CODEWITHSUNDEEP
scalamatrixcasting
MeditationOrBust
MeditationOrBust

Reputation: 21

How to convert a 2-d array to 2-d list scala

In the middle of learning Scala.

Having a hard time understanding creating an 2-d array then converting it to a 2-d list.

I would think creating an empty List[List]] then iterating through the array while converting each array to a list and appending it to a the list.

This throws an error

var arr = Array(Array(0, 1), Array(2, 3))
var ans = List[List[Int]]()
    
for (e <- arr) {
  ans += e.toList
}

Then I am given a type mismatch error:

found: List[Int]

required: Int

This error doesn't make sense to me.

Upvotes: 0

Views: 100

Answers (1)

Andrey Tyukin
Andrey Tyukin

Reputation: 44928

Just

val ans = arr.map(_.toList).toList

If (for whatever reason) you wanted to make your loop run, you'd have to use :+=, which would be desugared into ans = ans :+ e.toList:

for (e <- arr) {
  ans :+= e.toList
}

Note, however, that it would be way slower than the map (like, wrong asymptotic behavior kind of slower, i.e. really bad), because appending to a list with :+ requires rebuilding the entire list in every iteration.

Upvotes: 2

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