zran 0.0.2

Utility for randomly accessing DEFLATE-compressed data

ZRAN

Random read access for gzip and zip files

Description

zran is a Python extension that wraps the zran library, which was created by Mark Adler (the creator of zlib). This utility allows you to create an index that allows you begin decompressing DEFLATE-compressed data (ZLIB, GZIP, or DEFLATE format) from compression block boundaries. This effectively allows you to randomly access DEFLATE-compressed data once the index is created.

Installation

In your preferred python environment:

git clone https://github.com/forrestfwilliams/zran.git
cd zran
python -m pip install .

As far as I can tell, pip installing with the --editable command is not valid when the code needs to be compiled, so you will need to re-install the package if you make any changes.

Usage

To use zran, you need to:

1. Create an index for a compressed file
2. Save this index
3. Use this index to access the data on subsequent reads

To create and save the index:

import zran

with open('compressed.gz', 'rb') as f:
    compressed_file = f.read()
    index = zran.Index.create_index(compressed_file)

This Index can be written to a file (index.to_file('index.dflidx')), or directly passed to zran.deompress:

start = 1000
length = 2000
data = zran.decompress(compressed_file, index, start, length)

That's it!