Python's standard and third-party libraries offer functions to decompress various archive types. The common formats are .gz, .tar, .tgz, .zip, and .rar.

Format Overview

• .gz (Gzip): Typically compresses a single file. It is often used in combinatino with tar for multiple files.
• .tar (Tape Archive): A Unix archival format that bundles files without compression.
• .tgz / .tar.gz: A tar archive compressed with Gzip.
• .zip: A common format that compresses multiple files individually.
• .rar: A proprietary archive format with higher compression ratios, generally slower than ZIP.

Decompressing Gzip Files (.gz)

Gzip files usual contain one item. The following function extracts a .gz file.

import gzip

def extract_gzip(gzip_path):
    """Decompresses a .gz file."""
    output_path = gzip_path.rstrip('.gz')
    with gzip.open(gzip_path, 'rb') as compressed_file:
        file_data = compressed_file.read()
    with open(output_path, 'wb') as output_file:
        output_file.write(file_data)

Extracting Tar Archives (.tar, .tgz, .tar.gz)

Tar archives can contain multiple files and directories. The tarfile module handles extraction, including compressed variants.

import tarfile
import os

def extract_tar(tar_path):
    """Extracts a tar archive, optionally compressed (e.g., .tar.gz)."""
    extract_dir = os.path.splitext(tar_path)[0] + '_extracted'
    os.makedirs(extract_dir, exist_ok=True)
    with tarfile.open(tar_path, 'r:*') as archive:
        archive.extractall(path=extract_dir)

Use 'r:*' to open archives with transparent compression detection.

Extracting ZIP Files (.zip)

The zipfile module provides functionality for ZIP archives.

import zipfile
import os

def extract_zip(zip_path):
    """Extracts a .zip archive."""
    extract_dir = os.path.splitext(zip_path)[0] + '_extracted'
    os.makedirs(extract_dir, exist_ok=True)
    with zipfile.ZipFile(zip_path, 'r') as archive:
        archive.extractall(extract_dir)

Extracting RAR Files (.rar)

RAR files require the third-party rarfile library. Install it via pip install rarfile.

import rarfile
import os

def extract_rar(rar_path):
    """Extracts a .rar archive."""
    extract_dir = os.path.splitext(rar_path)[0] + '_extracted'
    os.makedirs(extract_dir, exist_ok=True)
    with rarfile.RarFile(rar_path, 'r') as archive:
        archive.extractall(extract_dir)

Creating Tar Archives

The tarfile module also supports creating archives. The arcname parameter controls the name of the file inside the archive.

import tarfile
import os

def create_tar(source_dir, output_tar_path, compression=''):
    """Creates a tar archive from a directory."""
    # Define mode based on compression
    mode_map = {'': 'w', 'gz': 'w:gz', 'bz2': 'w:bz2'}
    mode = mode_map.get(compression, 'w')
    with tarfile.open(output_tar_path, mode) as tar:
        for root, dirs, files in os.walk(source_dir):
            for file in files:
                full_path = os.path.join(root, file)
                # Store file with its base name only
                tar.add(full_path, arcname=file)

The mode for tarfile.open() determines compression:

• 'w' or 'w:': No compression.
• 'w:gz': Gzip compression.
• 'w:bz2': Bzip2 compression.
• 'r:*': Read with automatic compression detection.