|
1
|
|
|
<?php |
|
2
|
|
|
/** |
|
3
|
|
|
* Box packing (3D bin packing, knapsack problem). |
|
4
|
|
|
* |
|
5
|
|
|
* @author Doug Wright |
|
6
|
|
|
*/ |
|
7
|
|
|
declare(strict_types=1); |
|
8
|
|
|
|
|
9
|
|
|
namespace DVDoug\BoxPacker; |
|
10
|
|
|
|
|
11
|
|
|
use Psr\Log\LoggerAwareInterface; |
|
12
|
|
|
use Psr\Log\LoggerAwareTrait; |
|
13
|
|
|
use Psr\Log\LogLevel; |
|
14
|
|
|
use Psr\Log\NullLogger; |
|
15
|
|
|
use function array_filter; |
|
16
|
|
|
use function array_merge; |
|
17
|
|
|
use function count; |
|
18
|
|
|
use function iterator_to_array; |
|
19
|
|
|
use function usort; |
|
20
|
|
|
|
|
21
|
|
|
/** |
|
22
|
|
|
* Actual packer. |
|
23
|
|
|
* |
|
24
|
|
|
* @author Doug Wright |
|
25
|
|
|
*/ |
|
26
|
|
|
class WeightRedistributor implements LoggerAwareInterface |
|
27
|
|
|
{ |
|
28
|
|
|
use LoggerAwareTrait; |
|
29
|
|
|
|
|
30
|
|
|
/** |
|
31
|
|
|
* List of box sizes available to pack items into. |
|
32
|
|
|
* |
|
33
|
|
|
* @var BoxList |
|
34
|
|
|
*/ |
|
35
|
|
|
private $boxes; |
|
36
|
|
|
|
|
37
|
|
|
/** |
|
38
|
|
|
* Constructor. |
|
39
|
|
|
* |
|
40
|
|
|
* @param BoxList $boxList |
|
41
|
|
|
*/ |
|
42
|
2 |
|
public function __construct(BoxList $boxList) |
|
43
|
|
|
{ |
|
44
|
2 |
|
$this->boxes = $boxList; |
|
45
|
2 |
|
$this->logger = new NullLogger(); |
|
46
|
2 |
|
} |
|
47
|
|
|
|
|
48
|
|
|
/** |
|
49
|
|
|
* Given a solution set of packed boxes, repack them to achieve optimum weight distribution. |
|
50
|
|
|
* |
|
51
|
|
|
* @param PackedBoxList $originalBoxes |
|
52
|
|
|
* |
|
53
|
|
|
* @return PackedBoxList |
|
54
|
|
|
*/ |
|
55
|
2 |
|
public function redistributeWeight(PackedBoxList $originalBoxes): PackedBoxList |
|
56
|
|
|
{ |
|
57
|
2 |
|
$targetWeight = $originalBoxes->getMeanWeight(); |
|
58
|
2 |
|
$this->logger->log(LogLevel::DEBUG, "repacking for weight distribution, weight variance {$originalBoxes->getWeightVariance()}, target weight {$targetWeight}"); |
|
59
|
|
|
|
|
60
|
|
|
/** @var PackedBox[] $boxes */ |
|
61
|
2 |
|
$boxes = iterator_to_array($originalBoxes); |
|
62
|
|
|
|
|
63
|
|
|
usort($boxes, function (PackedBox $boxA, PackedBox $boxB) { |
|
64
|
2 |
|
return $boxB->getWeight() <=> $boxA->getWeight(); |
|
65
|
2 |
|
}); |
|
66
|
|
|
|
|
67
|
|
|
do { |
|
68
|
2 |
|
$iterationSuccessful = false; |
|
69
|
|
|
|
|
70
|
2 |
|
foreach ($boxes as $a => &$boxA) { |
|
71
|
2 |
|
foreach ($boxes as $b => &$boxB) { |
|
72
|
2 |
|
if ($b <= $a || $boxA->getWeight() === $boxB->getWeight()) { |
|
73
|
2 |
|
continue; //no need to evaluate |
|
74
|
|
|
} |
|
75
|
|
|
|
|
76
|
2 |
|
$iterationSuccessful = $this->equaliseWeight($boxA, $boxB, $targetWeight); |
|
77
|
2 |
|
if ($iterationSuccessful) { |
|
78
|
|
|
$boxes = array_filter($boxes, function (?PackedBox $box) { //remove any now-empty boxes from the list |
|
79
|
1 |
|
return $box instanceof PackedBox; |
|
80
|
1 |
|
}); |
|
81
|
2 |
|
break 2; |
|
82
|
|
|
} |
|
83
|
|
|
} |
|
84
|
|
|
} |
|
85
|
2 |
|
} while ($iterationSuccessful); |
|
86
|
|
|
|
|
87
|
|
|
//Combine back into a single list |
|
88
|
2 |
|
$packedBoxes = new PackedBoxList(); |
|
89
|
2 |
|
$packedBoxes->insertFromArray($boxes); |
|
90
|
|
|
|
|
91
|
2 |
|
return $packedBoxes; |
|
92
|
|
|
} |
|
93
|
|
|
|
|
94
|
|
|
/** |
|
95
|
|
|
* Attempt to equalise weight distribution between 2 boxes. |
|
96
|
|
|
* |
|
97
|
|
|
* @param PackedBox $boxA |
|
98
|
|
|
* @param PackedBox $boxB |
|
99
|
|
|
* @param float $targetWeight |
|
100
|
|
|
* |
|
101
|
|
|
* @return bool was the weight rebalanced? |
|
102
|
|
|
*/ |
|
103
|
2 |
|
private function equaliseWeight(PackedBox &$boxA, PackedBox &$boxB, float $targetWeight): bool |
|
104
|
|
|
{ |
|
105
|
2 |
|
