polyleven

library0.11.0pypypi✓ verified 25d ago

Polyleven is a hyper-fast Python library for computing Levenshtein distance, implemented in C for optimal performance. It is designed to be efficient for comparing both short and long string inputs, is stand-alone with no external Python dependencies, and is distributed under the MIT License. The current version is 0.11.0, released on February 9, 2026, indicating an active release cadence.

data

pip install polyleven

github ↗package ↗

INSTALL

IMPORT

SIG · POLYLEVEN

polyleven

datapythonv0.11.0

Install

1.7s avg

Import

—

Disk

16MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.11.0 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.000s · 17.8MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 1.7s · import 0.000s · 18MB

16MB installed

● package 16MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

levenshtein

✓ from polyleven import levenshtein

This quickstart demonstrates how to import the `levenshtein` function and use it to calculate the Levenshtein distance between two strings. It also shows how to leverage the optional `max_threshold` argument to improve performance, especially when only interested in distances below a certain value.

from polyleven import levenshtein # Calculate Levenshtein distance between two strings distance1 = levenshtein('kitten', 'sitting') print(f"Distance between 'kitten' and 'sitting': {distance1}") # Calculate Levenshtein distance with a maximum threshold for efficiency # If the actual distance exceeds the threshold, the threshold + 1 is returned. distance2 = levenshtein('apple', 'aple', 1) # Actual distance is 1 print(f"Distance between 'apple' and 'aple' with max_threshold=1: {distance2}") distance3 = levenshtein('banana', 'orange', 2) # Actual distance is higher than 2 print(f"Distance between 'banana' and 'orange' with max_threshold=2: {distance3}") assert distance1 == 3 assert distance2 == 1 assert distance3 == 3 # Returns threshold + 1 because actual distance > threshold

Debug

Known issues

gotchaFor optimal performance, especially with long strings or when only interested in small distances, provide an integer `k` as the third argument to the `levenshtein()` function. This `max_threshold` limits the maximum distance computed, making the operation significantly more efficient. If the true distance exceeds `k`, the function returns `k + 1`.

fix

Call `levenshtein('string1', 'string2', k=max_threshold)` where `max_threshold` is the maximum relevant distance. For example, `levenshtein('abcde', 'xxxxx', 2)` would return `3` as the actual distance (5) is greater than the threshold (2).

affects: All versions

gotchaThe license for Polyleven changed from Public Domain to MIT License starting from version 0.7. Users of older versions relying on Public Domain terms should be aware of this change.

fix

Verify the license (MIT for v0.7+) to ensure compatibility with your project's licensing requirements. If strict adherence to Public Domain is necessary, ensure usage of versions prior to 0.7.

affects: Prior to 0.7 (Public Domain); 0.7 and later (MIT License)

gotchaWhile the `max_threshold` argument generally improves performance, the speed boost is most noticeable when the threshold `k` is small, typically less than 3. Larger thresholds still offer some benefit but diminish as `k` approaches the full string length.

fix

When designing for maximum performance and a small distance is expected or acceptable, prioritize using a `max_threshold` value of 1 or 2.

affects: All versions

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'polyleven'

The 'polyleven' library is not installed in your current Python environment or the Python interpreter cannot find it.

fix

Install the library using pip: `pip install polyleven`

ImportError: cannot open shared object file: No such file or directory

This error typically occurs when the C extension part of 'polyleven' cannot be loaded, often due to missing system dependencies (like C/C++ runtime libraries) or an incomplete/corrupted installation, especially on Linux systems.

fix

Ensure your system has the necessary build tools and C/C++ runtime libraries. Try reinstalling 'polyleven' in a clean environment: `pip uninstall polyleven` then `pip install polyleven`. If on Linux, ensure `gcc` and `g++` are installed, and consider updating system libraries.

AttributeError: module 'polyleven' has no attribute 'levenshteinn'

You are attempting to call a function or access an attribute named 'levenshteinn' which does not exist in the 'polyleven' module. This is likely a typo.

fix

The correct function name for calculating Levenshtein distance is `levenshtein`. Correct your code to `from polyleven import levenshtein` and use `levenshtein(str1, str2)`.

TypeError: levenshtein() takes at most 3 arguments (4 given)

The `levenshtein` function was called with more arguments than it expects. It accepts two strings and an optional integer threshold argument.

fix

Review your function call and provide only two string arguments (the strings to compare) and an optional third integer argument for the maximum distance threshold, e.g., `levenshtein('string1', 'string2')` or `levenshtein('string1', 'string2', max_distance_int)`.

Upgrade

Version history

0.11.0latest on PyPI · released Feb 9, 2026

Audit

Dependencies

No dependency data recorded yet.

Agent activity

7 hits · last 30 days

node

Resources

githubhttps://github.com/fujimotos/polyleven ↗

packagehttps://pypi.org/project/polyleven/ ↗