CODEWITHSUNDEEP
scalascala-collections
Explorer
Explorer

Reputation: 1647

comparing the index of element in scala list

I have 2 list 

val listA = List("Mary", "Harry", "Marry", "Harry", "Marry")
val listB = List("Mary", "Harry", "Marry", "Harry", "Marry")

Now I want to know whether the index of all occurrences of Harry in both the list are same or not. What is the best way to do it in scala?

Upvotes: 0

Views: 506

Answers (2)

megri
megri

Reputation: 1019

I'd use iterators to compare only as much as needed, like so:

def indexesOf(ls: List[String], word: String) =
  ls.iterator.zipWithIndex.collect { case (`word`, i) => i }

indexesOf(listA, "Harry") sameElements indexesOf(listB, "Harry")

Upvotes: 4

Marth
Marth

Reputation: 24802

You could .zip the lists together and then use .exists to check whether there is a tuple where one equals "Harry" and the other does not:

scala> val listA = List("Mary", "Harry", "Marry", "Harry", "Marry")
listA: List[String] = List(Mary, Harry, Marry, Harry, Marry)

scala> val listB = List("Mary", "Harry", "Marry", "Harry", "Marry")
listB: List[String] = List(Mary, Harry, Marry, Harry, Marry)

scala> (listA zip listB).exists { case (a, b) => (a == "Harry" ^ b == "Harry") }
res5: Boolean = false

scala> val listA = List("Mary", "Harry", "Marry", "Harry", "Marry")
listA: List[String] = List(Mary, Harry, Marry, Harry, Marry)

scala> val listB = List("Mary", "Harry", "Marry", "Harry", "Harry") // changed the last one
listB: List[String] = List(Mary, Harry, Marry, Harry, Harry)

scala> (listA zip listB).exists { case (a, b) => (a == "Harry" ^ b == "Harry") }
res6: Boolean = true

Upvotes: 2

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