## groupBy
根據指定的分組函數對值進行分組
例子：
~~~
$members=[
['id'=>1,'name'=>'小明','sex'=>'男','age'=>18,'register_time'=>'2017-04-01 08:30:01'],
['id'=>2,'name'=>'小紅','sex'=>'女','age'=>18,'register_time'=>'2017-04-02 12:21:32'],
['id'=>3,'name'=>'小剛','sex'=>'男','age'=>16,'register_time'=>'2017-04-05 09:10:13'],
['id'=>4,'name'=>'小麗','sex'=>'女','age'=>19,'register_time'=>'2017-04-05 12:05:27'],
['id'=>5,'name'=>'小壯','sex'=>'男','age'=>21,'register_time'=>'2017-04-08 15:41:59'],
['id'=>6,'name'=>'小東','sex'=>'男','age'=>21,'register_time'=>'2017-04-01 08:30:01'],
];
$dataSource=Traversable::from($members);
$result=$dataSource->groupBy(function($m){
return $m['age']; //按照age分組，age相同的分到同一組。
});
foreach ($result as $s){
dump($s);
}
~~~
打印結果：
~~~
Traversable {#45 ▼
#scheme: GeneratorScheme {#17}
#source: Traversable {#14 ?}
#elements: OrderedMap {#34 ▼
#keys: array:2 [?]
#values: array:2 [▼
0 => &2 array:5 [▼
"id" => 1
"name" => "小明"
"sex" => "男"
"age" => 18
"register_time" => "2017-04-01 08:30:01"
]
1 => &3 array:5 [▼
"id" => 2
"name" => "小紅"
"sex" => "女"
"age" => 18
"register_time" => "2017-04-02 12:21:32"
]
]
#keyIdentityPositionMap: array:2 [?]
#length: 2
#largestIntKey: 1
}
}
Traversable {#49 ▼
#scheme: GeneratorScheme {#17}
#source: Traversable {#14 ?}
#elements: OrderedMap {#36 ▼
#keys: array:1 [?]
#values: array:1 [▼
0 => &4 array:5 [▼
"id" => 3
"name" => "小剛"
"sex" => "男"
"age" => 16
"register_time" => "2017-04-05 09:10:13"
]
]
#keyIdentityPositionMap: array:1 [?]
#length: 1
#largestIntKey: 2
}
}
Traversable {#45 ▼
#scheme: GeneratorScheme {#17}
#source: Traversable {#14 ?}
#elements: OrderedMap {#37 ▼
#keys: array:1 [?]
#values: array:1 [▼
0 => &5 array:5 [▼
"id" => 4
"name" => "小麗"
"sex" => "女"
"age" => 19
"register_time" => "2017-04-05 12:05:27"
]
]
#keyIdentityPositionMap: array:1 [?]
#length: 1
#largestIntKey: 3
}
}
Traversable {#49 ▼
#scheme: GeneratorScheme {#17}
#source: Traversable {#14 ?}
#elements: OrderedMap {#38 ▼
#keys: array:2 [?]
#values: array:2 [▼
0 => &6 array:5 [▼
"id" => 5
"name" => "小壯"
"sex" => "男"
"age" => 21
"register_time" => "2017-04-08 15:41:59"
]
1 => &7 array:5 [▼
"id" => 6
"name" => "小東"
"sex" => "男"
"age" => 21
"register_time" => "2017-04-01 08:30:01"
]
]
#keyIdentityPositionMap: array:2 [?]
#length: 2
#largestIntKey: 5
}
}
~~~
