PPMd Compression Library

1.3.1 · active · verified Thu Apr 09

pyppmd is a Python wrapper for the PPMd (Prediction by Partial Matching) compression algorithm, offering both compression and decompression capabilities. It is implemented as a C-extension for performance. The current version is 1.3.1, and it receives updates periodically, primarily for maintenance, bug fixes, and minor feature enhancements.

Warnings

gotcha The PPMd8 Decoder, particularly in versions prior to 1.x, has known issues including incorrect output, wrong end-of-file (EOF) status detection, and potential deadlocks with certain parameter combinations. While improvements have been made, caution is advised.
Fix: Ensure you are on the latest version of `pyppmd`. Carefully test with your specific data and parameters. Avoid experimental or non-default `restore_method` or `endmark` options for `PPMd8Decoder` unless thoroughly validated.
breaking pyppmd requires Python 3.10 or newer. Attempting to install or use it on older Python versions will result in installation failures or runtime errors.
Fix: Upgrade your Python environment to 3.10 or later before installing `pyppmd`.
gotcha While pyppmd generally handles data streams, the `compress` and `decompress` methods are designed for single-shot operations with complete byte strings. Using them incrementally or with partial data without careful state management may lead to corruption or errors.
Fix: Provide complete byte strings to `compress` and `decompress` methods. For streaming scenarios, consider buffering data or implementing higher-level stream processing on top of `pyppmd`'s block-wise operations.

Install

pip install pyppmd Install latest version

Imports

PPMdEncoder
```
from pyppmd import PPMdEncoder
```
PPMdDecoder
```
from pyppmd import PPMdDecoder
```

Quickstart

This quickstart demonstrates the basic usage of pyppmd to compress and decompress a byte string. It initializes an `Encoder` and `Decoder`, processes data, and then verifies the integrity of the decompressed output.

import pyppmd

# Prepare some data
original_data = b"This is a test string to be compressed multiple times. " * 100

# Initialize encoder and decoder
encoder = pyppmd.PPMdEncoder()
decoder = pyppmd.PPMdDecoder()

# Compress the data
compressed_data = encoder.compress(original_data)
print(f"Original size: {len(original_data)} bytes")
print(f"Compressed size: {len(compressed_data)} bytes")

# Decompress the data
decompressed_data = decoder.decompress(compressed_data)

# Verify decompression
assert original_data == decompressed_data
print("Decompression successful and data matches original!")

view raw JSON →