islice(iterable, stop)

islice(iterable, start, stop, [step])

• Returns an iterator that produces the selected elements from the iterable. It skips start elements from the iterable, and then produces values until stop is reached, or until the iterator is exhausted. This affects execution speed when it needs to skip lots of elements.
• It's memory efficient because it doesn't allocate extra memory for the iterated elements, and it can be used to slice both iterables and iterators. Standard indexing (a[start:stop]) doesn't work on iterators because they don't implement __getitem__().

slice(stop)

slice(start, stop, [step])

• Standard indexing relies on slice(): a[start:stop:step] calls a.__getitem__(slice(start, stop, step)).
• slice() creates a shallow copy of the selected elements fro...