如何在重复值的基础上合并数组值

我的代码中有这个数组

Array
(
[0] => Array
    (
        [0] => Roof setting
        [1] => [2013-04-22,7]
    )
[1] => Array
    (
        [0] => Garbage Collection
        [1] => [2013-04-22,22]
    )
[2] => Array
    (
        [0] => Sales Payout
        [1] => [2013-04-22,10]
    )
[3] => Array
    (
        [0] => Sales Payout
        [1] => [2013-04-25,10]
    )
[4] => Array
    (
        [0] => Sales Payout
        [1] => [2013-04-25,10]
    )
[5] => Array
    (
        [0] => Fix cable car2
        [1] => [2013-04-24,77.79]
    )
[6] => Array
    (
        [0] => Fix cable car2
        [1] => [2013-04-25,77.79]
    )
)

现在我想以这样的形式得到这个数组:对于每个重复的标签，它只显示一个时间标签，并在这些标签上多次显示重复的日期。结果应该如下所示

Array
(
    'label': => Roof setting
        (
        'data:' => [2013-04-22,7]
    ),
   'label' => Garbage Collection
    (
        'data': => [2013-04-22,22]
    )
'label' => Sales Payout
    (
       'data:' => [[2013-04-22,10],[2013-04-25,10],[2013-04-25,10]]
    )

   'label' =>Fix cable car2
    (
       'data' => [[2013-04-24,77.79[,2013-04-25,77.79]]
        [1] => [2013-04-24,77.79[
    )
)