php多维数组把value值赋值到key,该怎么处理

php多维数组把value值赋值到key
php多维数组把value值赋值到key，改成这种效果，怎么做
"image": [
{
"local_path": "/upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg",
"picture_id": 1
},
{
"local_path": "/upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg",
"picture_id": 2
},
{
"local_path": "/upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg",
"picture_id": 3
}
]
改成：
"image": [
{
"1": "/upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg",
"picture_id": 1
},
{
"2": "/upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg",
"picture_id": 2
},
{
"3": "/upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg",
"picture_id": 3
}
]
------解决思路----------------------

$arr=array(
			array(
				'local_path' =>'aaaaa',
				'picture_id' =>1
			),
			array(
				'local_path'=>'bbbbbbb',
				'picture_id'=>2
			),
			array(
				'local_path'=>'ccccccc',
				'picture_id'=>3
			),
		);

	function change($arrr,$a=0){
		foreach($arrr as $key=>$value){
			$arr[$a][$value['picture_id']]=$value['local_path'];
			$arr[$a]['picture_id']=$value['picture_id'];
			$a++;		
		
		}
	return $arr;
	}
		
		
		$arry=change($arr);
		
		print_r($arry);
		
		
	?>	

------解决思路----------------------
你这不是 php 的数组，是 json

$s =<<< TXT
 "image": [
                {
                    "local_path": "/upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg",
                    "picture_id": 1
                },
                {
                    "local_path": "/upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg",
                    "picture_id": 2
                },
                {
                    "local_path": "/upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg",
                    "picture_id": 3
                }
            ]
TXT;
$a = json_decode('{'. $s .'}', 1);

foreach($a['image'] as &$item) {
  $item = array(
    $item['picture_id'] => $item['local_path'],
    'picture_id' => $item['picture_id']
    );
}
print_r($a);

Array
(
    [image] => Array
        (
            [0] => Array
                (
                    [1] => /upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg
                    [picture_id] => 1
                )

            [1] => Array
                (
                    [2] => /upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg
                    [picture_id] => 2
                )

            [2] => Array
                (
                    [3] => /upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg
                    [picture_id] => 3
                )

        )

)

还原回 json

echo json_encode($a, JSON_PRETTY_PRINT 
------解决思路----------------------
 JSON_UNESCAPED_SLASHES);

{
    "image": [
        {
            "1": "/upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg",
            "picture_id": 1
        },
        {
            "2": "/upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg",
            "picture_id": 2
        },
        {
            "3": "/upload/14d4aaf3c5ef5b93e6c4c7418428ea71.jpg",
            "picture_id": 3
        }
    ]
}