Question

Having an IndexedSeq, how to iterate it from the end to the beginning?

Answer 1

You can call reverseIterator if you just want to iterate it from end to beginning. If you want to apply a map, reverseMap. foldLeft and foldRight traverse in opposite directions, so each can be thought of as the other on the reversed list; likewise with reduceRight and scanRight. There are a bunch of last methods to find things near the end instead of the beginning. Anything else, and reverse (to recreate the whole collection) or .view.reverse.whatever if you don’t want to duplicate the collection in memory. For a simple foreach, reverseIterator will generally do the trick.