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Posted to reviews@spark.apache.org by GitBox <gi...@apache.org> on 2022/10/11 08:28:29 UTC
[GitHub] [spark] zhengruifeng commented on pull request #38203: [SPARK-40745][MLLIB] Reduce the shuffle size of ALS in `.mllib`
zhengruifeng commented on PR #38203:
URL: https://github.com/apache/spark/pull/38203#issuecomment-1274301748
take [`RankingMetricsExample`](https://github.com/apache/spark/blob/e3058ba17cb4512537953eb4ded884e24ee93ba2/examples/src/main/scala/org/apache/spark/examples/mllib/RankingMetricsExample.scala) for example:
```
import org.apache.spark.mllib.evaluation.{RankingMetrics, RegressionMetrics}
import org.apache.spark.mllib.recommendation.{ALS, Rating}
val ratings = spark.read.textFile("data/mllib/sample_movielens_data.txt").rdd.map { line =>
val fields = line.split("::")
Rating(fields(0).toInt, fields(1).toInt, fields(2).toDouble - 2.5)
}.cache()
// Map ratings to 1 or 0, 1 indicating a movie that should be recommended
val binarizedRatings = ratings.map(r => Rating(r.user, r.product, if (r.rating > 0) 1.0 else 0.0)).cache()
val numIterations = 1
val rank = 10
val lambda = 0.01
val model = ALS.train(ratings, rank, numIterations, lambda)
val userRecommended = model.recommendProductsForUsers(10)
userRecommended.count()
```
before:
after:
the shuffle size was reduced from `310.1 KiB` to `110.9 KiB`
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