<?php
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/**
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* PHPExcel
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*
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* Copyright (c) 2006 - 2012 PHPExcel
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* @category PHPExcel
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* @package PHPExcel_Shared_Trend
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* @copyright Copyright (c) 2006 - 2012 PHPExcel (http://www.codeplex.com/PHPExcel)
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* @license http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt LGPL
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* @version 1.7.7, 2012-05-19
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*/
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require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/linearBestFitClass.php';
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require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/logarithmicBestFitClass.php';
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require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/exponentialBestFitClass.php';
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require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/powerBestFitClass.php';
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require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/polynomialBestFitClass.php';
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/**
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* PHPExcel_trendClass
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*
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* @category PHPExcel
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* @package PHPExcel_Shared_Trend
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* @copyright Copyright (c) 2006 - 2012 PHPExcel (http://www.codeplex.com/PHPExcel)
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*/
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class trendClass
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{
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const TREND_LINEAR = 'Linear';
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const TREND_LOGARITHMIC = 'Logarithmic';
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const TREND_EXPONENTIAL = 'Exponential';
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const TREND_POWER = 'Power';
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const TREND_POLYNOMIAL_2 = 'Polynomial_2';
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const TREND_POLYNOMIAL_3 = 'Polynomial_3';
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const TREND_POLYNOMIAL_4 = 'Polynomial_4';
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const TREND_POLYNOMIAL_5 = 'Polynomial_5';
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const TREND_POLYNOMIAL_6 = 'Polynomial_6';
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const TREND_BEST_FIT = 'Bestfit';
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const TREND_BEST_FIT_NO_POLY = 'Bestfit_no_Polynomials';
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/**
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* Names of the best-fit trend analysis methods
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*
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* @var string[]
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**/
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private static $_trendTypes = array( self::TREND_LINEAR,
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self::TREND_LOGARITHMIC,
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self::TREND_EXPONENTIAL,
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self::TREND_POWER
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);
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/**
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* Names of the best-fit trend polynomial orders
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*
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* @var string[]
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**/
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private static $_trendTypePolyOrders = array( self::TREND_POLYNOMIAL_2,
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self::TREND_POLYNOMIAL_3,
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self::TREND_POLYNOMIAL_4,
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self::TREND_POLYNOMIAL_5,
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self::TREND_POLYNOMIAL_6
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);
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/**
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* Cached results for each method when trying to identify which provides the best fit
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*
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* @var PHPExcel_Best_Fit[]
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**/
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private static $_trendCache = array();
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public static function calculate($trendType=self::TREND_BEST_FIT, $yValues, $xValues=array(), $const=True) {
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// Calculate number of points in each dataset
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$nY = count($yValues);
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$nX = count($xValues);
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// Define X Values if necessary
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if ($nX == 0) {
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$xValues = range(1,$nY);
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$nX = $nY;
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} elseif ($nY != $nX) {
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// Ensure both arrays of points are the same size
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trigger_error("trend(): Number of elements in coordinate arrays do not match.", E_USER_ERROR);
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}
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$key = md5($trendType.$const.serialize($yValues).serialize($xValues));
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// Determine which trend method has been requested
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switch ($trendType) {
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// Instantiate and return the class for the requested trend method
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case self::TREND_LINEAR :
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case self::TREND_LOGARITHMIC :
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case self::TREND_EXPONENTIAL :
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case self::TREND_POWER :
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if (!isset(self::$_trendCache[$key])) {
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$className = 'PHPExcel_'.$trendType.'_Best_Fit';
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self::$_trendCache[$key] = new $className($yValues,$xValues,$const);
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}
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return self::$_trendCache[$key];
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break;
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case self::TREND_POLYNOMIAL_2 :
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case self::TREND_POLYNOMIAL_3 :
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case self::TREND_POLYNOMIAL_4 :
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case self::TREND_POLYNOMIAL_5 :
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case self::TREND_POLYNOMIAL_6 :
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if (!isset(self::$_trendCache[$key])) {
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$order = substr($trendType,-1);
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self::$_trendCache[$key] = new PHPExcel_Polynomial_Best_Fit($order,$yValues,$xValues,$const);
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}
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return self::$_trendCache[$key];
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break;
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case self::TREND_BEST_FIT :
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case self::TREND_BEST_FIT_NO_POLY :
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// If the request is to determine the best fit regression, then we test each trend line in turn
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// Start by generating an instance of each available trend method
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foreach(self::$_trendTypes as $trendMethod) {
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$className = 'PHPExcel_'.$trendMethod.'BestFit';
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$bestFit[$trendMethod] = new $className($yValues,$xValues,$const);
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$bestFitValue[$trendMethod] = $bestFit[$trendMethod]->getGoodnessOfFit();
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}
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if ($trendType != self::TREND_BEST_FIT_NO_POLY) {
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foreach(self::$_trendTypePolyOrders as $trendMethod) {
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$order = substr($trendMethod,-1);
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$bestFit[$trendMethod] = new PHPExcel_Polynomial_Best_Fit($order,$yValues,$xValues,$const);
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if ($bestFit[$trendMethod]->getError()) {
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unset($bestFit[$trendMethod]);
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} else {
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$bestFitValue[$trendMethod] = $bestFit[$trendMethod]->getGoodnessOfFit();
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}
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}
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}
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// Determine which of our trend lines is the best fit, and then we return the instance of that trend class
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arsort($bestFitValue);
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$bestFitType = key($bestFitValue);
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return $bestFit[$bestFitType];
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break;
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default :
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return false;
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}
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} // function calculate()
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} // class trendClass
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