Spark dataframe drop duplicates

Question

Is it possible possible to tell spark drop duplicates to drop the second occurrence instead of first one?

scala> df.show()
+-----------+
|         _1|
+-----------+
|1 2 3 4 5 6|
|9 4 5 8 7 7|
|1 2 3 4 5 6|
+-----------+


scala> val newDf = df.dropDuplicates()
newDf: org.apache.spark.sql.DataFrame = [_1: string]

scala> newDf.show()
+-----------+                                                                   
|         _1|
+-----------+
|9 4 5 8 7 7|
|1 2 3 4 5 6|
+-----------+

Answer 1

对行进行排名/索引，具有相同的值，然后删除索引/排名 > 1 的所有记录的条目。