How to use Column.isin with list?
ScalaApache SparkApache Spark-SqlScala Problem Overview
val items = List("a", "b", "c")
sqlContext.sql("select c1 from table")
.filter($"c1".isin(items))
.collect
.foreach(println)
The code above throws the following exception.
Exception in thread "main" java.lang.RuntimeException: Unsupported literal type class scala.collection.immutable.$colon$colon List(a, b, c)
at org.apache.spark.sql.catalyst.expressions.Literal$.apply(literals.scala:49)
at org.apache.spark.sql.functions$.lit(functions.scala:89)
at org.apache.spark.sql.Column$$anonfun$isin$1.apply(Column.scala:642)
at org.apache.spark.sql.Column$$anonfun$isin$1.apply(Column.scala:642)
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.WrappedArray.foreach(WrappedArray.scala:35)
at scala.collection.TraversableLike$class.map(TraversableLike.scala:245)
at scala.collection.AbstractTraversable.map(Traversable.scala:104)
at org.apache.spark.sql.Column.isin(Column.scala:642)
Below is my attempt to fix it. It compiles and runs but doesn't return any match. Not sure why.
val items = List("a", "b", "c").mkString("\"","\",\"","\"")
sqlContext.sql("select c1 from table")
.filter($"c1".isin(items))
.collect
.foreach(println)
Scala Solutions
Solution 1 - Scala
According to documentation, isin takes a vararg, not a list. List is actually a confusing name here. You can try converting your List to vararg like this:
val items = List("a", "b", "c")
sqlContext.sql("select c1 from table")
.filter($"c1".isin(items:_*))
.collect
.foreach(println)
Your variant with mkString compiles, because one single String is also a vararg (with number of arguments equal to 1), but it is proably not what you want to achieve.
Solution 2 - Scala
It worked like this in Java Api (Java 8)
.isin(sampleListName.stream().toArray(String[]::new))));
sampleListName is a List
Solution 3 - Scala
Spark has now (since 2.4.0) a method called isInCollection, which is just what you are looking for, instead of isIn.
(shouldn't they unify the methods?)
Solution 4 - Scala
As Tomalak has mentioned it :
isin(java.lang.Object... list)
A boolean expression that is evaluated to true if the value
of this expression is contained by the evaluated values of the arguments.
Therefore, you just could fix this making the following change :
val items = List("a", "b", "c").map(c => s""""$c"""")
Solution 5 - Scala
Even easier:
sqlContext.sql("select c1 from table")
.filter($"c1".isin("a", "b", "c"))
.collect
.foreach(println)
Unless you have a lot of list values, which isn't the case usually.