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  1. import java.sql.Timestamp
  2.  
  3. case class InputRow(unit:Int, eventName: String, eventTime:java.sql.Timestamp, value: Int) {
  4.   override def toString: String = s"$eventTime|$unit|$eventName|$value"
  5. }
  6.  
  7. object Main extends App {
  8.   val rows = Seq(
  9.     InputRow(2, "B", Timestamp.valueOf("2018-06-02 16:05:11"), 1),
  10.     InputRow(1, "A", Timestamp.valueOf("2018-06-02 16:05:12"), 2),
  11.     InputRow(2, "A", Timestamp.valueOf("2018-06-02 16:05:13"), 2),
  12.     InputRow(1, "A", Timestamp.valueOf("2018-06-02 16:05:14"), 3),
  13.     InputRow(2, "A", Timestamp.valueOf("2018-06-02 16:05:15"), 3)
  14.   )
  15.  
  16.   val grouped: Map[(Int, String), InputRow] = 
  17.     rows
  18.      .foldLeft(Map.empty[(Int, String), Seq[InputRow]]) { case (acc, row) =>
  19.        val key = (row.unit, row.eventName)
  20.        // Get from the accumulator the Seq that already exists or Nil if
  21.        // this key has never been seen begore
  22.        val value = acc.getOrElse(key, Nil)
  23.        // Update the accumulator
  24.        acc + (key -> (value :+ row))
  25.     }
  26.     // Get the last element from the list of rows when grouped by unit and event.
  27.     .map({case (k, v) => k -> v.last})
  28.  
  29.   grouped.values.foreach { row =>
  30.     println(row)
  31.   }
  32. }
  33.  
Success #stdin #stdout 0.45s 67456KB
comments (?)
stdin 
Standard input is empty
stdout 
2018-06-02 16:05:11.0|2|B|1
2018-06-02 16:05:14.0|1|A|3
2018-06-02 16:05:15.0|2|A|3
https://ideone.com/nLFDTu
language:
Scala (scala 2.12.8)
created:
7 years ago
visibility:
public

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