How to extract elements from 4 lists in scala?

Question

case class TargetClass(key: Any, value: Number, lowerBound: Double, upperBound: Double)

val keys: List[Any] = List("key1", "key2", "key3")
val values: List[Number] = List(1,2,3);
val lowerBounds: List[Double] = List(0.1, 0.2, 0.3)
val upperBounds: List[Double] = List(0.5, 0.6, 0.7)

Now I want to construct a List[TargetClass] to hold the 4 lists. Does anyone know how to do it efficiently? Is using for-loop to add elements one by one very inefficient?

I tried to use zipped, but it seems that this only applies for combining up to 3 lists.

Thank you very much!

Answer 1

One approach:

keys.zipWithIndex.map {
  case (item,i)=> TargetClass(item,values(i),lowerBounds(i),upperBounds(i))
}

You may want to consider using the lift method to deal with case of lists being of unequal lengths (and thereby provide a default if keys is longer than any of the lists?)

I realise this doesn't address your question of efficiency. You could fairly easily run some tests on different approaches.