# tablepress/3.4/libraries/vendor/PhpSpreadsheet/Shared/Trend/Trend.php

TablePress – Tables in WordPress made easy, version 3.4. 133 lines.

- Page: https://pluginprobe.com/plugins/tablepress/3.4/code/libraries/vendor/PhpSpreadsheet/Shared/Trend/Trend.php
- Raw: https://pluginprobe.com/plugins/tablepress/3.4/raw/libraries/vendor/PhpSpreadsheet/Shared/Trend/Trend.php
- Modified: 2025-08-26T04:06:14+00:00

Line numbers below start at 1. Link to a line or a range by appending a fragment to the
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```php
<?php

namespace TablePress\PhpOffice\PhpSpreadsheet\Shared\Trend;

use TablePress\PhpOffice\PhpSpreadsheet\Exception as SpreadsheetException;

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.
	 */
	private const TREND_TYPES = [
		self::TREND_LINEAR,
		self::TREND_LOGARITHMIC,
		self::TREND_EXPONENTIAL,
		self::TREND_POWER,
	];

	/**
	 * Names of the best-fit Trend polynomial orders.
	 *
	 * @var string[]
	 */
	private static array $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 array $trendCache = [];

	/**
	 * @param mixed[] $yValues
	 * @param mixed[] $xValues
	 */
	public static function calculate(string $trendType = self::TREND_BEST_FIT, array $yValues = [], array $xValues = [], bool $const = true): BestFit
	{
		//    Calculate number of points in each dataset
		/** @var float[] $xValues */
		$nY = count($yValues);
		/** @var float[] $xValues */
		$nX = count($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
			throw new SpreadsheetException('Trend(): Number of elements in coordinate arrays do not match.');
		}

		$key = md5($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])) {
					/** @var float[] $yValues */
					$className = '\TablePress\PhpOffice\PhpSpreadsheet\Shared\Trend\\' . $trendType . 'BestFit';
					/** @var float[] $xValues */
					self::$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);
					/** @var float[] $yValues */
					self::$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
				/** @var float[] $yValues */
				$bestFit = [];
				/** @var float[] $xValues */
				$bestFitValue = [];
				foreach (self::TREND_TYPES as $trendMethod) {
					$className = '\TablePress\PhpOffice\PhpSpreadsheet\Shared\Trend\\' . $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) {
						$order = (int) substr($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:
				throw new SpreadsheetException("Unknown trend type $trendType");
		}
	}
}

```