itertools_window.py

from collections import deque
from typing import TypeVar, Iterable, Iterator


T = TypeVar("T")


def window(i: Iterable[T], size: int = 2) -> Iterator[tuple[T, ...]]:
    """Yield a sliding window of items from an iterator."""
    i: Iterable[T] = iter(i)
    w: deque[T] = deque()

    qsize = max(1, size)

    for _ in range(qsize):
        try:
            w.append(next(i))
        except StopIteration:
            yield tuple(w)
            return

    yield tuple(w)

    for e in i:
        w.append(e)
        w.popleft()
        yield tuple(w)