CODEWITHSUNDEEP
stringscalalist
sonal pingle
sonal pingle

Reputation: 57

Convert List[List[Any]] into List[List[String]] in Scala

I have the following List[List[Any]] which I want to convert to List[List[String]].

val input:List[List[Any]] = List(List(1234), List(234, 678), List(8765, 90876, 1))

I am looking for the following output:

val output:List[List[String]] = List(List(1234), List(234, 678), List(8765, 90876, 1))

I have tried doing the following:

val output:List[List[String]] = input.map(_.toString).toList
// or 
val output:List[List[String]] = input.map(_.toString)

None of the above give me the desired output.

Upvotes: 1

Views: 786

Answers (1)

Ra Ka
Ra Ka

Reputation: 3055

Because, your list is nested, you need to map it twice.

Why below is not working?

val output:List[List[String]] = input.map(_.toString)

Because, _ placeholder holds value of type List[String] and applying toString method convert the List to String and hence result will be of type List[String] instead of List[List[String]].

scala> input.map(_.toString)
res2: List[String] = List(List(1234), List(234, 678), List(8765, 90876, 1))

Therefore, you need to map input twice. 

scala> input.map(_.map(_.toString))
res0: List[List[String]] = List(List(1234), List(234, 678), List(8765, 90876, 1))

Upvotes: 3

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