[GitHub] [spark] zhengruifeng commented on a change in pull request #30468: [SPARK-33518][ML][WIP] Improve performance of ML ALS recommendForAll by GEMV

[GitBox <gi...@apache.org>]

zhengruifeng commented on a change in pull request #30468:
URL: https://github.com/apache/spark/pull/30468#discussion_r529219939



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File path: mllib/src/main/scala/org/apache/spark/ml/recommendation/TopByKeyAggregator.scala
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@@ -57,3 +57,57 @@ private[recommendation] class TopByKeyAggregator[K1: TypeTag, K2: TypeTag, V: Ty
 
   override def outputEncoder: Encoder[Array[(K2, V)]] = ExpressionEncoder[Array[(K2, V)]]()
 }
+
+
+/**
+ * Works on rows of the form (ScrId, DstIds, Scores).
+ * Finds the top `num` DstIds and Scores.
+ */
+private[recommendation] class TopKArrayAggregator(num: Int)

Review comment:
       since I just find that aggregating on array bring little improvement, so I will remove this class




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