Installation

New to Python Collect? Start with the Introduction for an overview of what it does and why.

Requirements

• Python 3.13+
• No runtime dependencies

Install

Add it to your project with your dependency manager of choice:

uv add python-collect

or

pip install python-collect

Quick start

from python_collect import collect

result = (
    collect([1, 2, 3, 4, 5, 6])
    .filter(lambda n, i: n % 2 == 0)
    .map(lambda n, i: n * n)
    .sum()
)
# 56

collect()/Collection() accepts a list, a dict, another Collection, any other iterable, or None:

from python_collect import collect, Collection

numbers = collect([1, 2, 3, 4, 5])
users = collect({"alice": 30, "bob": 25})
same = Collection([1, 2, 3])

collect(range(3)).to_list()   # [0, 1, 2]
collect().to_list()           # []

Every method that returns a collection returns a new Collection, except for a handful of mutating methods (push, put, pop, shift, prepend, forget, pull, splice, transform) that change the collection in place and return self.

When you’re done chaining, pull the plain Python value back out:

collect([1, 2, 3]).map(lambda n, i: n * 2).to_list()   # [2, 4, 6]
collect({"a": 1}).all()                                 # {"a": 1}
collect([1, 2, 3]).to_json()                             # "[1, 2, 3]"

A Collection also supports the usual Python protocols (len(), in, iteration, and indexing), so you often don’t need to convert it at all.