<?php
namespace PhpOffice\PhpSpreadsheet\Shared\Trend;
class Trend
{
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 = [
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 = [
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 BestFit[]
*/
private static $trendCache = [];
/**
* @param string $trendType
* @param array $yValues
* @param array $xValues
* @param bool $const
*
* @return mixed
*/
public static function calculate($trendType = self::TREND_BEST_FIT, $yValues = [], $xValues = [], $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, $nY);
} elseif ($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 = '\PhpOffice\PhpSpreadsheet\Shared\Trend\\' . $trendType . 'BestFit';
self::$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])) {
$order = (int) substr($trendType, -1);
self::$trendCache[$key] = new PolynomialBestFit($order, $yValues, $xValues);
}
return self::$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
$bestFit = [];
$bestFitValue = [];
foreach (self::$trendTypes as $trendMethod) {
$className = '\PhpOffice\PhpSpreadsheet\Shared\Trend\\' . $trendType . 'BestFit';
//* @phpstan-ignore-next-line
$bestFit[$trendMethod] = new $className($yValues, $xValues, $const);
$bestFitValue[$trendMethod] = $bestFit[$trendMethod]->getGoodnessOfFit();
}
if ($trendType != self::TREND_BEST_FIT_NO_POLY) {
foreach (self::$trendTypePolynomialOrders as $trendMethod) {
$order = (int) substr($trendMethod, -1);
$bestFit[$trendMethod] = new PolynomialBestFit($order, $yValues, $xValues);
if ($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;
}
}
}
Discover the Latest in Digital Payments and NFC Technology
Dive into our blog to explore the cutting-edge trends in digital payments and NFC technology. Stay updated on the innovations that are revolutionizing transactions, boosting security, and making payments quicker and more convenient. Learn how these advancements are shaping the future of financial interactions and driving the global transition towards a cashless world.
The Rise of Contactless Payments:...
In recent years, contactless payments have surged in popularity, driven...
Enhancing Payment Security: The Role...
As digital transactions proliferate, ensuring robust payment security is more critical than ever. Two foundational...
The Future of Digital Wallets:...
Digital wallets have fundamentally transformed how we manage money, offering a streamlined, secure, and highly...
In the digital age, privacy concerns have become increasingly paramount, prompting the European Union to enact the General Data Protection Regulation (GDPR) in 2018. Among its many provisions, GDPR sets strict guidelines for the collection and processing of personal data, including the use of cookies on websites. Privacy Policy
