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如何在不將結果轉換爲DataFrame的情況下重命名count
操作的列?如何重命名通過Apache Spark中的GroupedDataset操作創建的新列?
case class LogRow(id: String, location: String, time: Long)
case class KeyValue(key: (String, String), value: Long)
val log = LogRow("1", "a", 1) :: LogRow("1", "a", 2) :: LogRow("1", "b", 3) :: LogRow("1", "a", 4) :: LogRow("1", "b", 5) :: LogRow("1", "b", 6) :: LogRow("1", "c", 7) :: LogRow("2", "a", 1) :: LogRow("2", "b", 2) :: LogRow("2", "b", 3) :: LogRow("2", "a", 4) :: LogRow("2", "a", 5) :: LogRow("2", "a", 6) :: LogRow("2", "c", 7) :: Nil
log.toDS().groupBy(l => {
(l.id, l.location)
}).count().toDF().toDF("key", "value").as[KeyValue].show
+-----+-----+
| key|value|
+-----+-----+
|[1,a]| 3|
|[1,b]| 3|
|[1,c]| 1|
|[2,a]| 4|
|[2,b]| 2|
|[2,c]| 1|
+-----+-----+
什麼ü通過更改列是什麼意思?改名? –
對不起,是重命名。 –