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   1  /**
   2   * jqPlot
   3   * Pure JavaScript plotting plugin using jQuery
   4   *
   5   * Version: 1.0.2
   6   * Revision: 1108
   7   *
   8   * Copyright (c) 2009-2011 Chris Leonello
   9   * jqPlot is currently available for use in all personal or commercial projects 
  10   * under both the MIT (http://www.opensource.org/licenses/mit-license.php) and GPL 
  11   * version 2.0 (http://www.gnu.org/licenses/gpl-2.0.html) licenses. This means that you can 
  12   * choose the license that best suits your project and use it accordingly. 
  13   *
  14   * Although not required, the author would appreciate an email letting him 
  15   * know of any substantial use of jqPlot.  You can reach the author at: 
  16   * chris at jqplot dot com or see http://www.jqplot.com/info.php .
  17   *
  18   * If you are feeling kind and generous, consider supporting the project by
  19   * making a donation at: http://www.jqplot.com/donate.php .
  20   *
  21   * sprintf functions contained in jqplot.sprintf.js by Ash Searle:
  22   *
  23   *     version 2007.04.27
  24   *     author Ash Searle
  25   *     http://hexmen.com/blog/2007/03/printf-sprintf/
  26   *     http://hexmen.com/js/sprintf.js
  27   *     The author (Ash Searle) has placed this code in the public domain:
  28   *     "This code is unrestricted: you are free to use it however you like."
  29   * 
  30   */
  31  (function($) {
  32      
  33      /**
  34       * Class: $.jqplot.Trendline
  35       * Plugin which will automatically compute and draw trendlines for plotted data.
  36       */
  37      $.jqplot.Trendline = function() {
  38          // Group: Properties
  39          
  40          // prop: show
  41          // Wether or not to show the trend line.
  42          this.show = $.jqplot.config.enablePlugins;
  43          // prop: color
  44          // CSS color spec for the trend line.
  45          // By default this wil be the same color as the primary line.
  46          this.color = '#666666';
  47          // prop: renderer
  48          // Renderer to use to draw the trend line.
  49          // The data series that is plotted may not be rendered as a line.
  50          // Therefore, we use our own line renderer here to draw a trend line.
  51          this.renderer = new $.jqplot.LineRenderer();
  52          // prop: rendererOptions
  53          // Options to pass to the line renderer.
  54          // By default, markers are not shown on trend lines.
  55          this.rendererOptions = {marker:{show:false}};
  56          // prop: label
  57          // Label for the trend line to use in the legend.
  58          this.label = '';
  59          // prop: type
  60          // Either 'exponential', 'exp', or 'linear'.
  61          this.type = 'linear';
  62          // prop: shadow
  63          // true or false, wether or not to show the shadow.
  64          this.shadow = true;
  65          // prop: markerRenderer
  66          // Renderer to use to draw markers on the line.
  67          // I think this is wrong.
  68          this.markerRenderer = {show:false};
  69          // prop: lineWidth
  70          // Width of the trend line.
  71          this.lineWidth = 1.5;
  72          // prop: shadowAngle
  73          // Angle of the shadow on the trend line.
  74          this.shadowAngle = 45;
  75          // prop: shadowOffset
  76          // pixel offset for each stroke of the shadow.
  77          this.shadowOffset = 1.0;
  78          // prop: shadowAlpha
  79          // Alpha transparency of the shadow.
  80          this.shadowAlpha = 0.07;
  81          // prop: shadowDepth
  82          // number of strokes to make of the shadow.
