Orderly Set

5.5.0 · active · verified Sat Mar 28

Orderly Set is a Python package providing several implementations of ordered set data structures, including `OrderlySet`, `StableSet`, `StableSetEq`, `OrderedSet`, and `RoughMaxSizeSet`. These implementations combine the uniqueness of a set with the order-preserving characteristics of a list or sequence, offering various performance trade-offs for operations such as insertion, deletion, membership testing, and index lookups. The library is actively maintained, with its current version being 5.5.0, and receives regular updates as evidenced by its GitHub release history.

Warnings

breaking Version 5.4.0 changed behavior for accessing multiple items, switching from a singular `index` method to `indexes` for iterable input. Code using `index` for multiple items may break.
Fix: Review calls to `.index()` when attempting to retrieve multiple item indices. The documentation (or source) suggests `__getitem__()` and `index()` methods were extended to accept iterables for 'fancy indexing'.
gotcha There are several 'ordered set' libraries on PyPI (e.g., `orderedset` by simonpercivall, `ordered-set` by rspeer). Ensure you are importing from `orderly_set` as `from orderly_set import ...` to use this specific library.
Fix: Always use `from orderly_set import [ClassName]` for `orderly-set`. If you intend to use a different library, verify its specific import path.
gotcha The `OrderedSet` class within `orderly-set` has O(N) deletion performance, which can be a bottleneck for applications with frequent deletions on large sets.
Fix: For deletion-heavy workloads where insertion order must be maintained, consider `StableSet` which offers O(1) deletion, or evaluate if a standard `set` (unordered) or Python's built-in `dict` keys (ordered since 3.7 but without list-like indexing) might be more suitable.
gotcha The `StableSet` class within `orderly-set` has O(N) index lookup performance.
Fix: If frequent lookups by index are critical, `OrderedSet` offers O(1) index lookup. Choose the implementation (`OrderedSet`, `StableSet`, etc.) that best fits your performance requirements for specific operations.

Install

pip install orderly-set Install latest version

Imports

OrderedSet
```
from orderly_set import OrderedSet
```
Beware of other 'ordered set' libraries on PyPI with similar names but different import paths and implementations.
StableSet
```
from orderly_set import StableSet
```
RoughMaxSizeSet
```
from orderly_set import RoughMaxSizeSet
```
OrderlySet
```
from orderly_set import OrderlySet
```
Note the capitalization: `OrderlySet` is a specific class within the `orderly_set` package, distinct from `OrderedSet`.

Quickstart

This quickstart demonstrates the creation and basic operations of `OrderedSet` and `StableSet`. `OrderedSet` acts like a hybrid of a list and a set, preserving insertion order with efficient index lookup but O(N) deletion. `StableSet` provides fast O(1) insertion, deletion, and membership testing, but O(N) index lookup.

from orderly_set import OrderedSet, StableSet

# Using OrderedSet
letters = OrderedSet('abracadabra')
print(f"OrderedSet: {letters}")  # Expected: OrderedSet(['a', 'b', 'r', 'c', 'd'])
print(f"'r' in letters: {'r' in letters}")
print(f"Index of 'r': {letters.index('r')}")
print(f"Item at index 2: {letters[2]}")
letters.add('x')
print(f"After adding 'x': {letters}")

# Using StableSet (different performance characteristics)
stable_items = StableSet([1, 5, 2, 5, 3])
print(f"StableSet: {stable_items}") # Expected: StableSet({1, 5, 2, 3})
stable_items.add(4)
print(f"After adding 4: {stable_items}")

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