CODEWITHSUNDEEP
scalafunctional-programmingstream
N M
N M

Reputation: 9

Split stream into two streams

Define the "split" function that divides a stream into two streams. The first list should contain elements with odd indexes and the second with even indexes. Example: split(Stream(5, 6, 3, 2, 1)) -> Stream(5, 3, 1) and Stream(6, 2)

My attempt:

 def split(originalElements: Stream[Any]): (Stream[Any], Stream[Any]) = {
  var oddList: Stream[Any] = Stream();
  var evenList: Stream[Any] = Stream();

  for (i <- 0 until originalElements.length) {
    if (i % 2 == 0) {
      oddList = oddList :+ originalElements(i)
    } else {
      evenList = evenList :+ originalElements(i)
    }
  }

  (oddList, evenList)
}

  println(split(Stream(5, 6, 3, 2, 1)))

I get this output -> (Stream(5, <not computed>),Stream(6, <not computed>))

I'm somehow confused in stream functions, could someone help me to understand what is wrong in this code and why I don't get the right output? Thank you in advance!

Upvotes: 0

Views: 146

Answers (1)

Stanislav Kovalenko
Stanislav Kovalenko

Reputation: 763

You can try to use partitioning function or reimplement it with filter and filterNot functions by yourself. Stream isn't a list, you shouldn't use length. Stream might be infinite.

  val s = Stream(5, 6, 3, 2, 1)

  val (oddStream, evenStream) = {
    val (odd, even) = s.zipWithIndex.partition {
      case (_, i) => i % 2 == 0
    }
    (odd.map(_._1), even.map(_._1))
  }

Upvotes: 2

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