Math::euclideanDist() - Code Metrics - Inspection of "V3" - bdelespierre/php-kmeans - Measure and Improve Code Quality continuously with Scrutinizer

Passed

Pull Request — master (#34)

by Benjamin

created 2022-05-03 22:12 UTC

Math::euclideanDist() A

↳ Parent: Math

Complexity

Conditions	2
Paths	2

Size

Total Lines	9
Code Lines	4

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
cc	2
eloc	4
c	1
b	0
f	0
nc	2
nop	2
dl	0
loc	9
rs	10

<?php

namespace Kmeans;

class Math
{
    /**
     * @param array<float> $a
     * @param array<float> $b
     */
    public static function euclideanDist(array $a, array $b): float
    {
        assert(count($a) == count($b));

        for ($dist = 0, $n = 0; $n < count($a); $n++) {
for ($i=0; $i<count($array); $i++) { // calls count() on each iteration
}

// Better
for ($i=0, $c=count($array); $i<$c; $i++) { // calls count() just once
}
            $dist += pow($a[$n] - $b[$n], 2);
        }

        return sqrt($dist);
    }

    /**
     * @param array<array<float>> $points
     * @return array<float>
     */
    public static function centroid(array $points): array
    {
        $centroid = [];

        foreach ($points as $point) {
            foreach ($point as $n => $value) {
                $centroid[$n] = ($centroid[$n] ?? 0) + $value;
            }
        }

        foreach ($centroid as &$value) {
            $value /= count($points);
        }

        return $centroid;
    }

    /**
     * The standard Box–Muller transform generates values from the standard normal
     * distribution (i.e. standard normal deviates).
     *
     * @see https://en.wikipedia.org/wiki/Box%E2%80%93Muller_transform
     *
     * @return array{float, float}

     */
    public static function gaussianNoise(float $mu, float $sigma): array
    {
        static $twoPi = 2 * M_PI;

        // create two random numbers, make sure u1 is greater than epsilon
        do {
            $u1 = (float) mt_rand() / (float) mt_getrandmax();
            $u2 = (float) mt_rand() / (float) mt_getrandmax();
        } while ($u1 < PHP_FLOAT_EPSILON);

        // compute z0 and z1
        $mag = $sigma * sqrt(-2.0 * log($u1));
        $z0 = $mag * cos($twoPi * $u2) + $mu;
        $z1 = $mag * sin($twoPi * $u2) + $mu;

        return [$z0, $z1];
    }

    public static int $earthRadius = 6371009; // meters

    /**
     * Calculates the great-circle distance (in meters) between two points,
     * with the Haversine formula.
     *
     * @see https://stackoverflow.com/a/14751773/17403258
     *
     * @param array{0: float, 1: float} $from
     * @param array{0: float, 1: float} $to
     * @return float
     */
    public static function haversine($from, $to): float
    {
        return 2 * self::$earthRadius * asin(sqrt(
            pow(sin(deg2rad($to[0] - $from[0]) / 2), 2)
            + cos(deg2rad($from[0])) * cos(deg2rad($to[0]))
            * pow(sin(deg2rad($to[1] - $from[1]) / 2), 2)
        ));
    }

    /**
     * Calculates the centroid of GPS coordinates.
     *
     * @see https://stackoverflow.com/questions/6671183
     *
     * @param array<array{0: float, 1: float}> $points
     * @return array{0: float, 1: float}
     */
    public static function gpsCentroid(array $points): array
    {
        if (count($points) == 1) {
            return $points[0];
        }

        $x = $y = $z = 0;

        foreach ($points as $point) {
            $lat = deg2rad($point[0]);
            $long = deg2rad($point[1]);

            $x += cos($lat) * cos($long);
            $y += cos($lat) * sin($long);
            $z += sin($lat);
        }

        $x /= count($points);
        $y /= count($points);
        $z /= count($points);

        $hypotenuse = sqrt(pow($x, 2) + pow($y, 2));

