fLZc 0.1.2

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 LZ76c¹ and LZ78c² 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 ¹, 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.

References

1. A. Lempel & J. Ziv, “On the Complexity of Finite Sequences,” IEEE Trans. Inf. Theory 22(1), 1976.
2. A. Lempel & J. Ziv, “Compression of Individual Sequences via Variable-Rate Coding,” IEEE Trans. Inf. Theory 24(5), 1978.
3. F. Kaspar & H. G. Schuster, “Easily Calculable Measure for the Complexity of Spatiotemporal Patterns,” Phys. Rev. A 36(2), 1987.