fLZc 0.1.1

Python wrapper for fLZc complexity measure (based on https://github.com/lcbarnett/fLZc)

fLZc_python — Fast Lempel–Ziv Complexity for Python

A Python wrapper around the fLZc C library, implementing the original LZ76c [^1] and LZ78c [^2] versions of complexity measures (with optional normalisation) in optimized C, exposed via a clean Python API.

Features

• LZ76c & LZ78c: exact implementations of the original Lempel–Ziv algorithms
• Running complexity: compute the complexity profile along a sequence
• Dictionary output: retrieve the phrase dictionary used by the algorithm
• Normalisation: theoretical or empirical scaling factors (as in the original fLZc)
• Pure-Python API built on C for maximum speed (via ctypes)
• Works out-of-the-box on macOS & Linux; Windows support untested

Installation (Development Mode)

This project uses scikit-build-core + CMake under PEP 517.

Prerequisites

• Python 3.8–3.13
• pip, a C99-compatible compiler, and CMake ≥ 3.15
• macOS or Linux (Windows support not yet tested)

Step by step

Clone and install in editable mode:

git clone https://github.com/romybeaute/fLZc_python.git
cd fLZc_python
python -m venv .flzcvenv
source .flzcvenv/bin/activate

# clean previous builds (optional)
rm -rf build/ dist/ _skbuild/ fLZc_python/liblzc.*

# install in editable mode (builds & places the shared library)
pip install -e .

Examples & Testing

• Demo:\ fLZc_python/examples/lzc_demo.py provides an end-to-end example (including plotting).

• Unit tests:\ Run pytest tests/ to verify correctness on canonical sequences.

Implementation Details

• LZ76c follows the algorithm of Kaspar & Schuster [^3], with optional dictionary retrieval and running-profile support.
• LZ78c leverages the khashl hash-map for linear-time parsing and also supports dictionary & running outputs.
• Normalisation factors are precomputed (via MATLAB data) for alphabets up to size 10; see the original MATLAB repo for details.

Acknowledgements

Wraps the original fLZc library by Lionel Barnett (University of Sussex).

License

Distributed under the MIT License. See LICENSE for details.

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[^1]: A. Lempel and J. Ziv, On the Complexity of Finite Sequences, IEEE Trans. Info Theor. 22(1), 1976. [^2]: A. Lempel and J. Ziv, Compression of Individual Sequences via Variable-Rate Coding, IEEE Trans. Info Theor. 24(5), 1978. [^3]: F. Kaspar and H. G. Schuster, Easily calculable measure for the complexity of spatiotemporal patterns, Phys. Rev. A 36(2), 1987