Covariance::fromDataset() - Code Metrics - Inspection of "Linear algebra operations, Dimensionality reductio..." - php-ai/php-ml - Measure and Improve Code Quality continuously with Scrutinizer

Completed

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by Arkadiusz

created 2017-04-23 07:03 UTC

Covariance::fromDataset() C

↳ Parent: Covariance

Complexity

Conditions	16
Paths	9

Size

Total Lines	55
Code Lines	30

Duplication

Lines	4
Ratio	7.27 %

Importance

Changes

Metric	Value
dl	4
loc	55
rs	6.6992
c	0
b	0
f	0
cc	16
eloc	30
nc	9
nop	6

How to fix Long Method Complexity

<?php

declare(strict_types=1);

namespace Phpml\Math\Statistic;

use Phpml\Exception\InvalidArgumentException;

class Covariance
{
    /**
     * Calculates covariance from two given arrays, x and y, respectively
     *
     * @param array $x
     * @param array $y
     * @param bool $sample
     * @param float $meanX
     * @param float $meanY
     *
     * @return float
     *
     * @throws InvalidArgumentException
     */
    public static function fromXYArrays(array $x, array $y, $sample = true, float $meanX = null, float $meanY = null)
    {
        if (empty($x) || empty($y)) {
            throw InvalidArgumentException::arrayCantBeEmpty();
        }

        $n = count($x);
        if ($sample && $n === 1) {
            throw InvalidArgumentException::arraySizeToSmall(2);
        }

        if ($meanX === null) {
            $meanX = Mean::arithmetic($x);
        }

        if ($meanY === null) {
            $meanY = Mean::arithmetic($y);
        }

        $sum = 0.0;
        foreach ($x as $index => $xi) {

            $yi = $y[$index];
            $sum += ($xi - $meanX) * ($yi - $meanY);
        }

        if ($sample) {
            --$n;
        }

        return $sum / $n;
    }

    /**
     * Calculates covariance of two dimensions, i and k in the given data.
     *
     * @param array $data
     * @param int $i
     * @param int $k
     * @param type $sample
     * @param int $n
/**
 * @param array $germany
 * @param array $island
 * @param array $italy
 */
function finale($germany, $island) {
    return "2:1";
}
     * @param float $meanX
     * @param float $meanY
     */
    public static function fromDataset(array $data, int $i, int $k, $sample = true, float $meanX = null, float $meanY = null)
    {
        if (empty($data)) {
            throw InvalidArgumentException::arrayCantBeEmpty();
        }

        $n = count($data);
        if ($sample && $n === 1) {
            throw InvalidArgumentException::arraySizeToSmall(2);
        }

        if ($i < 0 || $k < 0 || $i >= $n || $k >= $n) {
            throw new \Exception("Given indices i and k do not match with the dimensionality of data");
        }

        if ($meanX === null || $meanY === null) {
            $x = array_column($data, $i);
            $y = array_column($data, $k);

            $meanX = Mean::arithmetic($x);
            $meanY = Mean::arithmetic($y);
            $sum = 0.0;
            foreach ($x as $index => $xi) {

                $yi = $y[$index];
                $sum += ($xi - $meanX) * ($yi - $meanY);
            }
        } else {
            // In the case, whole dataset given along with dimension indices, i and k,
            // we would like to avoid getting column data with array_column and operate
            // over this extra copy of column data for memory efficiency purposes.
            //
            // Instead we traverse through the whole data and get what we actually need
            // without copying the data. This way, memory use will be reduced
            // with a slight cost of CPU utilization.
            $sum = 0.0;
            foreach ($data as $row) {
                $val = [];
                foreach ($row as $index => $col) {
                    if ($index == $i) {
                        $val[0] = $col - $meanX;
                    }
                    if ($index == $k) {
                        $val[1] = $col - $meanY;
                    }
                }
                $sum += $val[0] * $val[1];
            }
        }

        if ($sample) {
            --$n;
        }

        return $sum / $n;
    }

    /**
     * Returns the covariance matrix of n-dimensional data
     *
     * @param array $data
     *
     * @return array
     */
    public static function covarianceMatrix(array $data, array $means = null)
    {
        $n = count($data[0]);

        if ($means === null) {
            $means = [];
            for ($i=0; $i < $n; $i++) {

                $means[] = Mean::arithmetic(array_column($data, $i));
            }
        }

        $cov = [];
        for ($i=0; $i < $n; $i++) {
            for ($k=0; $k < $n; $k++) {
                if ($i > $k) {
                    $cov[$i][$k] = $cov[$k][$i];
                } else {
                    $cov[$i][$k] = Covariance::fromDataset(
                        $data, $i, $k, true, $means[$i], $means[$k]);
                }
            }
        }

