (function() {
  22   "use strict";
  23
  24   Dygraph.DataHandlers.RebaseHandler = function(baseOpt) {
  25     this.baseOpt = baseOpt;
  26   };
  27
  28   var RebaseHandler =  Dygraph.DataHandlers.RebaseHandler;
  29   RebaseHandler.prototype = new Dygraph.DataHandlers.DefaultHandler();
  30
  31   RebaseHandler.rebase = function(value, initial, base) {
  32     if (base === "percent") {
  33       return (value / initial - 1) * 100;
  34     }
  35     return value * base / initial;
  36   };
  37
  38   RebaseHandler.prototype.getExtremeYValues = function(series, dateWindow, options) {
  39     var minY = null, maxY = null, y;
  40     var firstIdx = 0, lastIdx = series.length - 1;
  41     var initial = series[firstIdx][1];
  42
  43     for (var j = firstIdx; j <= lastIdx; j++) {
  44       if (j === firstIdx) {
  45         y = (this.baseOpt === "percent") ? 0 : this.baseOpt;
  46       } else {
  47         y = RebaseHandler.rebase(series[j][1], initial, this.baseOpt);
  48       }
  49       if (y === null || isNaN(y))
  50         continue;
  51       if (maxY === null || y > maxY) {
  52         maxY = y;
  53       }
  54       if (minY === null || y < minY) {
  55         minY = y;
  56       }
  57     }
  58     return [ minY, maxY ];
  59   };
  60
  61   RebaseHandler.prototype.seriesToPoints = function(series, setName, boundaryIdStart){
  62     var points = [];
  63     var firstIdx = 0;
  64     var lastIdx = series.length - 1;
  65     var initial = series[firstIdx][1]; // TODO: check for null
  66     for (var i = 0; i <= lastIdx; ++i) {
  67       var item = series[i];
  68       var yraw = item[1];
  69       var yval = yraw === null ? null : Dygraph.DataHandler.parseFloat(yraw);
  70       if (yval !== null) {
  71         if (i === firstIdx) {
  72           yval = (this.baseOpt === "percent") ? 0 : this.baseOpt;
  73         } else {
  74           yval = RebaseHandler.rebase(yval, initial, this.baseOpt);
  75         }
  76       }
  77       var point = {
  78         x: NaN,
  79         y: NaN,
  80         xval: Dygraph.DataHandler.parseFloat(item[0]),
  81         yval: yval,
  82         name: setName,
  83         idx: i + boundaryIdStart
  84       };
  85       points.push(point);
  86     }
  87     this.onPointsCreated_(series, points);
  88     return points;
  89   };
  90
  91   Dygraph.Plugins.Rebase = (function() {
  92     var rebase = function(baseOpt) {
  93       var isNum = function(v) {
  94         return !isNaN(v) && (typeof v === 'number' || {}.toString.call(v) === '[object Number]');
  95       };
  96       if (baseOpt === "percent" || isNum(baseOpt)) {
  97         this.baseOpt_ = baseOpt;
  98       } else {
  99         this.baseOpt_ = null;
 100       }
 101     };
 102
 103     rebase.prototype.toString = function() {
 104       return "Rebase Plugin";
 105     };
 106
 107     rebase.prototype.activate = function(g) {
 108       if (this.baseOpt_ === null) {
 109         return;
 110       }
 111       return {
 112         predraw: this.predraw
 113       };
 114     };
 115
 116     rebase.prototype.predraw = function(e) {
 117       var g = e.dygraph;
 118
 119       if (this.baseOpt_ === "percent") {
 120         g.updateOptions({
 121           axes: {
 122             y: {
 123               axisLabelFormatter: function(y) {
 124                 return y + '%';
 125               },
 126               valueFormatter: function(y) {
 127                 return Math.round(y * 100) / 100 + '%';
 128               }
 129             }
 130           }
 131         }, true);
 132       }
 133
 134       g.dataHandler_ = new Dygraph.DataHandlers.RebaseHandler(this.baseOpt_);
 135     };
 136
 137     return rebase;
 138   })();
 139 })();