1<?php
2
3/**
4 * This file is part of PHP K-Means
5 *
6 * Copyright (c) 2014 Benjamin Delespierre
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this software and associated documentation files (the "Software"), to deal
10 * in the Software without restriction, including without limitation the rights
11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 * copies of the Software, and to permit persons to whom the Software is furnished
13 * to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in all
16 * copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
24 * THE SOFTWARE.
25 */
26
27namespace KMeans;
28
29class Cluster extends Point implements \IteratorAggregate, \Countable
30{
31    public const INIT_RANDOM = 1;
32    public const INIT_KMEANS_PLUS_PLUS = 2;
33
34    protected $space;
35    protected $points;
36
37    public function __construct(Space $space, array $coordinates)
38    {
39        parent::__construct($space, $coordinates);
40        $this->points = new \SplObjectStorage();
41    }
42
43    public function toArray(): array
44    {
45        $points = [];
46        foreach ($this->points as $point) {
47            $points[] = $point->toArray();
48        }
49
50        return [
51            'centroid' => parent::toArray(),
52            'points'   => $points,
53        ];
54    }
55
56    public function attach(Point $point): Point
57    {
58        if ($point instanceof self) {
59            throw new \LogicException("cannot attach a cluster to another");
60        }
61
62        $this->points->attach($point);
63        return $point;
64    }
65
66    public function detach(Point $point): Point
67    {
68        $this->points->detach($point);
69        return $point;
70    }
71
72    public function attachAll(\SplObjectStorage $points): void
73    {
74        $this->points->addAll($points);
75    }
76
77    public function detachAll(\SplObjectStorage $points): void
78    {
79        $this->points->removeAll($points);
80    }
81
82    public function updateCentroid(): void
83    {
84        if (!$count = count($this->points)) {
85            return;
86        }
87
88        $centroid = $this->space->newPoint(array_fill(0, $this->dimention, 0));
89
90        foreach ($this->points as $point) {
91            for ($n = 0; $n < $this->dimention; $n++) {
92                $centroid->coordinates[$n] += $point->coordinates[$n];
93            }
94        }
95
96        for ($n = 0; $n < $this->dimention; $n++) {
97            $this->coordinates[$n] = $centroid->coordinates[$n] / $count;
98        }
99    }
100
101    public function getIterator(): \Iterator
102    {
103        return $this->points;
104    }
105
106    public function count(): int
107    {
108        return count($this->points);
109    }
110}
111