How to Compress Files Using gzip in Python Easily

To compress a file using gzip in Python, open the original file in binary read mode and a new file in gzip.open write mode, then copy the contents. The gzip module handles the compression automatically.

Syntax

Use gzip.open(filename, mode) to open a file for compression. The mode should be 'wb' for writing compressed data. Read the original file in binary mode and write to the gzip file.

• filename: The name of the gzip file to create.
• mode: Use 'wb' to write compressed data.
• Read the source file in 'rb' mode to get bytes.

python

import gzip

with open('input.txt', 'rb') as f_in:
    with gzip.open('output.txt.gz', 'wb') as f_out:
        f_out.writelines(f_in)

Example

This example compresses a text file named example.txt into example.txt.gz using the gzip module. It reads the original file in binary mode and writes the compressed data to the new file.

python

import gzip

input_file = 'example.txt'
output_file = 'example.txt.gz'

with open(input_file, 'rb') as f_in:
    with gzip.open(output_file, 'wb') as f_out:
        f_out.writelines(f_in)

print(f'File "{input_file}" compressed to "{output_file}" successfully.')

Output

File "example.txt" compressed to "example.txt.gz" successfully.

Common Pitfalls

Common mistakes when compressing files with gzip in Python include:

• Opening the source file in text mode instead of binary mode, which can cause errors or corrupted output.
• Using 'w' mode instead of 'wb' for gzip output, which will fail because gzip expects binary mode.
• Not closing files properly, which can be avoided by using with statements.

python

import gzip

# Wrong way: opening source file in text mode
# with open('input.txt', 'r') as f_in:
#     with gzip.open('output.gz', 'wb') as f_out:
#         f_out.writelines(f_in)  # This will cause an error

# Right way:
with open('input.txt', 'rb') as f_in:
    with gzip.open('output.gz', 'wb') as f_out:
        f_out.writelines(f_in)

Quick Reference

Remember these tips when compressing files with gzip in Python:

• Always open files in binary mode ('rb' for reading, 'wb' for writing).
• Use gzip.open() to write compressed files.
• Use with blocks to handle files safely and automatically close them.
• Compressed files usually have a .gz extension.

Key Takeaways

Use the gzip module's open function with 'wb' mode to write compressed files.

Always open the original file in binary mode ('rb') to avoid errors.

Use with statements to ensure files are properly closed after compression.

Compressed files typically have a .gz extension to indicate gzip format.