演算法 - php如何將一個陣列重複的元素合併到一個新的陣列？

假設目前陣列為
array(
0=>array('key1'=>'value1' , 'key2'=>'value2'),
1=>array('key1'=>'value1value1
' , 'key2'=>'value3'),
2=>array('key1'=>'value2' , 'key2'=>'value4'),
...
999=>array('key1' =>'value2' , 'key2'=>'value5')
)
如何將這個array中key1的value 相同的情況下將key2的value合併成一個新的數組。求寫一個方法將原始數組轉換問如下數組
array(
0=>array('value1'=>array('value2','value3')),
1=>array('value2'=>array( 'value4','value5')),
...

假設目前陣列為
array(0=>array('key1'=>'value1
' , 'key2'=>'value2'),1=>array('key1'=>'value1
value1
' , 'key2'=>'value3'),
2=>array('key1'=>'value2' , 'key2'=>'value4'),
...
999=>array('key1' =>'value2' , 'key2'=>'value5')
)
如何將這個array中key1的value 相同的情況下將key2的value合併成一個新的數組。求寫一個方法將原始數組轉換問如下數組
array(
0=>array('value1'=>array('value2','value3')),
1=>array('value2'=>array( 'value4','value5')),

)

題主，是無論

是否有重複都獨立嗎？下面是這樣的做法

<code>$arr = array(
    0=>array('key1'=>'value1' , 'key2'=>'value2'),
    1=>array('key1'=>'value1' , 'key2'=>'value3'),
    2=>array('key1'=>'value2' , 'key2'=>'value4'),
    999=>array('key1'=>'value2' , 'key2'=>'value5')
);

$result = array();
foreach ($arr as $data) {
    isset($result[$data['key1']]) || $result[$data['key1']] = array();
    $result[$data['key1']][] = $data['key2'];
}
print_r($result);

//输出如下
Array
(
    [value1] => Array
        (
            [0] => value2
            [1] => value3
        )

    [value2] => Array
        (
            [0] => value4
            [1] => value5
        )
        
)</code>