  83          this.shadowDepth = 3;
  84          this.isTrendline = true;
  85          
  86      };
  87      
  88      $.jqplot.postSeriesInitHooks.push(parseTrendLineOptions);
  89      $.jqplot.postDrawSeriesHooks.push(drawTrendline);
  90      $.jqplot.addLegendRowHooks.push(addTrendlineLegend);
  91      
  92      // called witin scope of the legend object
  93      // current series passed in
  94      // must return null or an object {label:label, color:color}
  95      function addTrendlineLegend(series) {
  96          var ret = null;
  97          if (series.trendline && series.trendline.show) {
  98              var lt = series.trendline.label.toString();
  99              if (lt) {
 100                  ret = {label:lt, color:series.trendline.color};
 101              }
 102          }
 103          return ret;
 104      }
 105  
 106      // called within scope of a series
 107      function parseTrendLineOptions (target, data, seriesDefaults, options, plot) {
 108          if (this._type && (this._type === 'line' || this._type == 'bar')) {
 109              this.trendline = new $.jqplot.Trendline();
 110              options = options || {};
 111              $.extend(true, this.trendline, {color:this.color}, seriesDefaults.trendline, options.trendline);
 112              this.trendline.renderer.init.call(this.trendline, null);
 113          }
 114      }
 115      
 116      // called within scope of series object
 117      function drawTrendline(sctx, options) {
 118          // if we have options, merge trendline options in with precedence
 119          options = $.extend(true, {}, this.trendline, options);
 120  
 121          if (this.trendline && options.show) {
 122              var fit;
 123              // this.renderer.setGridData.call(this);
 124              var data = options.data || this.data;
 125              fit = fitData(data, this.trendline.type);
 126              var gridData = options.gridData || this.renderer.makeGridData.call(this, fit.data);
 127              this.trendline.renderer.draw.call(this.trendline, sctx, gridData, {showLine:true, shadow:this.trendline.shadow});
 128          }
 129      }
 130      
 131      function regression(x, y, typ)  {
 132          var type = (typ == null) ? 'linear' : typ;
 133          var N = x.length;
 134          var slope;
 135          var intercept;  
 136          var SX = 0;
 137          var SY = 0;
 138          var SXX = 0;
 139          var SXY = 0;
 140          var SYY = 0;
 141          var Y = [];
 142          var X = [];
 143      
 144          if (type == 'linear') {
 145              X = x;
 146              Y = y;
 147          }
 148          else if (type == 'exp' || type == 'exponential') {
 149              for ( var i=0; i<y.length; i++) {
 150                  // ignore points <= 0, log undefined.
 151                  if (y[i] <= 0) {
 152                      N--;
 153                  }
 154                  else {
 155                      X.push(x[i]);
 156                      Y.push(Math.log(y[i]));
 157                  }
 158              }
 159          }
 160  
 161          for ( var i = 0; i < N; i++) {
 162              SX = SX + X[i];
 163              SY = SY + Y[i];
 164              SXY = SXY + X[i]* Y[i];
 165              SXX = SXX + X[i]* X[i];
 166              SYY = SYY + Y[i]* Y[i];
 167          }
 168  
 169          slope = (N*SXY - SX*SY)/(N*SXX - SX*SX);
 170          intercept = (SY - slope*SX)/N;
 171  
 172          return [slope, intercept];
 173      }
 174  
 175      function linearRegression(X,Y) {
 176          var ret;
 177          ret = regression(X,Y,'linear');
 178          return [ret[0],ret[1]];
 179      }
 180  
 181      function expRegression(X,Y) {
 182          var ret;
 183          var x = X;
 184          var y = Y;
 185          ret = regression(x, y,'exp');
 186          var base = Math.exp(ret[0]);
 187          var coeff = Math.exp(ret[1]);
 188          return [base, coeff];
 189      }
 190  
 191      function fitData(data, typ) {
 192          var type = (typ == null) ?  'linear' : typ;
 193          var ret;
 194          var res;
 195          var x = [];
 196          var y = [];
 197          var ypred = [];
 198          
 199          for (i=0; i<data.length; i++){
 200              if (data[i] != null && data[i][0] != null && data[i][1] != null) {
 201                  x.push(data[i][0]);
 202                  y.push(data[i][1]);
 203              }
 204          }
 205          
 206          if (type == 'linear') {
 207              ret = linearRegression(x,y);
 208              for ( var i=0; i<x.length; i++){
 209                  res = ret[0]*x[i] + ret[1];
 210                  ypred.push([x[i], res]);
 211              }
 212          }
 213          else if (type == 'exp' || type == 'exponential') {
 214              ret = expRegression(x,y);
 215              for ( var i=0; i<x.length; i++){
 216                  res = ret[1]*Math.pow(ret[0],x[i]);
 217                  ypred.push([x[i], res]);
 218              }
 219          }
 220          return {data: ypred, slope: ret[0], intercept: ret[1]};
 221      } 
 222  
 223  })(jQuery);