[SPARK-19339] StatFunctions.multipleApproxQuantiles can give NoSuchElementException: next on empty iterator

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Duplicate
• Affects Version/s: 2.0.2, 2.1.0
• Component/s: MLlib
• Assignee: Unassigned
• Reporter: Barry Becker
• Created: 23/Jan/17 22:44
• Updated: 03/Mar/17 10:50
• Resolved: 03/Mar/17 10:50

Description

This problem is easy to reproduce by running StatFunctions.multipleApproxQuantiles on an empty dataset, but I think it can occur in other cases, like if the column is all null or all one value.
I have unit tests that can hit it in several different cases.

The fix that I have introduced locally is to return

 if (sampled.length == 0) 0 else sampled.last.value

instead of

sampled.last.value

at the end of QuantileSummaries.query.
Below is the exception:

next on empty iterator
java.util.NoSuchElementException: next on empty iterator
	at scala.collection.Iterator$$anon$2.next(Iterator.scala:39)
	at scala.collection.Iterator$$anon$2.next(Iterator.scala:37)
	at scala.collection.IndexedSeqLike$Elements.next(IndexedSeqLike.scala:63)
	at scala.collection.IterableLike$class.head(IterableLike.scala:107)
	at scala.collection.mutable.ArrayOps$ofRef.scala$collection$IndexedSeqOptimized$$super$head(ArrayOps.scala:186)
	at scala.collection.IndexedSeqOptimized$class.head(IndexedSeqOptimized.scala:126)
	at scala.collection.mutable.ArrayOps$ofRef.head(ArrayOps.scala:186)
	at scala.collection.TraversableLike$class.last(TraversableLike.scala:459)
	at scala.collection.mutable.ArrayOps$ofRef.scala$collection$IndexedSeqOptimized$$super$last(ArrayOps.scala:186)
	at scala.collection.IndexedSeqOptimized$class.last(IndexedSeqOptimized.scala:132)
	at scala.collection.mutable.ArrayOps$ofRef.last(ArrayOps.scala:186)
	at org.apache.spark.sql.catalyst.util.QuantileSummaries.query(QuantileSummaries.scala:207)
	at org.apache.spark.sql.SparkPercentileCalculator$$anonfun$multipleApproxQuantiles$1$$anonfun$apply$1.apply$mcDD$sp(SparkPercentileCalculator.scala:91)
	at org.apache.spark.sql.SparkPercentileCalculator$$anonfun$multipleApproxQuantiles$1$$anonfun$apply$1.apply(SparkPercentileCalculator.scala:91)
	at org.apache.spark.sql.SparkPercentileCalculator$$anonfun$multipleApproxQuantiles$1$$anonfun$apply$1.apply(SparkPercentileCalculator.scala:91)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:245)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:245)
	at scala.collection.immutable.List.foreach(List.scala:381)
	at scala.collection.TraversableLike$class.map(TraversableLike.scala:245)
	at scala.collection.immutable.List.map(List.scala:285)
	at org.apache.spark.sql.SparkPercentileCalculator$$anonfun$multipleApproxQuantiles$1.apply(SparkPercentileCalculator.scala:91)
	at org.apache.spark.sql.SparkPercentileCalculator$$anonfun$multipleApproxQuantiles$1.apply(SparkPercentileCalculator.scala:91)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:245)
	at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:245)
	at scala.collection.IndexedSeqOptimized$class.foreach(IndexedSeqOptimized.scala:33)
	at scala.collection.mutable.ArrayOps$ofRef.foreach(ArrayOps.scala:186)
	at scala.collection.TraversableLike$class.map(TraversableLike.scala:245)
	at scala.collection.mutable.ArrayOps$ofRef.map(ArrayOps.scala:186)
	at org.apache.spark.sql.SparkPercentileCalculator.multipleApproxQuantiles(SparkPercentileCalculator.scala:91)
	at com.mineset.spark.statistics.model.ContinuousMinesetStats.quartiles$lzycompute(ContinuousMinesetStats.scala:274)
	at com.mineset.spark.statistics.model.ContinuousMinesetStats.quartiles(ContinuousMinesetStats.scala:272)
	at com.mineset.spark.statistics.model.MinesetStats.com$mineset$spark$statistics$model$MinesetStats$$serializeContinuousFeature$1(MinesetStats.scala:66)
	at com.mineset.spark.statistics.model.MinesetStats$$anonfun$calculateWithColumns$1.apply(MinesetStats.scala:118)
	at com.mineset.spark.statistics.model.MinesetStats$$anonfun$calculateWithColumns$1.apply(MinesetStats.scala:114)
	at scala.collection.immutable.List.foreach(List.scala:381)
	at com.mineset.spark.statistics.model.MinesetStats.calculateWithColumns(MinesetStats.scala:114)
