ReactiveX for Python (RxPY) is a library for composing asynchronous and event-based programs using observable sequences and pipable query operators in Python. Using Rx, developers represent asynchronous data streams with Observables, query asynchronous data streams using operators, and parameterize concurrency in data/event streams using Schedulers.

.. code:: python

import reactivex as rx
from reactivex import operators as ops

source = rx.of("Alpha", "Beta", "Gamma", "Delta", "Epsilon")

composed = source.pipe(
    ops.map(lambda s: len(s)),
    ops.filter(lambda i: i >= 5)
)
composed.subscribe(lambda value: print("Received {0}".format(value)))

Learning ReactiveX

Read the documentation <https://rxpy.readthedocs.io/en/latest/>_ to learn the principles of ReactiveX and get the complete reference of the available operators.

If you need to migrate code from RxPY v1.x or v3.x, read the migration <https://rxpy.readthedocs.io/en/latest/migration.html>_ section.

There is also a list of third party documentation available here <https://rxpy.readthedocs.io/en/latest/additional_reading.html>_.

Community

Join the conversation on GitHub Discussions <https://github.com/ReactiveX/RxPY/discussions>_! if you have any questions or suggestions.

Differences from .NET and RxJS

ReactiveX for Python is a fairly complete implementation of Rx <http://reactivex.io/>_ with more than 120 operators <https://rxpy.readthedocs.io/en/latest/operators.html>, and over 1300 passing unit-tests <https://coveralls.io/github/ReactiveX/RxPY>. RxPY is mostly a direct port of RxJS, but also borrows a bit from Rx.NET and RxJava in terms of threading and blocking operators.

ReactiveX for Python follows PEP 8 <http://legacy.python.org/dev/peps/pep-0008/>_, so all function and method names are snake_cased i.e lowercase with words separated by underscores as necessary to improve readability.

Thus .NET code such as:

.. code:: c#

var group = source.GroupBy(i => i % 3);

need to be written with an _ in Python:

.. code:: python

group = source.pipe(ops.group_by(lambda i: i % 3))

With ReactiveX for Python you should use named keyword arguments <https://docs.python.org/3/glossary.html>_ instead of positional arguments when an operator has multiple optional arguments. RxPY will not try to detect which arguments you are giving to the operator (or not).

Development

This project is managed using Poetry <https://python-poetry.org/>. Code is formatted using Black <https://github.com/psf/black>, isort <https://github.com/PyCQA/isort>. Code is statically type checked using pyright <https://github.com/microsoft/pyright> and mypy <http://mypy-lang.org/>_.

If you want to take advantage of the default VSCode integration, then first configure Poetry to make its virtual environment in the repository:

.. code:: console

poetry config virtualenvs.in-project true

After cloning the repository, activate the tooling:

.. code:: console

poetry install
poetry run pre-commit install

Run unit tests:

.. code:: console

poetry run pytest

Run code checks (manually):

.. code:: console

poetry run pre-commit run --all-files

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