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.

Do you want this to be saved somewhere (i.e. you want basically to implement `gunzip` in Python)? — norok2, Sep 14 '18 at 13:20
Possible duplicate of [How to unzip gz file using Python](https://stackoverflow.com/questions/31028815/how-to-unzip-gz-file-using-python) — meyi, Sep 14 '18 at 13:21
@Meyi I have already checked that link. There is no answer where we can download the file in actual. Please let me know which answer you are referring to.? Thanks — S Andrew, Sep 14 '18 at 13:30
@SAndrew The link that Meyi posted shows how to unzip a .gz file. Do you actually want to do something else ? You mention download - do you mean you want to download the file from some web server ? — nos, Sep 14 '18 at 13:37
Check this link which provides an answer.
https://stackoverflow.com/questions/31028815/how-to-unzip-gz-file-using-python — Anurag A S, Sep 14 '18 at 13:38

norok2 · Accepted Answer · 2020-06-17T10:59:21.057

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)

Whats its performance compare to native `gzip` command in shell? — alper, Jul 11 '20 at 13:18
@alper probably worse, as gzip Is doing the same but essentially in C. — norok2, Jul 11 '20 at 17:09

score 1 · Answer 2 · answered Sep 14 '18 at 13:53

1

I have resolved the issue like this:

f = gzip.open(dest, 'r')
file_content = f.read()
file_content = file_content.decode('utf-8')
f_out = open('file', 'w+')
f_out.write(file_content)
f.close()
f_out.close()

dest is the file with gz

answered Sep 14 '18 at 13:53

S Andrew

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Your solution is sub-optimal as you may run into memory issues for large files. Besides, this is going to be slower than it could be, as you are performing unnecessary decoding. – norok2 Sep 14 '18 at 14:07

How to extract a gz file in python

2 Answers2