        return $cov;
    }
}


1		<?php
2
3		declare(strict_types=1);
4
5		namespace Phpml\Math\Statistic;
6
7		use Phpml\Exception\InvalidArgumentException;
8
9		class Covariance
10		{
11		/**
12		* Calculates covariance from two given arrays, x and y, respectively
13		*
14		* @param array $x
15		* @param array $y
16		* @param bool $sample
17		* @param float $meanX
18		* @param float $meanY
19		*
20		* @return float
21		*
22		* @throws InvalidArgumentException
23		*/
24		public static function fromXYArrays(array $x, array $y, $sample = true, float $meanX = null, float $meanY = null)
25		{
26		if (empty($x) \|\| empty($y)) {
27		throw InvalidArgumentException::arrayCantBeEmpty();
28		}
29
30		$n = count($x);
31		if ($sample && $n === 1) {
32		throw InvalidArgumentException::arraySizeToSmall(2);
33		}
34
35		if ($meanX === null) {
36		$meanX = Mean::arithmetic($x);
37		}
38
39		if ($meanY === null) {
40		$meanY = Mean::arithmetic($y);
41		}
42
43		$sum = 0.0;
44	View Code Duplication	foreach ($x as $index => $xi) {
		0 ignored issues – show Duplication introduced 2017-04-19 11:50 UTC by Report Bug Copy Issue Report This code seems to be duplicated across your project. Duplicated code is one of the most pungent code smells. If you need to duplicate the same code in three or more different places, we strongly encourage you to look into extracting the code into a single class or operation. You can also find more detailed suggestions in the “Code” section of your repository. Loading history...
45		$yi = $y[$index];
46		$sum += ($xi - $meanX) * ($yi - $meanY);
47		}
48
49		if ($sample) {
50		--$n;
51		}
52
53		return $sum / $n;
54		}
55
56		/**
57		* Calculates covariance of two dimensions, i and k in the given data.
58		*
59		* @param array $data
60		* @param int $i
61		* @param int $k
62		* @param type $sample
63		* @param int $n
		0 ignored issues – show Bug introduced 2017-04-19 11:50 UTC by Report Bug Copy Issue Report There is no parameter named `$n`. Was it maybe removed? This check looks for PHPDoc comments describing methods or function parameters that do not exist on the corresponding method or function. Consider the following example. The parameter `$italy` is not defined by the method `finale(...)`. /** * @param array $germany * @param array $island * @param array $italy */ function finale($germany, $island) { return "2:1"; } The most likely cause is that the parameter was removed, but the annotation was not. Loading history...
64		* @param float $meanX
65		* @param float $meanY
66		*/
67		public static function fromDataset(array $data, int $i, int $k, $sample = true, float $meanX = null, float $meanY = null)
68		{
69		if (empty($data)) {
70		throw InvalidArgumentException::arrayCantBeEmpty();
71		}
72
73		$n = count($data);
74		if ($sample && $n === 1) {
75		throw InvalidArgumentException::arraySizeToSmall(2);
76		}
77
78		if ($i < 0 \|\| $k < 0 \|\| $i >= $n \|\| $k >= $n) {
79		throw new \Exception("Given indices i and k do not match with the dimensionality of data");
80		}
81
82		if ($meanX === null \|\| $meanY === null) {
83		$x = array_column($data, $i);
84		$y = array_column($data, $k);
85
86		$meanX = Mean::arithmetic($x);
87		$meanY = Mean::arithmetic($y);
88		$sum = 0.0;
89	View Code Duplication	foreach ($x as $index => $xi) {
		0 ignored issues – show Duplication introduced 2017-04-19 11:50 UTC by Report Bug Copy Issue Report This code seems to be duplicated across your project. Duplicated code is one of the most pungent code smells. If you need to duplicate the same code in three or more different places, we strongly encourage you to look into extracting the code into a single class or operation. You can also find more detailed suggestions in the “Code” section of your repository. Loading history...
90		$yi = $y[$index];
91		$sum += ($xi - $meanX) * ($yi - $meanY);
92		}
93		} else {
94		// In the case, whole dataset given along with dimension indices, i and k,
95		// we would like to avoid getting column data with array_column and operate
96		// over this extra copy of column data for memory efficiency purposes.
97		//
98		// Instead we traverse through the whole data and get what we actually need
99		// without copying the data. This way, memory use will be reduced
100		// with a slight cost of CPU utilization.
101		$sum = 0.0;
102		foreach ($data as $row) {
103		$val = [];
104		foreach ($row as $index => $col) {
105		if ($index == $i) {
106		$val[0] = $col - $meanX;
107		}
108		if ($index == $k) {
109		$val[1] = $col - $meanY;
110		}
111		}
112		$sum += $val[0] * $val[1];
113		}
114		}
115
116		if ($sample) {
117		--$n;
118		}
119
120		return $sum / $n;
121		}
122
123		/**
124		* Returns the covariance matrix of n-dimensional data
125		*
126		* @param array $data
127		*
128		* @return array
129		*/
130		public static function covarianceMatrix(array $data, array $means = null)
131		{
132		$n = count($data[0]);
133
134		if ($means === null) {
135		$means = [];
136	View Code Duplication	for ($i=0; $i < $n; $i++) {
		0 ignored issues – show Duplication introduced 2017-04-19 11:50 UTC by Report Bug Copy Issue Report This code seems to be duplicated across your project. Duplicated code is one of the most pungent code smells. If you need to duplicate the same code in three or more different places, we strongly encourage you to look into extracting the code into a single class or operation. You can also find more detailed suggestions in the “Code” section of your repository. Loading history...
137		$means[] = Mean::arithmetic(array_column($data, $i));
138		}
139		}
140
141		$cov = [];
142		for ($i=0; $i < $n; $i++) {
143		for ($k=0; $k < $n; $k++) {
144		if ($i > $k) {
145		$cov[$i][$k] = $cov[$k][$i];
146		} else {
147		$cov[$i][$k] = Covariance::fromDataset(
148		$data, $i, $k, true, $means[$i], $means[$k]);
149		}
150		}
151		}
152
153		return $cov;
154		}
155		}
156

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Covariance::fromDataset() C

Complexity

Size

Duplication

Importance

How to fix Long Method Complexity

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