$anyIterationSuccessful = false; |
|
106
|
|
|
|
|
107
|
2 |
|
if ($boxA->getWeight() > $boxB->getWeight()) { |
|
108
|
2 |
|
$overWeightBox = $boxA; |
|
109
|
2 |
|
$underWeightBox = $boxB; |
|
110
|
|
|
} else { |
|
111
|
|
|
$overWeightBox = $boxB; |
|
112
|
|
|
$underWeightBox = $boxA; |
|
113
|
|
|
} |
|
114
|
|
|
|
|
115
|
2 |
|
$overWeightBoxItems = $overWeightBox->getItems()->asItemArray(); |
|
116
|
2 |
|
$underWeightBoxItems = $underWeightBox->getItems()->asItemArray(); |
|
117
|
|
|
|
|
118
|
2 |
|
foreach ($overWeightBoxItems as $key => $overWeightItem) { |
|
119
|
2 |
|
if ($overWeightItem->getWeight() + $boxB->getWeight() > $targetWeight) { |
|
120
|
2 |
|
continue; // moving this item would harm more than help |
|
121
|
|
|
} |
|
122
|
|
|
|
|
123
|
1 |
|
$newLighterBoxes = $this->doVolumeRepack(array_merge($underWeightBoxItems, [$overWeightItem])); |
|
124
|
1 |
|
if (count($newLighterBoxes) !== 1) { |
|
125
|
|
|
continue; //only want to move this item if it still fits in a single box |
|
126
|
|
|
} |
|
127
|
|
|
|
|
128
|
1 |
|
$underWeightBoxItems[] = $overWeightItem; |
|
129
|
|
|
|
|
130
|
1 |
|
if (count($overWeightBoxItems) === 1) { //sometimes a repack can be efficient enough to eliminate a box |
|
131
|
|
|
$boxB = $newLighterBoxes->top(); |
|
132
|
|
|
$boxA = null; |
|
133
|
|
|
|
|
134
|
|
|
return true; |
|
135
|
|
|
} else { |
|
136
|
1 |
|
unset($overWeightBoxItems[$key]); |
|
137
|
1 |
|
$newHeavierBoxes = $this->doVolumeRepack($overWeightBoxItems); |
|
138
|
1 |
|
if (count($newHeavierBoxes) !== 1) { |
|
139
|
|
|
continue; |
|
140
|
|
|
} |
|
141
|
|
|
|
|
142
|
1 |
|
if ($this->didRepackActuallyHelp($boxA, $boxB, $newHeavierBoxes->top(), $newLighterBoxes->top())) { |
|
143
|
1 |
|
$boxB = $newLighterBoxes->top(); |
|
144
|
1 |
|
$boxA = $newHeavierBoxes->top(); |
|
145
|
1 |
|
$anyIterationSuccessful = true; |
|
146
|
|
|
} |
|
147
|
|
|
} |
|
148
|
|
|
} |
|
149
|
|
|
|
|
150
|
2 |
|
return $anyIterationSuccessful; |
|
151
|
|
|
} |
|
152
|
|
|
|
|
153
|
|
|
/** |
|
154
|
|
|
* Do a volume repack of a set of items. |
|
155
|
|
|
* |
|
156
|
|
|
* @param iterable $items |
|
157
|
|
|
* |
|
158
|
|
|
* @return PackedBoxList |
|
159
|
|
|
*/ |
|
160
|
1 |
|
private function doVolumeRepack(iterable $items): PackedBoxList |
|
161
|
|
|
{ |
|
162
|
1 |
|
$packer = new Packer(); |
|
163
|
1 |
|
$packer->setBoxes($this->boxes); // use the full set of boxes to allow smaller/larger for full efficiency |
|
164
|
1 |
|
$packer->setItems($items); |
|
165
|
|
|
|
|
166
|
1 |
|
return $packer->doVolumePacking(); |
|
167
|
|
|
} |
|
168
|
|
|
|
|
169
|
|
|
/** |
|
170
|
|
|
* Not every attempted repack is actually helpful - sometimes moving an item between two otherwise identical |
|
171
|
|
|
* boxes, or sometimes the box used for the now lighter set of items actually weighs more when empty causing |
|
172
|
|
|
* an increase in total weight. |
|
173
|
|
|
* |
|
174
|
|
|
* @param PackedBox $oldBoxA |
|
175
|
|
|
* @param PackedBox $oldBoxB |
|
176
|
|
|
* @param PackedBox $newBoxA |
|
177
|
|
|
* @param PackedBox $newBoxB |
|
178
|
|
|
* |
|
179
|
|
|
* @return bool |
|
180
|
|
|
*/ |
|
181
|
1 |
|
private function didRepackActuallyHelp(PackedBox $oldBoxA, PackedBox $oldBoxB, PackedBox $newBoxA, PackedBox $newBoxB): bool |
|
182
|
|
|
{ |
|
183
|
1 |
|
$oldList = new PackedBoxList(); |
|
184
|
1 |
|
$oldList->insertFromArray([$oldBoxA, $oldBoxB]); |
|
185
|
|
|
|
|
186
|
1 |
|
$newList = new PackedBoxList(); |
|
187
|
1 |
|
$newList->insertFromArray([$newBoxA, $newBoxB]); |
|
188
|
|
|
|
|
189
|
1 |
|
return $newList->getWeightVariance() < $oldList->getWeightVariance(); |
|
190
|
|
|
} |
|
191
|
|
|
} |
|
192
|
|
|
|
dvdoug /
BoxPacker
