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I am trying to split Scala list like List(1,2,3,4) into pairs (1,2) (2,3) (3,4), what's a simple way to do this?
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A list is a combination of pairs that creates a linked list. More precisely, a list is either the empty list null, or it is a pair whose first element is a list element and whose second element is a list.
To append value inside the list object we have two approach shown below: val variable_name = List(value1, value2, value3 , soon..) 2. To assign value for ListBuffer we use += operator to assign its value anytime because ListBuffer is mutable in nature.
Scala Lists are quite similar to arrays which means, all the elements of a list have the same type but there are two important differences. First, lists are immutable, which means elements of a list cannot be changed by assignment. Second, lists represent a linked list whereas arrays are flat.
val xs = List(1,2,3,4)
xs zip xs.tail
// res1: List[(Int, Int)] = List((1,2), (2,3), (3,4))
As the docs say, zip
Returns a list formed from this list and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.
So List('a,'b,'c,'d) zipped with List('x,'y,'z) is List(('a,'x), ('b,'y), ('c,'z)) with the final 'd of the first one ignored.
From your example, the tail of List(1,2,3,4) is List(2,3,4) so you can see how these zip together in pairs.
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To produce a list of pairs (i.e. tuples) try this
List(1,2,3,4,5).sliding(2).collect{case List(a,b) => (a,b)}.toList
List(1,2,3,4).sliding(2).map(x => (x.head, x.tail.head)).toList
res0: List[(Int, Int)] = List((1,2), (2,3), (3,4))
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