zpaq 0.0.2

Pure in-memory ZPAQ compression for Python (real pybind11 bindings, prebuilt wheels, no C++ toolchain needed to install).

zpaq

Pure in-memory ZPAQ compression for Python.

Every other pip install-able ZPAQ package on PyPI either shells out to the zpaq executable (which forces temp files). This package is:

• A real pybind11 binding around libzpaq (the same library the official zpaq CLI uses), wrapping abstract Reader/Writer adapters that read from and write to bytes objects with no filesystem detour.
• Distributed as prebuilt wheels for Windows, Linux and macOS across modern Python versions. No C++ toolchain needed.

Usage:

import zpaq

raw = b"hello world " * 1_000
blob = zpaq.compress(raw, level=3)   # bytes -> bytes
assert zpaq.decompress(blob) == raw

Compatibility with the zpaq CLI

zpaq.compress() emits the same on-disk format libzpaq itself writes, and zpaq.decompress() understands archives produced by the zpaq a journaling archiver (it identifies the JIDAC index/hash/info segments, discards them, and strips each data segment's trailing fragment-size footer so the recovered bytes match the original file exactly).

Tested on ten varied real files (1 KB to 25 MB, text/image/csv/jar/png/jpg/svg/exe/binary, compression levels 1-5):

Direction	Result
zpaq.compress → zpaq.decompress	10 / 10 byte-exact
zpaq.compress → official zpaq x CLI	10 / 10 byte-exact
official zpaq a CLI → zpaq.decompress	10 / 10 byte-exact

import zpaq

# Pipe to the official CLI
with open("out.zpaq", "wb") as f:
    f.write(zpaq.compress(my_bytes, level=3))
# ...later, from any machine with the zpaq executable installed:
#   $ zpaq x out.zpaq

# Read an archive that someone else produced with `zpaq a`
with open("their.zpaq", "rb") as f:
    file_bytes = zpaq.decompress(f.read())

When zpaq.decompress is fed a multi-file archive it returns the concatenated bytes of every file in the order the CLI stored them. A future release will expose a per-segment iterator API so individual files can be addressed by name.

API

Function	Description
zpaq.compress(data, level=5)	Compress a bytes-like object. level is 0..5 (0 = store, 5 = strongest). Returns bytes.
zpaq.decompress(data)	Decompress a bytes-like ZPAQ stream. Returns bytes.
zpaq.Error	Raised on any libzpaq failure (corrupt stream, bad header, ...).

Both calls release the GIL while libzpaq runs, so zpaq is friendly to threaded workloads.

License

This package is released under the same terms as the underlying libzpaq sources: public domain. See src/zpaq/vendor/COPYING.

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Not affiliated with Matt Mahoney. libzpaq was released into the public domain by its original author; this Python package wraps those sources and is an independent community project.