	at com.mineset.spark.statistics.model.MinesetStats.toJson(MinesetStats.scala:46)
	at com.mineset.spark.statistics.model.MinesetStatsSuite$$anonfun$8.apply$mcV$sp(MinesetStatsSuite.scala:93)
	at com.mineset.spark.statistics.model.MinesetStatsSuite$$anonfun$8.apply(MinesetStatsSuite.scala:90)
	at com.mineset.spark.statistics.model.MinesetStatsSuite$$anonfun$8.apply(MinesetStatsSuite.scala:90)
	at org.scalatest.Transformer$$anonfun$apply$1.apply$mcV$sp(Transformer.scala:22)
	at org.scalatest.OutcomeOf$class.outcomeOf(OutcomeOf.scala:85)
	at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
	at org.scalatest.Transformer.apply(Transformer.scala:22)
	at org.scalatest.Transformer.apply(Transformer.scala:20)
	at org.scalatest.FunSuiteLike$$anon$1.apply(FunSuiteLike.scala:166)
	at org.scalatest.Suite$class.withFixture(Suite.scala:1122)
	at org.scalatest.FunSuite.withFixture(FunSuite.scala:1555)
	at org.scalatest.FunSuiteLike$class.invokeWithFixture$1(FunSuiteLike.scala:163)
	at org.scalatest.FunSuiteLike$$anonfun$runTest$1.apply(FunSuiteLike.scala:175)
	at org.scalatest.FunSuiteLike$$anonfun$runTest$1.apply(FunSuiteLike.scala:175)
	at org.scalatest.SuperEngine.runTestImpl(Engine.scala:306)
	at org.scalatest.FunSuiteLike$class.runTest(FunSuiteLike.scala:175)
	at org.scalatest.FunSuite.runTest(FunSuite.scala:1555)
	at org.scalatest.FunSuiteLike$$anonfun$runTests$1.apply(FunSuiteLike.scala:208)
	at org.scalatest.FunSuiteLike$$anonfun$runTests$1.apply(FunSuiteLike.scala:208)
	at org.scalatest.SuperEngine$$anonfun$traverseSubNodes$1$1.apply(Engine.scala:413)
	at org.scalatest.SuperEngine$$anonfun$traverseSubNodes$1$1.apply(Engine.scala:401)
	at scala.collection.immutable.List.foreach(List.scala:381)
	at org.scalatest.SuperEngine.traverseSubNodes$1(Engine.scala:401)
	at org.scalatest.SuperEngine.org$scalatest$SuperEngine$$runTestsInBranch(Engine.scala:396)
	at org.scalatest.SuperEngine.runTestsImpl(Engine.scala:483)
	at org.scalatest.FunSuiteLike$class.runTests(FunSuiteLike.scala:208)
	at org.scalatest.FunSuite.runTests(FunSuite.scala:1555)
	at org.scalatest.Suite$class.run(Suite.scala:1424)
	at org.scalatest.FunSuite.org$scalatest$FunSuiteLike$$super$run(FunSuite.scala:1555)
	at org.scalatest.FunSuiteLike$$anonfun$run$1.apply(FunSuiteLike.scala:212)
	at org.scalatest.FunSuiteLike$$anonfun$run$1.apply(FunSuiteLike.scala:212)
	at org.scalatest.SuperEngine.runImpl(Engine.scala:545)
	at org.scalatest.FunSuiteLike$class.run(FunSuiteLike.scala:212)
	at com.mineset.spark.statistics.model.MinesetStatsSuite.org$scalatest$BeforeAndAfterAll$$super$run(MinesetStatsSuite.scala:30)
	at org.scalatest.BeforeAndAfterAll$class.liftedTree1$1(BeforeAndAfterAll.scala:257)
	at org.scalatest.BeforeAndAfterAll$class.run(BeforeAndAfterAll.scala:256)
	at com.mineset.spark.statistics.model.MinesetStatsSuite.run(MinesetStatsSuite.scala:30)
	at org.scalatest.tools.SuiteRunner.run(SuiteRunner.scala:55)
	at org.scalatest.tools.Runner$$anonfun$doRunRunRunDaDoRunRun$3.apply(Runner.scala:2563)
	at org.scalatest.tools.Runner$$anonfun$doRunRunRunDaDoRunRun$3.apply(Runner.scala:2557)
	at scala.collection.immutable.List.foreach(List.scala:381)
	at org.scalatest.tools.Runner$.doRunRunRunDaDoRunRun(Runner.scala:2557)
	at org.scalatest.tools.Runner$$anonfun$runOptionallyWithPassFailReporter$2.apply(Runner.scala:1044)
	at org.scalatest.tools.Runner$$anonfun$runOptionallyWithPassFailReporter$2.apply(Runner.scala:1043)
	at org.scalatest.tools.Runner$.withClassLoaderAndDispatchReporter(Runner.scala:2722)
	at org.scalatest.tools.Runner$.runOptionallyWithPassFailReporter(Runner.scala:1043)
	at org.scalatest.tools.Runner$.run(Runner.scala:883)
	at org.scalatest.tools.Runner.run(Runner.scala)
	at org.jetbrains.plugins.scala.testingSupport.scalaTest.ScalaTestRunner.runScalaTest2(ScalaTestRunner.java:138)
	at org.jetbrains.plugins.scala.testingSupport.scalaTest.ScalaTestRunner.main(ScalaTestRunner.java:28)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)

Issue Links

• duplicates: SPARK-19573 Make NaN/null handling consistent in approxQuantile
• requires: SPARK-19573 Make NaN/null handling consistent in approxQuantile