def findMultipleDF(df: DataFrame, NHighest:Int): Map[String, DataFrame] = {
  val map = Map[String, DataFrame]()
  val rankedDF = df.withColumn("Rank", rank().over(Window.partitionBy("team").orderBy($"hits".desc)))
  val count = df.groupBy("team").count().collect()
  count.map(x => {
    val tempDF = rankedDF.filter($"team" === x.get(0) && col("Rank").leq(NHighest)).toDF()
    map.+=((x.get(0).toString(), tempDF))
  })
  map
}

val output = findMultipleDF(team_df, 2)
output.map(x=>{
  x._2.show()
})
+-------+--------------+----+----+
|   team|        player|hits|Rank|
+-------+--------------+----+----+
|dodgers|cody bellinger|  20|   1|
|dodgers| justin turner|  15|   2|
+-------+--------------+----+----+
+-------+-----------------+----+----+
|   team|           player|hits|Rank|
+-------+-----------------+----+----+
|yankees|      aaron judge|  24|   1|
|yankees|giancarlo stanton|  20|   2|
+-------+-----------------+----+----+

您可以像上面那样尝试，但不确定为什么要在不同的Dataframe中输出。