我们知道很多开源软件的无限分类都是采用递归的算法，但是我们知道递归即浪费时间，又浪费空间（内存），
上次我也分享了个我自己原创的无限分类生成树的方法，一热心php高手网友给我提出了宝贵的建议，我测试了一下，这段代码的时间非常之短参考： http://www.oschina.net/code/snippet_98719_11296，我再次整理了一下，发现数据库查询出数据之后，我们就已经定好了键值，因而实践中，我们一般会在model中查询出格式化成主键值对应数据的形式，因而我们可以直接用这样的数据，就少了一层循环。代码也非常简洁。
原来的代码：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
|
function genTree($items,$id='id',$pid='pid',$son = 'children'){
$tree = array(); //格式化的树
$tmpMap = array(); //临时扁平数据
foreach ($items as $item) {
$tmpMap[$item[$id]] = $item;
}
foreach ($items as $item) {
if (isset($tmpMap[$item[$pid]])) {
$tmpMap[$item[$pid]][$son][] = &$tmpMap[$item[$id]];
} else {
$tree[] = &$tmpMap[$item[$id]];
}
}
unset($tmpMap);
return $tree;
}
$items1 = array(
array('id' => 1, 'pid' => 0, 'name' => '一级11' ),
array('id' => 11, 'pid' => 0, 'name' => '一级12' ),
array('id' => 2, 'pid' => 1, 'name' => '二级21' ),
array('id' => 10, 'pid' => 11, 'name' => '二级22' ),
array('id' => 3, 'pid' => 1, 'name' => '二级23' ),
array('id' => 12, 'pid' => 11, 'name' => '二级24' ),
array('id' => 9, 'pid' => 1, 'name' => '二级25' ),
array('id' => 14, 'pid' => 1, 'name' => '二级26' ),
array('id' => 4, 'pid' => 9, 'name' => '三级31' ),
array('id' => 6, 'pid' => 9, 'name' => '三级32' ),
array('id' => 7, 'pid' => 4, 'name' => '四级41' ),
array('id' => 8, 'pid' => 4, 'name' => '四级42' ),
array('id' => 5, 'pid' => 4, 'name' => '四级43' ),
array('id' => 13, 'pid' => 4, 'name' => '四级44' ),
array('id' => 15, 'pid' => 8, 'name' => '五级51' ),
array('id' => 16, 'pid' => 8, 'name' => '五级52' ),
array('id' => 17, 'pid' => 8, 'name' => '五级53' ),
array('id' => 18, 'pid' => 16, 'name' => '六级64' ),
);
var_dump(genTree($items1));
|
以下是补充：
|
1
2
3
4
5
6
7
8
9
10
|
/**
* 此方法由@Tonton 提供
* http://my.oschina.net/u/918697
* @date 2012-12-12
*/
function genTree5($items) {
foreach ($items as $item)
$items[$item['pid']]['son'][$item['id']] = &$items[$item['id']];
return isset($items[0]['son']) ? $items[0]['son'] : array();
}
|
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
|
/**
* 将数据格式化成树形结构
* @author Xuefen.Tong
* @param array $items
* @return array
*/
function genTree9($items) {
$tree = array(); //格式化好的树
foreach ($items as $item)
if (isset($items[$item['pid']]))
$items[$item['pid']]['son'][] = &$items[$item['id']];
else
$tree[] = &$items[$item['id']];
return $tree;
}
$items = array(
1 => array('id' => 1, 'pid' => 0, 'name' => '江西省'),
2 => array('id' => 2, 'pid' => 0, 'name' => '黑龙江省'),
3 => array('id' => 3, 'pid' => 1, 'name' => '南昌市'),
4 => array('id' => 4, 'pid' => 2, 'name' => '哈尔滨市'),
5 => array('id' => 5, 'pid' => 2, 'name' => '鸡西市'),
6 => array('id' => 6, 'pid' => 4, 'name' => '香坊区'),
7 => array('id' => 7, 'pid' => 4, 'name' => '南岗区'),
8 => array('id' => 8, 'pid' => 6, 'name' => '和兴路'),
9 => array('id' => 9, 'pid' => 7, 'name' => '西大直街'),
10 => array('id' => 10, 'pid' => 8, 'name' => '东北林业大学'),
11 => array('id' => 11, 'pid' => 9, 'name' => '哈尔滨工业大学'),
12 => array('id' => 12, 'pid' => 8, 'name' => '哈尔滨师范大学'),
13 => array('id' => 13, 'pid' => 1, 'name' => '赣州市'),
14 => array('id' => 14, 'pid' => 13, 'name' => '赣县'),
15 => array('id' => 15, 'pid' => 13, 'name' => '于都县'),
16 => array('id' => 16, 'pid' => 14, 'name' => '茅店镇'),
17 => array('id' => 17, 'pid' => 14, 'name' => '大田乡'),
18 => array('id' => 18, 'pid' => 16, 'name' => '义源村'),
19 => array('id' => 19, 'pid' => 16, 'name' => '上坝村'),
);
print_r(genTree5($items));
print_r(genTree9($items));
//后者输出格式，前者类似，只是数组键值不一样，不过不影响数据结构
/*
Array
(
[0] => Array
(
[id] => 1
[pid] => 0
[name] => 江西省
[son] => Array
(
[0] => Array
(
[id] => 3
[pid] => 1
[name] => 南昌市
)
[1] => Array
(
[id] => 13
[pid] => 1
[name] => 赣州市
[son] => Array
(
[0] => Array
(
[id] => 14
[pid] => 13
[name] => 赣县
[son] => Array
(
[0] => Array
(
[id] => 16
[pid] => 14
[name] => 茅店镇
[son] => Array
(
[0] => Array
(
[id] => 18
[pid] => 16
[name] => 义源村
)
[1] => Array
(
[id] => 19
[pid] => 16
[name] => 上坝村
)
)
)
[1] => Array
(
[id] => 17
[pid] => 14
[name] => 大田乡
)
)
)
[1] => Array
(
[id] => 15
[pid] => 13
[name] => 于都县
)
)
)
)
)
[1] => Array
(
[id] => 2
[pid] => 0
[name] => 黑龙江省
[son] => Array
(
[0] => Array
(
[id] => 4
[pid] => 2
[name] => 哈尔滨市
[son] => Array
(
[0] => Array
(
[id] => 6
[pid] => 4
[name] => 香坊区
[son] => Array
(
[0] => Array
(
[id] => 8
[pid] => 6
[name] => 和兴路
[son] => Array
(
[0] => Array
(
[id] => 10
[pid] => 8
[name] =>
东北林业大学
)
[1] => Array
(
[id] => 12
[pid] => 8
[name] =>
哈尔滨师范大学
)
)
)
)
)
[1] => Array
(
[id] => 7
[pid] => 4
[name] => 南岗区
[son] => Array
(
[0] => Array
(
[id] => 9
[pid] => 7
[name] => 西大直街
[son] => Array
(
[0] => Array
(
[id] => 11
[pid] => 9
[name] =>
哈尔滨工业大学
)
)
)
)
)
)
)
[1] => Array
(
[id] => 5
[pid] => 2
[name] => 鸡西市
)
)
)
)*/
|
极其简单有效！！！非常受用！