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
29require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/linearBestFitClass.php';
30require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/logarithmicBestFitClass.php';
31require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/exponentialBestFitClass.php';
32require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/powerBestFitClass.php';
33require_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 */
43class 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