The Reactive Extensions for Python (RxPY)

A library for composing asynchronous and event-based programs using observable collections and query operator functions in Python

ReactiveX for Python (RxPY) v4.0

For v3.X please go to the v3 branch.

RxPY v4.x runs on Python 3.7 or above. To install RxPY:

pip3 install reactivex

About ReactiveX

Reactive Extensions for Python (RxPY) is a set of libraries 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.

import rx
from rx 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 RxPY

Read the documentation to learn the principles of RxPY and get the complete reference of the available operators.

If you need to migrate code from RxPY v1.x, read the migration section.

There is also a list of third party documentation available here.

Community

Join the conversation on Slack!

The gracious folks at PySlackers have given us a home in the #rxpy Slack channel. Please join us there for questions, conversations, and all things related to RxPy.

To join, navigate the page above to receive an email invite. After signing up, join us in the #rxpy channel.

Please follow the community guidelines and terms of service.

Differences from .NET and RxJS

RxPY is a fairly complete implementation of Rx with more than 120 operators, and over 1300 passing unit-tests. RxPY is mostly a direct port of RxJS, but also borrows a bit from RxNET and RxJava in terms of threading and blocking operators.

RxPY follows PEP 8, so all function and method names are lowercase with words separated by underscores as necessary to improve readability.

Thus .NET code such as:

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

need to be written with an _ in Python:

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

With RxPY you should use named keyword arguments 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).