如何将类转换为Map [X，（List [Y]，Z）]？

Question

我有以下数据的List集合：

case class Expense_detail(po_id: Long, supplier_id: String, price: String)

Expense_detail(1,"S00001","1000.0"), 
Expense_detail(2,"S00001","2000.0"), 
Expense_detail(3,"S00002","3,000.0"), 
Expense_detail(4,"S00003","4,000.0")

是否可以将其映射到下面的Map集合中：

"S00001" -> ((1,2), "3000.0")
"S00002" -> ((3), "3000.0")
"S00003" -> ((4), "4000.0")

Answer 1

是的，使用groupBy一个mapValues 。

case class ExpenseDetail(poId: Long, supplierId: String, price: String)

val details : List[ExpenseDetail] = ...

details.
 groupBy( _.supplierId ).
 mapValues( details => ( (details.map(_.poId)), details.map(_.price.toInt).sum ))

这应该工作。 我更改了名称，以纪念使用CamelCase而不是snake_case的Scala / Java最佳实践。