Cant Set :: extract（）来自数据结构

Question

我有一个看起来像下面的数据结构（只有更大，这是一个片段）。我正在尝试生成以USD格式提供的所有TechnologyIncentive金额值的总和。 Set::extract似乎是一种快速轻松地做到这一点的自然方式，但如果我能做到这一点，我会被诅咒，我认为应该这样做。我知道Set::extract只支持XPath子集，但我认为我在这种情况下工作。我试过了

Set::extract( '/' . $group . '/IncentiveAmountType[incentive_amount_type_id=USD]/../TechnologyIncentive/amount', $incentives  )
Set::extract( '/' . $group . '/{n}/IncentiveAmountType[incentive_amount_type_id=USD]/../TechnologyIncentive/amount', $incentives  )

$group值在下面的结构中评估为“Appliances”或“Building Shell”。其他组存在于数据结构的非删节版本中。我可以理解它被“建筑外壳”中的空间搞糊涂了，但它甚至不适用于“家电”。我希望我有一些错误，我已经失去了看见的能力。

我们的想法是获取一组值，然后向其中抛出array_sum()以获取每个组的总值。

感谢您的帮助。我正在努力解决的数据结构如下......

Array
(
  [Appliances] => Array
    (
      [875] => Array
        (
          [TechnologyIncentive] => Array
            (
              [id] => 875
              [incentive_id] => ccf4ceb8-6538-11e0-9cbb-00259028905a
              [technology_id] => d4da5c6a-6538-11e0-9cbb-00259028905a
              [amount] => 75.00
              [incentive_amount_type_id] => 0fb78496-6ad6-11e0-9cbb-00259028905a
              [is_active] => 1
            )

          [IncentiveAmountType] => Array
            (
              [id] => 0fb78496-6ad6-11e0-9cbb-00259028905a
              [incentive_amount_type_id] => USD
              [name] => $
              [description] => US Dollars
              [version] => 0
              [display] => 1
            )
        )

      [1103] => Array
        (
          [TechnologyIncentive] => Array
            (
                [id] => 1103
                [incentive_id] => ccf4c9b8-6538-11e0-9cbb-00259028905a
                [technology_id] => d4da5c6a-6538-11e0-9cbb-00259028905a
                [amount] => 50.00
                [incentive_amount_type_id] => 0fb78496-6ad6-11e0-9cbb-00259028905a
                [is_active] => 1
            )

          [IncentiveAmountType] => Array
            (
                [id] => 0fb78496-6ad6-11e0-9cbb-00259028905a
                [incentive_amount_type_id] => USD
                [name] => $
                [description] => US Dollars
                [version] => 0
                [display] => 1
            )
        )
    )

  [Building Shell] => Array
    (
      [1110] => Array
          (
            [TechnologyIncentive] => Array
              (
                [id] => 1110
                [incentive_id] => ccf4c9b8-6538-11e0-9cbb-00259028905a
                [technology_id] => d4d9b79c-6538-11e0-9cbb-00259028905a
                [amount] => 150.00
                [incentive_amount_type_id] => 0fb78496-6ad6-11e0-9cbb-00259028905a
                [is_active] => 1
              )

            [IncentiveAmountType] => Array
              (
                [id] => 0fb78496-6ad6-11e0-9cbb-00259028905a
                [incentive_amount_type_id] => USD
                [name] => $
                [description] => US Dollars
                [version] => 0
                [display] => 1
              )
          )

        [10941] => Array
          (
            [TechnologyIncentive] => Array
              (
                [id] => 10941
                [incentive_id] => ccf4ceb8-6538-11e0-9cbb-00259028905a
                [technology_id] => d4d9b79c-6538-11e0-9cbb-00259028905a
                [amount] => 40.00
                [incentive_amount_type_id] => 0fb783c4-6ad6-11e0-9cbb-00259028905a
                [is_active] => 1
              )

          [IncentiveAmountType] => Array
              (
                [id] => 0fb783c4-6ad6-11e0-9cbb-00259028905a
                [incentive_amount_type_id] => PERC
                [name] => %
                [description] => Percent
                [version] => 0
                [display] => 1
              )
          )
    )
)