tablepress / libraries / vendor / PhpSpreadsheet / Shared / Trend / PolynomialBestFit.php

PolynomialBestFit.php in TablePress – Tables in WordPress made easy 3.4, at libraries/vendor/PhpSpreadsheet/Shared/Trend/PolynomialBestFit.php

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1	<?php
2
3	namespace TablePress\PhpOffice\PhpSpreadsheet\Shared\Trend;
4
5	use TablePress\Matrix\Matrix;
6	use TablePress\PhpOffice\PhpSpreadsheet\Exception as SpreadsheetException;
7
8	// Phpstan and Scrutinizer seem to have legitimate complaints.
9	// $this->slope is specified where an array is expected in several places.
10	// But it seems that it should always be float.
11	// This code is probably not exercised at all in unit tests.
12	// Private bool property $implemented is set to indicate
13	// whether this implementation is correct.
14	class PolynomialBestFit extends BestFit
15	{
16	/**
17	* Algorithm type to use for best-fit
18	* (Name of this Trend class).
19	*/
20	protected string $bestFitType = 'polynomial';
21
22	/**
23	* Polynomial order.
24	*/
25	protected int $order = 0;
26
27	private bool $implemented = false;
28
29	/**
30	* Return the order of this polynomial.
31	*/
32	public function getOrder(): int
33	{
34	return $this->order;
35	}
36
37	/**
38	* Return the Y-Value for a specified value of X.
39	*
40	* @param float $xValue X-Value
41	*
42	* @return float Y-Value
43	*/
44	public function getValueOfYForX(float $xValue): float
45	{
46	$retVal = $this->getIntersect();
47	$slope = $this->getSlope();
48	foreach ($slope as $key => $value) { //* @phpstan-ignore foreach.nonIterable (this whole class is a mess)
49	/** @var float $value */
50	if ($value != 0.0) {
51	/** @var int $key */
52	$retVal += $value * $xValue ** ($key + 1);
53	}
54	}
55
56	return $retVal;
57	}
58
59	/**
60	* Return the X-Value for a specified value of Y.
61	*
62	* @param float $yValue Y-Value
63	*
64	* @return float X-Value
65	*/
66	public function getValueOfXForY(float $yValue): float
67	{
68	return ($yValue - $this->getIntersect()) / $this->getSlope();
69	}
70
71	/**
72	* Return the Equation of the best-fit line.
73	*
74	* @param int $dp Number of places of decimal precision to display
75	*/
76	public function getEquation(int $dp = 0): string
77	{
78	$slope = $this->getSlope($dp);
79	$intersect = $this->getIntersect($dp);
80
81	$equation = 'Y = ' . $intersect;
82	// Phpstan and Scrutinizer are both correct - getSlope returns float, not array.
83	foreach ($slope as $key => $value) { //* @phpstan-ignore foreach.nonIterable (this whole class is a mess)
84	/** @var float\|int $value */
85	if ($value != 0.0) {
86	$equation .= ' + ' . $value . ' * X';
87	/** @var int $key */
88	if ($key > 0) {
89	$equation .= '^' . ($key + 1);
90	}
91	}
92	}
93
94	return $equation;
95	}
96
97	/**
98	* Return the Slope of the line.
99	*
100	* @param int $dp Number of places of decimal precision to display
101	*/
102	public function getSlope(int $dp = 0): float
103	{
104	if ($dp != 0) {
105	$coefficients = [];
106	foreach ($this->slope as $coefficient) { //* @phpstan-ignore foreach.nonIterable (this whole class is a mess)
107	/** @var float\|int $coefficient */
108	$coefficients[] = round($coefficient, $dp);
109	}
110
111	return $coefficients; //* @phpstan-ignore return.type (this whole class is a mess)
112	}
113
114	return $this->slope;
115	}
116
117	/** @return array<float\|int> */
118	public function getCoefficients(int $dp = 0): array
119	{
120	return array_merge([$this->getIntersect($dp)], $this->getSlope($dp)); //* @phpstan-ignore return.type (this whole class is a mess), argument.type (ditto)
121	}
122
123	/**
124	* Execute the regression and calculate the goodness of fit for a set of X and Y data values.
125	*
126	* @param int $order Order of Polynomial for this regression
127	* @param float[] $yValues The set of Y-values for this regression
128	* @param float[] $xValues The set of X-values for this regression
129	*/
130	private function polynomialRegression(int $order, array $yValues, array $xValues): void
131	{
132	// calculate sums
133	$x_sum = array_sum($xValues);
134	$y_sum = array_sum($yValues);
135	$xx_sum = $xy_sum = $yy_sum = 0;
136	for ($i = 0; $i < $this->valueCount; ++$i) {
137	$xy_sum += $xValues[$i] * $yValues[$i];
138	$xx_sum += $xValues[$i] * $xValues[$i];
139	$yy_sum += $yValues[$i] * $yValues[$i];
140	}
141	/*
142	* This routine uses logic from the PHP port of polyfit version 0.1
143	* written by Michael Bommarito and Paul Meagher
144	*
145	* The function fits a polynomial function of order $order through
146	* a series of x-y data points using least squares.
147	*
148	*/
149	$A = [];
150	$B = [];
151	for ($i = 0; $i < $this->valueCount; ++$i) {
152	for ($j = 0; $j <= $order; ++$j) {
153	$A[$i][$j] = $xValues[$i] ** $j;
154	}
155	}
156	for ($i = 0; $i < $this->valueCount; ++$i) {
157	$B[$i] = [$yValues[$i]];
158	}
159	$matrixA = new Matrix($A);
160	$matrixB = new Matrix($B);
161	$C = $matrixA->solve($matrixB);
162
163	$coefficients = [];
164	for ($i = 0; $i < $C->rows; ++$i) {
165	$r = $C->getValue($i + 1, 1); // row and column are origin-1
166	if (!is_numeric($r) \|\| abs($r + 0) <= 10 ** (-9)) {
167	$r = 0;
168	} else {
169	$r += 0;
170	}
171	$coefficients[] = $r;
172	}
173
174	$this->intersect = (float) array_shift($coefficients);
175	$this->slope = $coefficients; //* @phpstan-ignore assign.propertyType (this whole class is a mess)
176
177	$this->calculateGoodnessOfFit($x_sum, $y_sum, $xx_sum, $yy_sum, $xy_sum, 0, 0, 0);
178	foreach ($this->xValues as $xKey => $xValue) {
179	$this->yBestFitValues[$xKey] = $this->getValueOfYForX($xValue);
180	}
181	}
182
183	/**
184	* Define the regression and calculate the goodness of fit for a set of X and Y data values.
185	*
186	* @param int $order Order of Polynomial for this regression
187	* @param float[] $yValues The set of Y-values for this regression
188	* @param float[] $xValues The set of X-values for this regression
189	*/
190	public function __construct(int $order, array $yValues, array $xValues = [])
191	{
192	if (!$this->implemented) {
193	throw new SpreadsheetException('Polynomial Best Fit not yet implemented');
194	}
195
196	parent::__construct($yValues, $xValues);
197
198	if (!$this->error) {
199	if ($order < $this->valueCount) {
200	$this->bestFitType .= '_' . $order;
201	$this->order = $order;
202	$this->polynomialRegression($order, $yValues, $xValues);
203	if (($this->getGoodnessOfFit() < 0.0) \|\| ($this->getGoodnessOfFit() > 1.0)) {
204	$this->error = true;
205	}
206	} else {
207	$this->error = true;
208	}
209	}
210	}
211	}
212