Skip to main content
Donate to the Python Software Foundation or Purchase a PyCharm License to Benefit the PSF! Donate Now

Generator-based operators for asynchronous iteration

Project description

Generator-based operators for asynchronous iteration

Synopsis

aiostream provides a collection of stream operators that can be combined to create asynchronous pipelines of operations.

It can be seen as an asynchronous version of itertools, although some aspects are slightly different. Essentially, all the provided operators return a unified interface called a stream. A stream is an enhanced asynchronous iterable providing the following features:

  • Operator pipe-lining - using pipe symbol |
  • Repeatability - every iteration creates a different iterator
  • Safe iteration context - using async with and the stream method
  • Simplified execution - get the last element from a stream using await
  • Slicing and indexing - using square brackets []
  • Concatenation - using addition symbol +

Requirements

The stream operators rely heavily on asynchronous generators (PEP 525):

  • python >= 3.6

Stream operators

The stream operators are separated in 7 categories:

creation iterate, preserve, just, empty, throw, never, repeat, count, range
transformation map, enumerate, starmap, cycle, chunks
selection take, takelast, skip, skiplast, getitem, filter, takewhile, dropwhile
combination map, zip, merge, chain
aggregation accumulate, reduce, list
advanced concat, flatten, switch, concatmap, flatmap, switchmap
timing spaceout, timeout, delay
miscellaneous action, print

Demonstration

The following example demonstrates most of the streams capabilities:

import asyncio
from aiostream import stream, pipe


async def main():

    # Create a counting stream with a 0.2 seconds interval
    xs = stream.count(interval=0.2)

    # Operators can be piped using '|'
    ys = xs | pipe.map(lambda x: x**2)

    # Streams can be sliced
    zs = ys[1:10:2]

    # Use a stream context for proper resource management
    async with zs.stream() as streamer:

        # Asynchronous iteration
        async for z in streamer:

            # Print 1, 9, 25, 49 and 81
            print('->', z)

    # Streams can be awaited and return the last value
    print('9² = ', await zs)

    # Streams can run several times
    print('9² = ', await zs)

    # Streams can be concatenated
    one_two_three = stream.just(1) + stream.range(2, 4)

    # Print [1, 2, 3]
    print(await stream.list(one_two_three))


# Run main coroutine
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
loop.close()

More examples are available in the example section of the documentation.

Contact

Vincent Michel: vxgmichel@gmail.com

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Filename, size & hash SHA256 hash help File type Python version Upload date
aiostream-0.3.1.tar.gz (20.2 kB) Copy SHA256 hash SHA256 Source None

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN SignalFx SignalFx Supporter DigiCert DigiCert EV certificate StatusPage StatusPage Status page