Iterators
slidingO
The circular equivalent of sliding.
Example
Seq(0, 1, 2).slidingO(2) // Iterator(Seq(0, 1), Seq(1, 2), Seq(2, 0))```
Compared to standard
In the same example the standard version behaves differently, does not pass the “sliding window” on the last and first elements.
Seq(0, 1, 2).sliding(2) // Iterator(Seq(0, 1), Seq(1, 2))```
rotations
All possible rotations.
Starting from itself and moving one rotation step to the left.
Example
Seq(0, 1, 2).rotations // Iterator(Seq(0, 1, 2), Seq(1, 2, 0), Seq(2, 0, 1))
On empty seq
Just itself on empty Seq.
Seq.empty.rotations // Iterator(Seq())
reversions
2 sequences, the sequence itself and reversed.
Example
Seq(0, 1, 2).reversions // Iterator(Seq(0, 1, 2), Seq(2, 1, 0))
On empty seq
Just itself on empty Seq.
Seq.empty.reversions // Iterator(Seq())
reflections
2 sequences, the sequence itself and reflected at the start.
Example
Seq(0, 1, 2).reflections // Iterator(Seq(0, 1, 2), Seq(0, 2, 1))
On empty seq
Just itself on empty Seq.
Seq.empty.reflections // Iterator(Seq())
rotationsAndReflections
All possible rotations and reflections.
Starting from itself and moving one rotation step to the right, then reversing and doing the same.
Example
Seq(0, 1, 2).rotationsAndReflections // Iterator(Seq(0, 1, 2), Seq(1, 2, 0), Seq(2, 0, 1), Seq(0, 2, 1), Seq(2, 1, 0), Seq(1, 0, 2))
On empty seq
Just itself on empty Seq.
Seq.empty.rotationsAndReflections // Iterator(Seq())
groupedO
The circular equivalent of grouped — partitions the ring into ceil(n / size) non-overlapping fixed-size blocks.
Unlike standard grouped, the final block wraps across the seam between the last and first elements, so every block has exactly size elements.
Example
"ABCDE".groupedO(2).toList.map(_.mkString) // List("AB", "CD", "EA")
Without wrap
When size divides the ring length, no wrap is needed.
"ABCDEF".groupedO(2).toList.map(_.mkString) // List("AB", "CD", "EF")
Block larger than the ring
When size > n, a single block wraps around multiple times.
"AB".groupedO(5).toList.map(_.mkString) // List("ABABA")
On empty seq
Seq.empty.groupedO(2).toList // Nil
zipWithIndexO
The circular equivalent of zipWithIndex, pairing each element with its original (circular) index rather than its position in the iterator. Accepts an optional starting circular index.
Example
Seq('a', 'b', 'c').zipWithIndexO(1).toList // List(('b', 1), ('c', 2), ('a', 0))
Default
Starting at index 0 produces the same output as zipWithIndex.
Seq('a', 'b', 'c').zipWithIndexO().toList // List(('a', 0), ('b', 1), ('c', 2))