求解面试题-将php 数组转换以下json格式

$dealer = array(
    array('dealer' => '经销商1', 'collect_num' => 1, 'likes_count' => 4),
    array('dealer' => '经销商2', 'collect_num' => 2, 'likes_count' => 5),
    array('dealer' => '经销商3', 'collect_num' => 3, 'likes_count' => 6),
);

``` {
    "dealer": ["经销商1","经销商2","经销商3"],
        "series": [
            {"platform":"collect_num", "data": [1, 2, 3]},
            {"platform":"likes_count", "data": [4, 5, 6]}           
        ]
}