Scala list of list count different elements per sublist index

Question

I have a list of lists with the following data

val list = List(List("a","b","c"),List("d","e","f"),List("a","a","a"))

I want to disicover how many different data do I have in each position of the sublists

1 -> List("a","d","a")

2 -> List("b","e","a")

3 -> List("c","f","a")

Is there a way to do that? It doesn't need to be indexed, but I need the amount of different values per sublist index, the result could also be

2 // different values a and d

3 // different values b, e and a

3 // different values c, f and a

Answer 1

As I noted in a comment on Jhonny Everson's (almost right but now deleted) answer, you can use transpose to get a list of the columns, and then distinct to remove duplicates:

scala> list.transpose.map(_.distinct.size)
res0: List[Int] = List(2, 3, 3)

This will throw an exception if all the lists don't have the same size, but that's probably what you want.