How to extract a gz file in python

Question

I have a .gz file, inside which there is another file. I need to extract the file inside the zipped file.

f = gzip.open(dest, 'rb')

This only opens the file but I need to download that particular file which is inside gz instead of just opening the gz file.

This question has been marked as duplicate which I accept, but I haven't found a solution where we can actually download the file and not just read its content. Same is the case with the link mentioned.

Answer 1

You could just open two files, read from the gzipped file and write to the other file (in blocks to avoid clogging the memory).

import gzip

def gunzip(source_filepath, dest_filepath, block_size=65536):
    with gzip.open(source_filepath, 'rb') as s_file, \
            open(dest_filepath, 'wb') as d_file:
        while True:
            block = s_file.read(block_size)
            if not block:
                break
            else:
                d_file.write(block)

Otherwise, you could use shutil, as suggested in How to unzip gz file using Python:

import gzip
import shutil

def gunzip_shutil(source_filepath, dest_filepath, block_size=65536):
    with gzip.open(source_filepath, 'rb') as s_file, \
            open(dest_filepath, 'wb') as d_file:
        shutil.copyfileobj(s_file, d_file, block_size)

Both solutions would work in Python 2 and 3.

Performance-wise, they are substantially equivalent, at least on my system:

%timeit gunzip(source_filepath, dest_filepath)
# 129 ms ± 1.89 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)
%timeit gunzip_shutil(source_filepath, dest_filepath)
# 132 ms ± 2.99 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)