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<?php |
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namespace PhpOffice\PhpSpreadsheet\Shared\Trend; |
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use PhpOffice\PhpSpreadsheet\Exception as SpreadsheetException; |
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class Trend |
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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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private const TREND_TYPES = [ |
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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 array $trendTypePolynomialOrders = [ |
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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 BestFit[] |
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*/ |
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private static array $trendCache = []; |
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public static function calculate(string $trendType = self::TREND_BEST_FIT, array $yValues = [], array $xValues = [], bool $const = true): BestFit |
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{ |
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// Calculate number of points in each dataset |
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$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, $nY); |
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} elseif ($nY !== $nX) { |
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// Ensure both arrays of points are the same size |
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throw new SpreadsheetException('Trend(): Number of elements in coordinate arrays do not match.'); |
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} |
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$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 = '\PhpOffice\PhpSpreadsheet\Shared\Trend\\' . $trendType . 'BestFit'; |
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self::$trendCache[$key] = new $className($yValues, $xValues, $const); |
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} |
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return self::$trendCache[$key]; |
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case self::TREND_POLYNOMIAL_2: |
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case self::TREND_POLYNOMIAL_3: |
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case self::TREND_POLYNOMIAL_4: |
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case self::TREND_POLYNOMIAL_5: |
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case self::TREND_POLYNOMIAL_6: |
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if (!isset(self::$trendCache[$key])) { |
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$order = (int) substr($trendType, -1); |
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self::$trendCache[$key] = new PolynomialBestFit($order, $yValues, $xValues); |
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} |
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return self::$trendCache[$key]; |
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case self::TREND_BEST_FIT: |
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case self::TREND_BEST_FIT_NO_POLY: |
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// If the request is to determine the best fit regression, then we test each Trend line in turn |
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// Start by generating an instance of each available Trend method |
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$bestFit = []; |
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$bestFitValue = []; |
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foreach (self::TREND_TYPES as $trendMethod) { |
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$className = '\PhpOffice\PhpSpreadsheet\Shared\Trend\\' . $trendMethod . 'BestFit'; |
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$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 ($trendType !== self::TREND_BEST_FIT_NO_POLY) { |
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foreach (self::$trendTypePolynomialOrders as $trendMethod) { |
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$order = (int) substr($trendMethod, -1); |
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$bestFit[$trendMethod] = new PolynomialBestFit($order, $yValues, $xValues); |
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if ($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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default: |
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throw new SpreadsheetException("Unknown trend type $trendType"); |
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} |
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} |
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} |
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PHPOffice /
PhpSpreadsheet
