trendClass.php
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<?php
require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/linearBestFitClass.php';
require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/logarithmicBestFitClass.php';
require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/exponentialBestFitClass.php';
require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/powerBestFitClass.php';
require_once PHPEXCEL_ROOT . 'PHPExcel/Shared/trend/polynomialBestFitClass.php';
/**
* PHPExcel_trendClass
*
* Copyright (c) 2006 - 2015 PHPExcel
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* @category PHPExcel
* @package PHPExcel_Shared_Trend
* @copyright Copyright (c) 2006 - 2015 PHPExcel (http://www.codeplex.com/PHPExcel)
* @license http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt LGPL
* @version ##VERSION##, ##DATE##
*/
class trendClass
{
const TREND_LINEAR = 'Linear';
const TREND_LOGARITHMIC = 'Logarithmic';
const TREND_EXPONENTIAL = 'Exponential';
const TREND_POWER = 'Power';
const TREND_POLYNOMIAL_2 = 'Polynomial_2';
const TREND_POLYNOMIAL_3 = 'Polynomial_3';
const TREND_POLYNOMIAL_4 = 'Polynomial_4';
const TREND_POLYNOMIAL_5 = 'Polynomial_5';
const TREND_POLYNOMIAL_6 = 'Polynomial_6';
const TREND_BEST_FIT = 'Bestfit';
const TREND_BEST_FIT_NO_POLY = 'Bestfit_no_Polynomials';
/**
* Names of the best-fit trend analysis methods
*
* @var string[]
**/
private static $trendTypes = array(
self::TREND_LINEAR,
self::TREND_LOGARITHMIC,
self::TREND_EXPONENTIAL,
self::TREND_POWER
);
/**
* Names of the best-fit trend polynomial orders
*
* @var string[]
**/
private static $trendTypePolynomialOrders = array(
self::TREND_POLYNOMIAL_2,
self::TREND_POLYNOMIAL_3,
self::TREND_POLYNOMIAL_4,
self::TREND_POLYNOMIAL_5,
self::TREND_POLYNOMIAL_6
);
/**
* Cached results for each method when trying to identify which provides the best fit
*
* @var PHPExcel_Best_Fit[]
**/
private static $trendCache = array();
public static function calculate($trendType = self::TREND_BEST_FIT, $yValues, $xValues = array(), $const = true)
{
// Calculate number of points in each dataset
$nY = count($yValues);
$nX = count($xValues);
// Define X Values if necessary
if ($nX == 0) {
$xValues = range(1, $nY);
$nX = $nY;
} elseif ($nY != $nX) {
// Ensure both arrays of points are the same size
trigger_error("trend(): Number of elements in coordinate arrays do not match.", E_USER_ERROR);
}
$key = md5($trendType.$const.serialize($yValues).serialize($xValues));
// Determine which trend method has been requested
switch ($trendType) {
// Instantiate and return the class for the requested trend method
case self::TREND_LINEAR:
case self::TREND_LOGARITHMIC:
case self::TREND_EXPONENTIAL:
case self::TREND_POWER:
if (!isset(self::$trendCache[$key])) {
$className = 'PHPExcel_'.$trendType.'_Best_Fit';
self::$trendCache[$key] = new $className($yValues, $xValues, $const);
}
return self::$trendCache[$key];
case self::TREND_POLYNOMIAL_2:
case self::TREND_POLYNOMIAL_3:
case self::TREND_POLYNOMIAL_4:
case self::TREND_POLYNOMIAL_5:
case self::TREND_POLYNOMIAL_6:
if (!isset(self::$trendCache[$key])) {
$order = substr($trendType, -1);
self::$trendCache[$key] = new PHPExcel_Polynomial_Best_Fit($order, $yValues, $xValues, $const);
}
return self::$trendCache[$key];
case self::TREND_BEST_FIT:
case self::TREND_BEST_FIT_NO_POLY:
// If the request is to determine the best fit regression, then we test each trend line in turn
// Start by generating an instance of each available trend method
foreach (self::$trendTypes as $trendMethod) {
$className = 'PHPExcel_'.$trendMethod.'BestFit';
$bestFit[$trendMethod] = new $className($yValues, $xValues, $const);
$bestFitValue[$trendMethod] = $bestFit[$trendMethod]->getGoodnessOfFit();
}
if ($trendType != self::TREND_BEST_FIT_NO_POLY) {
foreach (self::$trendTypePolynomialOrders as $trendMethod) {
$order = substr($trendMethod, -1);
$bestFit[$trendMethod] = new PHPExcel_Polynomial_Best_Fit($order, $yValues, $xValues, $const);
if ($bestFit[$trendMethod]->getError()) {
unset($bestFit[$trendMethod]);
} else {
$bestFitValue[$trendMethod] = $bestFit[$trendMethod]->getGoodnessOfFit();
}
}
}
// Determine which of our trend lines is the best fit, and then we return the instance of that trend class
arsort($bestFitValue);
$bestFitType = key($bestFitValue);
return $bestFit[$bestFitType];
default:
return false;
}
}
}