将dataframe列转换为元组列表

我有:

val DF1 = sparkSession.sql("select col1,col2,col3 from table");
val tupleList = DF1.select("col1","col2").rdd.map(r => (r(0),r(1))).collect()

tupleList.foreach(x=> x.productIterator.foreach(println))

但是我没有得到输出中的所有元组.问题在哪里？

col1 col2
AA  CCC
AA  BBB 
DD  CCC 
AB  BBB 
Others  BBB 
GG  ALL 
EE  ALL 
Others  ALL 
ALL BBB 
NU FFF 
NU  Others 
Others  Others 
C   FFF 

我得到的输出是: CCC AA BBB AA Others AA Others DD ALL Others ALL GG ALL ALL

scala> val hiveContext = new org.apache.spark.sql.hive.HiveContext(sc)
scala> val df1 = hiveContext.sql("select id, name from class_db.students")
scala> df1.show()
+----+-------+
|  id|   name|
+----+-------+
|1001|   John|
|1002|Michael|
+----+-------+

scala> df1.select("id", "name").rdd.map(x => (x.get(0), x.get(1))).collect()
res3: Array[(Any, Any)] = Array((1001,John), (1002,Michael))