嵌套json示例：

{
    "accounts": {
        "1": [{
            "userId": "XXXXXXX",
            "accountId": "1",
            "externalId": "XXXXXXXXXX",
            "status": "x",
            "planId": "1",
            "investmentObjective": null,
            "vestedBalance": 50097.01,
            "payoutAction": "0",
            "payoutAmount": 0.0,
            "bacs": "xxx-xxxx-xxxx",
            "rkId": "xxx",
            "planOwnerId": "xxxx",
            "userExternalId": "xxxxxxx"
        }],
        "2": [{ 
            "userId": "XXXXXXX",
            "accountId": "2",
            "externalId": "XXXXXXXXXX",
            "status": "X",
            "planId": "1",
            "investmentObjective": "I",
            "vestedBalance": 00.0,
            "payoutAction": "0",
            "payoutAmount": 50097.01,
            "bacs": "xxx-xxxx-xxxx",
            "rkId": "xxx",
            "planOwnerId": "xxxxxx",
            "userExternalId": "xxxxxxx"

        }],
        "3": [{ 
            "userId": "XXXXXXX",
            "accountId": "3",
            "externalId": "XXXXXXXXXX",
            "status": "X",
            "planId": "1",
            "investmentObjective": "I",
            "vestedBalance": 00.0,
            "payoutAction": "0",
            "payoutAmount": 2100.00,
            "bacs": "xxx-xxxx-xxxx",
            "rkId": "xxx",
            "planOwnerId": "xxxxxx",
            "userExternalId": "xxxxxxx"

        }]
    }
}

我需要在下面的条件下计算“sumpayoutamount”
“SumPayotAmount”：investmentobjective=“i”的账户总和（PayotAmount）
上例：“sumpayoutamount”：50097.01+2100.00 for investmentobjective=“i”
如何在Pypark中实现这一点？谢谢