How to use aioitertools - 10 common examples

Yield the running accumulation of an iterable and operator.

    Accepts both a standard function or a coroutine for accumulation.

    Example:

        data = [1, 2, 3, 4]

        async def mul(a, b):
            return a * b

        async for total in accumulate(data, func=mul):
            ...  # 1, 2, 6, 24

    """
    itr = iter(itr)
    try:
        total: T = await next(itr)
    except AnyStop:
        return

    yield total
    async for item in itr:
        total = await maybe_await(func(total, item))
        yield total

Example:

        data = ["A", "a", "b", "c", "C", "c"]

        async for key, group in groupby(data, key=str.lower):
            key  # "a", "b", "c"
            group  # ["A", "a"], ["b"], ["c", "C", "c"]

    """
    if key is None:
        key = lambda x: x

    grouping: List[T] = []

    it = iter(itr)
    item = await next(it)
    grouping = [item]

    j = await maybe_await(key(item))
    async for item in it:
        k = await maybe_await(key(item))
        if k != j:
            yield j, grouping
            grouping = [item]
        else:
            grouping.append(item)
        j = k

    yield j, grouping

) -> AsyncIterator[T]:
    """
    Yield items from the iterable only when the predicate evaluates to False.

    Accepts both standard functions and coroutines for the predicate.

    Example:

        def pred(x):
            return x < 4

        async for item in filterfalse(pred, range(6)):
            ...  # 4, 5

    """
    async for item in iter(iterable):
        if not await maybe_await(predicate(item)):
            yield item

) -> AsyncIterator[T]:
    """
    Drops all items until the predicate evaluates False; yields all items afterwards.

    Accepts both standard functions and coroutines for the predicate.

    Example:

        def pred(x):
            return x < 4

        async for item in dropwhile(pred, range(6)):
            ...  # 4, 5, 6

    """
    itr = iter(iterable)
    async for item in itr:
        if not await maybe_await(predicate(item)):
            yield item
            break
    async for item in itr:
        yield item

async def map(fn: Callable[[T], R], itr: AnyIterable[T]) -> AsyncIterator[R]:
    """
    Modify item of a mixed iterable using the given function or coroutine.

    Example:

        async for response in map(func, data):
            ...

    """
    # todo: queue items eagerly
    async for item in iter(itr):
        yield await maybe_await(fn(item))

async for key, group in groupby(data, key=str.lower):
            key  # "a", "b", "c"
            group  # ["A", "a"], ["b"], ["c", "C", "c"]

    """
    if key is None:
        key = lambda x: x

    grouping: List[T] = []

    it = iter(itr)
    item = await next(it)
    grouping = [item]

    j = await maybe_await(key(item))
    async for item in it:
        k = await maybe_await(key(item))
        if k != j:
            yield j, grouping
            grouping = [item]
        else:
            grouping.append(item)
        j = k

    yield j, grouping

Yield values from a function using an iterable of iterables for arguments.

    Each iterable contained within will be unpacked and consumed before
    executing the function or coroutine.

    Example:

        data = [(1, 1), (1, 1, 1), (2, 2)]

        async for value in starmap(operator.add, data):
            ...  # 2, 3, 4

    """
    async for itr in iter(iterable):
        args = await list(itr)
        yield await maybe_await(fn(*args))

async def mul(a, b):
            return a * b

        async for total in accumulate(data, func=mul):
            ...  # 1, 2, 6, 24

    """
    itr = iter(itr)
    try:
        total: T = await next(itr)
    except AnyStop:
        return

    yield total
    async for item in itr:
        total = await maybe_await(func(total, item))
        yield total

"""
    Yield values from the iterable until the predicate evaluates False.

    Accepts both standard functions and coroutines for the predicate.

    Example:

        def pred(x):
            return x < 4

        async for value in takewhile(pred, range(8)):
            ...  # 0, 1, 2, 3

    """
    async for item in iter(iterable):
        if await maybe_await(predicate(item)):
            yield item
        else:
            break

Example:

        data = ["A", "a", "b", "c", "C", "c"]

        async for key, group in groupby(data, key=str.lower):
            key  # "a", "b", "c"
            group  # ["A", "a"], ["b"], ["c", "C", "c"]

    """
    if key is None:
        key = lambda x: x

    grouping: List[T] = []

    it = iter(itr)
    item = await next(it)
    grouping = [item]

    j = await maybe_await(key(item))
    async for item in it:
        k = await maybe_await(key(item))
        if k != j:
            yield j, grouping
            grouping = [item]
        else:
            grouping.append(item)
        j = k

    yield j, grouping