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   1  <?php
   2  /**
   3   * PHPExcel
   4   *
   5   * Copyright (c) 2006 - 2014 PHPExcel
   6   *
   7   * This library is free software; you can redistribute it and/or
   8   * modify it under the terms of the GNU Lesser General Public
   9   * License as published by the Free Software Foundation; either
  10   * version 2.1 of the License, or (at your option) any later version.
  11   *
  12   * This library is distributed in the hope that it will be useful,
  13   * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15   * Lesser General Public License for more details.
  16   *
  17   * You should have received a copy of the GNU Lesser General Public
  18   * License along with this library; if not, write to the Free Software
  19   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  20   *
  21   * @category   PHPExcel
  22   * @package    PHPExcel_Shared_Trend
  23   * @copyright  Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
  24   * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
  25   * @version    ##VERSION##, ##DATE##
  26   */
  27  
  28  
  29  require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/linearBestFitClass.php';
  30  require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/logarithmicBestFitClass.php';
  31  require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/exponentialBestFitClass.php';
  32  require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/powerBestFitClass.php';
  33  require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/polynomialBestFitClass.php';
  34  
  35  
  36  /**
  37   * PHPExcel_trendClass
  38   *
  39   * @category   PHPExcel
  40   * @package    PHPExcel_Shared_Trend
  41   * @copyright  Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
  42   */
  43  class trendClass
  44  {
  45      const TREND_LINEAR                = 'Linear';
  46      const TREND_LOGARITHMIC            = 'Logarithmic';
  47      const TREND_EXPONENTIAL            = 'Exponential';
  48      const TREND_POWER                = 'Power';
  49      const TREND_POLYNOMIAL_2        = 'Polynomial_2';
  50      const TREND_POLYNOMIAL_3        = 'Polynomial_3';
  51      const TREND_POLYNOMIAL_4        = 'Polynomial_4';
  52      const TREND_POLYNOMIAL_5        = 'Polynomial_5';
  53      const TREND_POLYNOMIAL_6        = 'Polynomial_6';
  54      const TREND_BEST_FIT            = 'Bestfit';
  55      const TREND_BEST_FIT_NO_POLY    = 'Bestfit_no_Polynomials';
  56  
  57      /**
  58       * Names of the best-fit trend analysis methods
  59       *
  60       * @var string[]
  61       **/
  62      private static $_trendTypes = array( self::TREND_LINEAR,
  63                                           self::TREND_LOGARITHMIC,
  64                                           self::TREND_EXPONENTIAL,
  65                                           self::TREND_POWER
  66                                         );
  67      /**
  68       * Names of the best-fit trend polynomial orders
  69       *
  70       * @var string[]
  71       **/
  72      private static $_trendTypePolyOrders = array( self::TREND_POLYNOMIAL_2,
  73                                                    self::TREND_POLYNOMIAL_3,
  74                                                    self::TREND_POLYNOMIAL_4,
  75                                                    self::TREND_POLYNOMIAL_5,
  76                                                    self::TREND_POLYNOMIAL_6
  77                                                  );
  78  
  79      /**
  80       * Cached results for each method when trying to identify which provides the best fit
  81       *
  82       * @var PHPExcel_Best_Fit[]
  83       **/
  84      private static $_trendCache = array();
  85  
  86  
  87  	public static function calculate($trendType=self::TREND_BEST_FIT, $yValues, $xValues=array(), $const=True) {
  88          //    Calculate number of points in each dataset
  89          $nY = count($yValues);
  90          $nX = count($xValues);
  91  
  92          //    Define X Values if necessary
  93          if ($nX == 0) {
  94              $xValues = range(1,$nY);
  95              $nX = $nY;
  96          } elseif ($nY != $nX) {
  97              //    Ensure both arrays of points are the same size
  98              trigger_error("trend(): Number of elements in coordinate arrays do not match.", E_USER_ERROR);
  99          }
 100  
 101          $key = md5($trendType.$const.serialize($yValues).serialize($xValues));
 102          //    Determine which trend method has been requested
 103          switch ($trendType) {
 104              //    Instantiate and return the class for the requested trend method
 105              case self::TREND_LINEAR :
 106              case self::TREND_LOGARITHMIC :
 107              case self::TREND_EXPONENTIAL :
 108              case self::TREND_POWER :
 109                  if (!isset(self::$_trendCache[$key])) {
 110                      $className = 'PHPExcel_'.$trendType.'_Best_Fit';
 111                      self::$_trendCache[$key] = new $className($yValues,$xValues,$const);
 112                  }
 113                  return self::$_trendCache[$key];
 114                  break;
 115              case self::TREND_POLYNOMIAL_2    :
 116              case self::TREND_POLYNOMIAL_3    :
 117              case self::TREND_POLYNOMIAL_4    :
 118              case self::TREND_POLYNOMIAL_5    :
 119              case self::TREND_POLYNOMIAL_6    :
 120                  if (!isset(self::$_trendCache[$key])) {
 121                      $order = substr($trendType,-1);
 122                      self::$_trendCache[$key] = new PHPExcel_Polynomial_Best_Fit($order,$yValues,$xValues,$const);
 123                  }
 124                  return self::$_trendCache[$key];
 125                  break;
 126              case self::TREND_BEST_FIT            :
 127              case self::TREND_BEST_FIT_NO_POLY    :
 128                  //    If the request is to determine the best fit regression, then we test each trend line in turn
 129                  //    Start by generating an instance of each available trend method
 130                  foreach(self::$_trendTypes as $trendMethod) {
 131                      $className = 'PHPExcel_'.$trendMethod.'BestFit';
 132                      $bestFit[$trendMethod] = new $className($yValues,$xValues,$const);
 133                      $bestFitValue[$trendMethod] = $bestFit[$trendMethod]->getGoodnessOfFit();
 134                  }
 135                  if ($trendType != self::TREND_BEST_FIT_NO_POLY) {
 136                      foreach(self::$_trendTypePolyOrders as $trendMethod) {
 137                          $order = substr($trendMethod,-1);
 138                          $bestFit[$trendMethod] = new PHPExcel_Polynomial_Best_Fit($order,$yValues,$xValues,$const);
 139                          if ($bestFit[$trendMethod]->getError()) {
 140                              unset($bestFit[$trendMethod]);
 141                          } else {
 142                              $bestFitValue[$trendMethod] = $bestFit[$trendMethod]->getGoodnessOfFit();
 143                          }
 144                      }
 145                  }
 146                  //    Determine which of our trend lines is the best fit, and then we return the instance of that trend class
 147                  arsort($bestFitValue);
 148                  $bestFitType = key($bestFitValue);
 149                  return $bestFit[$bestFitType];
 150                  break;
 151              default    :
 152                  return false;
 153          }
 154      }    //    function calculate()
 155  
 156  }    //    class trendClass