Github user ueshin commented on a diff in the pull request: https://github.com/apache/spark/pull/21045#discussion_r190181477 --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/collectionOperations.scala --- @@ -127,6 +127,176 @@ case class MapKeys(child: Expression) override def prettyName: String = "map_keys" } +@ExpressionDescription( + usage = """_FUNC_(a1, a2, ...) - Returns a merged array containing in the N-th position the + N-th value of each array given.""", + examples = """ + Examples: + > SELECT _FUNC_(array(1, 2, 3), array(2, 3, 4)); + [[1, 2], [2, 3], [3, 4]] + > SELECT _FUNC_(array(1, 2), array(2, 3), array(3, 4)); + [[1, 2, 3], [2, 3, 4]] + """, + since = "2.4.0") +case class Zip(children: Seq[Expression]) extends Expression with ExpectsInputTypes { + + override def inputTypes: Seq[AbstractDataType] = Seq.fill(children.length)(ArrayType) + + override def dataType: DataType = ArrayType(mountSchema) + + override def nullable: Boolean = children.forall(_.nullable) + + private lazy val arrayTypes = children.map(_.dataType.asInstanceOf[ArrayType]) + + private lazy val arrayElementTypes = arrayTypes.map(_.elementType) + + + def mountSchema: StructType = { + val fields = arrayTypes.zipWithIndex.map { case (arr, idx) => + val fieldName = if (children(idx).isInstanceOf[NamedExpression]) { + children(idx).asInstanceOf[NamedExpression].name + } else { + s"$idx" + } + StructField(fieldName, arr.elementType, children(idx).nullable || arr.containsNull) + } --- End diff -- How about: ```scala val fields = children.zip(arrayElementTypes).zipWithIndex.map { case ((expr: NamedExpression, elementType), _) => StructField(expr.name, elementType, nullable = true) case ((_, elementType), idx) => StructField(s"$idx", elementType, nullable = true) } ``` ?
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