scala_sliding.scala

// sliding[B >: A](size: Int, step: Int = 1): GroupedIterator[B]
// Returns an iterator which presents a "sliding window" view of another iterator. 
// The first argument is the window size, and the second is how far to advance the window on each iteration; defaults to 1. 
// Example usages:

// Returns List(List(1, 2, 3), List(2, 3, 4), List(3, 4, 5))
(1 to 5).iterator.sliding(3).toList
// Returns List(List(1, 2, 3, 4), List(4, 5))
(1 to 5).iterator.sliding(4, 3).toList
// Returns List(List(1, 2, 3, 4))
(1 to 5).iterator.sliding(4, 3).withPartial(false).toList
// Returns List(List(1, 2, 3, 4), List(4, 5, 20, 25))
// Illustrating that withPadding's argument is by-name.
val it2 = Iterator.iterate(20)(_ + 5)
(1 to 5).iterator.sliding(4, 3).withPadding(it2.next).toList

// Note: 
// Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. 
// Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.