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https://issues.apache.org/jira/browse/SPARK-3573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14141063#comment-14141063
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Sandy Ryza commented on SPARK-3573:
-----------------------------------
Currently SchemaRDD does depend on Catalyst. Are you thinking we'd take that
out?
I wasn't thinking about any specific drawbacks, unless SQL might need to depend
on MLLib as well? I guess I'm thinking about it more from the perspective of
what mental model we expect users to have when dealing with Datasets.
SchemaRDD brings along baggage like LogicalPlans - do users need to understand
what that is? SQL and ML types sometimes line up, sometimes have fuzzy
relationships, and sometimes can't be translated. How does the mapping get
defined? What stops someone from annotating a String column with "numeric"?
> Dataset
> -------
>
> Key: SPARK-3573
> URL: https://issues.apache.org/jira/browse/SPARK-3573
> Project: Spark
> Issue Type: Sub-task
> Components: MLlib
> Reporter: Xiangrui Meng
> Assignee: Xiangrui Meng
> Priority: Critical
>
> This JIRA is for discussion of ML dataset, essentially a SchemaRDD with extra
> ML-specific metadata embedded in its schema.
> .Sample code
> Suppose we have training events stored on HDFS and user/ad features in Hive,
> we want to assemble features for training and then apply decision tree.
> The proposed pipeline with dataset looks like the following (need more
> refinements):
> {code}
> sqlContext.jsonFile("/path/to/training/events",
> 0.01).registerTempTable("event")
> val training = sqlContext.sql("""
> SELECT event.id AS eventId, event.userId AS userId, event.adId AS adId,
> event.action AS label,
> user.gender AS userGender, user.country AS userCountry,
> user.features AS userFeatures,
> ad.targetGender AS targetGender
> FROM event JOIN user ON event.userId = user.id JOIN ad ON event.adId =
> ad.id;""").cache()
> val indexer = new Indexer()
> val interactor = new Interactor()
> val fvAssembler = new FeatureVectorAssembler()
> val treeClassifer = new DecisionTreeClassifer()
> val paramMap = new ParamMap()
> .put(indexer.features, Map("userCountryIndex" -> "userCountry"))
> .put(indexer.sortByFrequency, true)
> .put(iteractor.features, Map("genderMatch" -> Array("userGender",
> "targetGender")))
> .put(fvAssembler.features, Map("features" -> Array("genderMatch",
> "userCountryIndex", "userFeatures")))
> .put(fvAssembler.dense, true)
> .put(treeClassifer.maxDepth, 4) // By default, classifier recognizes
> "features" and "label" columns.
> val pipeline = Pipeline.create(indexer, interactor, fvAssembler,
> treeClassifier)
> val model = pipeline.fit(raw, paramMap)
> sqlContext.jsonFile("/path/to/events", 0.01).registerTempTable("event")
> val test = sqlContext.sql("""
> SELECT event.id AS eventId, event.userId AS userId, event.adId AS adId,
> user.gender AS userGender, user.country AS userCountry,
> user.features AS userFeatures,
> ad.targetGender AS targetGender
> FROM event JOIN user ON event.userId = user.id JOIN ad ON event.adId =
> ad.id;""")
> val prediction = model.transform(test).select('eventId, 'prediction)
> {code}
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