pyppmd

PyPPMd

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Introduction

pyppmd module provides classes and functions for compressing and decompressing text data, using PPM(Prediction by partial matching) compression algorithm which has several variations of implementations. PPMd is the implementation by Dmitry Shkarin. PyPPMD use Igor Pavlov's range coder introduced in 7-zip.

The API is similar to Python's bz2/lzma/zlib module.

Some parts of th codes are derived from 7-zip, pyzstd and ppmd-cffi.

Development status

A project status is considered as Stable.

Extra input byte

PPMd algorithm and implementation is designed to use Extra input byte. The encoder will omit a last null (b"\0") byte when last byte is b"\0". You may need to provide an extra null byte when you don't get expected size of extracted data.

You can do like as:

.. code-block::

dec = pyppmd.Ppmd7Decoder(max_order=6, mem_size=16 << 10)
result = dec.decode(compressed, length)
if len(result) < length:
    if dec.needs_input:
        # ppmd need an extra null byte
        result += dec.decode(b"\0", length - len(result))
    else:
        result += dec.decode(b"", length - len(result))

.. warning:: When use it on MSYS2/MINGW64 environment, you should set environment variable SETUPTOOLS_USE_DISTUTILS=stdlib

Copyright and License

Some codes are derived from p7zip/7zip and pyzstd project. Details are shown in LicenseNotices.rst

• SPDX-License-Identifier: LGPL-2.1-or-later
• SPDX-URL: https://spdx.org/licenses/LGPL-2.1-or-later.html

PyPPMd is licensed under GNU Lesser General Public License v2.1 or later.

• Copyright (C) 2020-2023 Hiroshi Miura
• Copyright (C) 2020-2021 Ma Lin
• Copyright (C) 2010-2012 Lockless Inc.
• Copyright (C) 1999-2017 Igor Pavlov

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA