Perform groupBy with array of strings

I have an array of strings defined in a variable which contains name of the column. I would like to perform group by and get count.

I am trying below code but throws error.

val keys = Array("Col1", "Col2")
val grouppedByDf = myDf.groupBy(keys.mkString(",").count

Can you please guide me what I am doing wrong here ?

CodePudding user response：

import spark.implicits._

val df = Seq(("βήτα", "άλφα", 20), ("άλφα", "βήτα", 10), ("άλφα", "βήτα", 20), ("βήτα", "άλφα", 10)).toDF("α", "β", "ω")
val keys = Array("α", "β")
df
  .groupBy(keys.map(col(_)): _*)
  .count()
  .show()

 ---- ---- ----- 
|   α|   β|count|
 ---- ---- ----- 
|βήτα|άλφα|    2|
|άλφα|βήτα|    2|
 ---- ---- -----