[ 
https://issues.apache.org/jira/browse/SPARK-20174?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15972211#comment-15972211
 ] 

Takeshi Yamamuro edited comment on SPARK-20174 at 4/18/17 6:54 AM:
-------------------------------------------------------------------

To fix this, IMHO it's okay to accept Seq[String] in the first argument of 
withColumn for multi aliases;

{code}
scala> val df = Seq((Seq(1, 2, 3))).toDF("a")
scala> df.select(posexplode($"a").as("p" :: "c" :: Nil)).show
+---+---+
|  p|  c|
+---+---+
|  0|  1|
|  1|  2|
|  2|  3|
+---+---+

scala> df.withColumn("p" :: "c" :: Nil, posexplode($"a")).show
<console>:26: error: type mismatch;
 found   : List[String]
 required: String
       df.withColumn("p" :: "c" :: Nil, posexplode($"a")).show
{code}


was (Author: maropu):
To fix this, it seems to be okay to accept Seq[String] in the first argument of 
withColumn for multi aliases;

{code}
scala> val df = Seq((Seq(1, 2, 3))).toDF("a")
scala> df.select(posexplode($"a").as("p" :: "c" :: Nil)).show
+---+---+
|  p|  c|
+---+---+
|  0|  1|
|  1|  2|
|  2|  3|
+---+---+

scala> df.withColumn("p" :: "c" :: Nil, posexplode($"a")).show
<console>:26: error: type mismatch;
 found   : List[String]
 required: String
       df.withColumn("p" :: "c" :: Nil, posexplode($"a")).show
{code}

> Analyzer gives mysterious AnalysisException when posexplode used in withColumn
> ------------------------------------------------------------------------------
>
>                 Key: SPARK-20174
>                 URL: https://issues.apache.org/jira/browse/SPARK-20174
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 2.2.0
>            Reporter: Jacek Laskowski
>            Priority: Minor
>
> Wish I knew how to even describe the issue. It appears that {{posexplode}} 
> cannot be used in {{withColumn}}, but the error message does not seem to say 
> it.
> [The scaladoc of 
> posexplode|http://spark.apache.org/docs/latest/api/scala/index.html#org.apache.spark.sql.functions$@posexplode(e:org.apache.spark.sql.Column):org.apache.spark.sql.Column]
>  is silent about this "limitation", too.
> {code}
> scala> codes.printSchema
> root
>  |-- id: integer (nullable = false)
>  |-- rate_plan_code: array (nullable = true)
>  |    |-- element: string (containsNull = true)
> scala> codes.withColumn("code", posexplode($"rate_plan_code")).show
> org.apache.spark.sql.AnalysisException: The number of aliases supplied in the 
> AS clause does not match the number of columns output by the UDTF expected 2 
> aliases but got code ;
>   at 
> org.apache.spark.sql.catalyst.analysis.CheckAnalysis$class.failAnalysis(CheckAnalysis.scala:40)
>   at 
> org.apache.spark.sql.catalyst.analysis.Analyzer.failAnalysis(Analyzer.scala:90)
>   at 
> org.apache.spark.sql.catalyst.analysis.Analyzer$ResolveGenerate$.makeGeneratorOutput(Analyzer.scala:1744)
>   at 
> org.apache.spark.sql.catalyst.analysis.Analyzer$ExtractGenerator$$anonfun$apply$20$$anonfun$56.apply(Analyzer.scala:1691)
>   at 
> org.apache.spark.sql.catalyst.analysis.Analyzer$ExtractGenerator$$anonfun$apply$20$$anonfun$56.apply(Analyzer.scala:1679)
>   at 
> scala.collection.TraversableLike$$anonfun$flatMap$1.apply(TraversableLike.scala:241)
>   at 
> scala.collection.TraversableLike$$anonfun$flatMap$1.apply(TraversableLike.scala:241)
>   at 
> scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
>   at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:48)
>   at scala.collection.TraversableLike$class.flatMap(TraversableLike.scala:241)
>   at scala.collection.AbstractTraversable.flatMap(Traversable.scala:104)
>   at 
> org.apache.spark.sql.catalyst.analysis.Analyzer$ExtractGenerator$$anonfun$apply$20.applyOrElse(Analyzer.scala:1679)
>   at 
> org.apache.spark.sql.catalyst.analysis.Analyzer$ExtractGenerator$$anonfun$apply$20.applyOrElse(Analyzer.scala:1664)
>   at 
> org.apache.spark.sql.catalyst.plans.logical.LogicalPlan$$anonfun$resolveOperators$1.apply(LogicalPlan.scala:62)
>   at 
> org.apache.spark.sql.catalyst.plans.logical.LogicalPlan$$anonfun$resolveOperators$1.apply(LogicalPlan.scala:62)
>   at 
> org.apache.spark.sql.catalyst.trees.CurrentOrigin$.withOrigin(TreeNode.scala:70)
>   at 
> org.apache.spark.sql.catalyst.plans.logical.LogicalPlan.resolveOperators(LogicalPlan.scala:61)
>   at 
> org.apache.spark.sql.catalyst.analysis.Analyzer$ExtractGenerator$.apply(Analyzer.scala:1664)
>   at 
> org.apache.spark.sql.catalyst.analysis.Analyzer$ExtractGenerator$.apply(Analyzer.scala:1629)
>   at 
> org.apache.spark.sql.catalyst.rules.RuleExecutor$$anonfun$execute$1$$anonfun$apply$1.apply(RuleExecutor.scala:85)
>   at 
> org.apache.spark.sql.catalyst.rules.RuleExecutor$$anonfun$execute$1$$anonfun$apply$1.apply(RuleExecutor.scala:82)
>   at 
> scala.collection.LinearSeqOptimized$class.foldLeft(LinearSeqOptimized.scala:124)
>   at scala.collection.immutable.List.foldLeft(List.scala:84)
>   at 
> org.apache.spark.sql.catalyst.rules.RuleExecutor$$anonfun$execute$1.apply(RuleExecutor.scala:82)
>   at 
> org.apache.spark.sql.catalyst.rules.RuleExecutor$$anonfun$execute$1.apply(RuleExecutor.scala:74)
>   at scala.collection.immutable.List.foreach(List.scala:381)
>   at 
> org.apache.spark.sql.catalyst.rules.RuleExecutor.execute(RuleExecutor.scala:74)
>   at 
> org.apache.spark.sql.execution.QueryExecution.analyzed$lzycompute(QueryExecution.scala:70)
>   at 
> org.apache.spark.sql.execution.QueryExecution.analyzed(QueryExecution.scala:68)
>   at 
> org.apache.spark.sql.execution.QueryExecution.assertAnalyzed(QueryExecution.scala:51)
>   at org.apache.spark.sql.Dataset$.ofRows(Dataset.scala:67)
>   at 
> org.apache.spark.sql.Dataset.org$apache$spark$sql$Dataset$$withPlan(Dataset.scala:2832)
>   at org.apache.spark.sql.Dataset.select(Dataset.scala:1137)
>   at org.apache.spark.sql.Dataset.withColumn(Dataset.scala:1882)
>   ... 48 elided
> scala> codes.select(posexplode($"rate_plan_code")).show
> +---+------+
> |pos|   col|
> +---+------+
> |  0|   AAA|
> |  1|  RACK|
> |  2|SMOBIX|
> |  3|SMOBPX|
> +---+------+
> {code}



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