        $long = atan2($y, $x);
        $lat = atan2($z, $hypotenuse);

        return [rad2deg($lat), rad2deg($long)];
    }
}


1			<?php
2
3			namespace Kmeans;
4
5			class Math
6			{
7			/**
8			* @param array<float> $a
9			* @param array<float> $b
10			*/
11			public static function euclideanDist(array $a, array $b): float
12			{
13			assert(count($a) == count($b));
14
15			for ($dist = 0, $n = 0; $n < count($a); $n++) {
			0 ignored issues – show Performance Best Practice introduced 2021-09-21 02:09 UTC by Report Bug Copy Issue Report It seems like you are calling the size function `count()` as part of the test condition. You might want to compute the size beforehand, and not on each iteration. If the size of the collection does not change during the iteration, it is generally a good practice to compute it beforehand, and not on each iteration: for ($i=0; $i<count($array); $i++) { // calls count() on each iteration } // Better for ($i=0, $c=count($array); $i<$c; $i++) { // calls count() just once } Loading history...
16			$dist += pow($a[$n] - $b[$n], 2);
17			}
18
19			return sqrt($dist);
20			}
21
22			/**
23			* @param array<array<float>> $points
24			* @return array<float>
25			*/
26			public static function centroid(array $points): array
27			{
28			$centroid = [];
29
30			foreach ($points as $point) {
31			foreach ($point as $n => $value) {
32			$centroid[$n] = ($centroid[$n] ?? 0) + $value;
33			}
34			}
35
36			foreach ($centroid as &$value) {
37			$value /= count($points);
38			}
39
40			return $centroid;
41			}
42
43			/**
44			* The standard Box–Muller transform generates values from the standard normal
45			* distribution (i.e. standard normal deviates).
46			*
47			* @see https://en.wikipedia.org/wiki/Box%E2%80%93Muller_transform
48			*
49			* @return array{float, float}
			0 ignored issues – show Documentation Bug introduced 2021-09-21 02:09 UTC by Report Bug Copy Issue Report The doc comment `array{float, float}` at position `2` could not be parsed: Expected ':' at position 2, but found 'float'. Loading history...
50			*/
51			public static function gaussianNoise(float $mu, float $sigma): array
52			{
53			static $twoPi = 2 * M_PI;
54
55			// create two random numbers, make sure u1 is greater than epsilon
56			do {
57			$u1 = (float) mt_rand() / (float) mt_getrandmax();
58			$u2 = (float) mt_rand() / (float) mt_getrandmax();
59			} while ($u1 < PHP_FLOAT_EPSILON);
60
61			// compute z0 and z1
62			$mag = $sigma * sqrt(-2.0 * log($u1));
63			$z0 = $mag * cos($twoPi * $u2) + $mu;
64			$z1 = $mag * sin($twoPi * $u2) + $mu;
65
66			return [$z0, $z1];
67			}
68
69			public static int $earthRadius = 6371009; // meters
70
71			/**
72			* Calculates the great-circle distance (in meters) between two points,
73			* with the Haversine formula.
74			*
75			* @see https://stackoverflow.com/a/14751773/17403258
76			*
77			* @param array{0: float, 1: float} $from
78			* @param array{0: float, 1: float} $to
79			* @return float
80			*/
81			public static function haversine($from, $to): float
82			{
83			return 2 * self::$earthRadius * asin(sqrt(
84			pow(sin(deg2rad($to[0] - $from[0]) / 2), 2)
85			+ cos(deg2rad($from[0])) * cos(deg2rad($to[0]))
86			* pow(sin(deg2rad($to[1] - $from[1]) / 2), 2)
87			));
88			}
89
90			/**
91			* Calculates the centroid of GPS coordinates.
92			*
93			* @see https://stackoverflow.com/questions/6671183
94			*
95			* @param array<array{0: float, 1: float}> $points
96			* @return array{0: float, 1: float}
97			*/
98			public static function gpsCentroid(array $points): array
99			{
100			if (count($points) == 1) {
101			return $points[0];
102			}
103
104			$x = $y = $z = 0;
105
106			foreach ($points as $point) {
107			$lat = deg2rad($point[0]);
108			$long = deg2rad($point[1]);
109
110			$x += cos($lat) * cos($long);
111			$y += cos($lat) * sin($long);
112			$z += sin($lat);
113			}
114
115			$x /= count($points);
116			$y /= count($points);
117			$z /= count($points);
118
119			$hypotenuse = sqrt(pow($x, 2) + pow($y, 2));
120
121			$long = atan2($y, $x);
122			$lat = atan2($z, $hypotenuse);
123
124			return [rad2deg($lat), rad2deg($long)];
125			}
126			}
127

bdelespierre / php-kmeans

Pull Request — master (#34)

Math::euclideanDist() A

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