case class Step (Id : Long,
stepNum : Long,
stepId : Int,
stepTime: java.sql.Timestamp
)
我有一个数据集[Step],我想在" Id"上执行groupBy操作。山坳。 我的输出应该看起来像Dataset [(Long,List [Step])]。我该怎么做?
让变量" inquiryStepMap"是数据集[步骤]类型然后我们可以使用RDD执行此操作
val inquiryStepGrouped: RDD[(Long, Iterable[Step])] = inquiryStepMap.rdd.groupBy(x => x.Id)
答案 0 :(得分:2)
您似乎需要groupByKey
:
样品:
import java.sql.Timestamp
val t = new Timestamp(2017, 5, 1, 0, 0, 0, 0)
val ds = Seq(Step(1L, 21L, 1, t), Step(1L, 20L, 2, t), Step(2L, 10L, 3, t)).toDS()
groupByKey
然后mapGroups
:
ds.groupByKey(_.Id).mapGroups((Id, Vals) => (Id, Vals.toList))
// res18: org.apache.spark.sql.Dataset[(Long, List[Step])] = [_1: bigint, _2: array<struct<Id:bigint,stepNum:bigint,stepId:int,stepTime:timestamp>>]
结果如下:
ds.groupByKey(_.Id).mapGroups((Id, Vals) => (Id, Vals.toList)).show()
+---+--------------------+
| _1| _2|
+---+--------------------+
| 1|[[1,21,1,3917-06-...|
| 2|[[2,10,3,3917-06-...|
+---+--------------------+