first commit

2026-07-03 15:46:56 -04:00
commit bf8532aa1e
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+<?php
+
+namespace PhpOffice\PhpSpreadsheet\Shared\Trend;
+
+use 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 = '\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 = '\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");
+        }
+    }
+}