我尝试只提取routriarys.element和validatingAirlineCodes，然后在Pyspark中形成只包含这两个字段的json

|-- id: string (nullable = true)
 |-- instantTicketingRequired: boolean (nullable = true)
 |-- itineraries: array (nullable = true)
 |    |-- element: map (containsNull = true)
 |    |    |-- key: string
 |    |    |-- value: string (valueContainsNull = true)
 |-- lastTicketingDate: string (nullable = true)
 |-- nonHomogeneous: boolean (nullable = true)
 |-- numberOfBookableSeats: long (nullable = true)
 |-- oneWay: boolean (nullable = true)
 |-- price: map (nullable = true)
 |    |-- key: string
 |    |-- value: string (valueContainsNull = true)
 |-- pricingOptions: map (nullable = true)
 |    |-- key: string
 |    |-- value: array (valueContainsNull = true)
 |    |    |-- element: string (containsNull = true)
 |-- source: string (nullable = true)
 |-- travelerPricings: array (nullable = true)
 |    |-- element: map (containsNull = true)
 |    |    |-- key: string
 |    |    |-- value: string (valueContainsNull = true)
 |-- type: string (nullable = true)
 |-- validatingAirlineCodes: array (nullable = true)
 |    |-- element: string (containsNull = true)

我尝试使用df.select（），但无法选择所需的字段。我该怎么办？