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From: Serhiy Storchaka <storchaka@gmail.com>
Subject: Re: fseek In Compressed Files
Date: Thu, 30 Jan 2014 17:02:58 +0200
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Xref: csiph.com comp.lang.python:65017

30.01.14 13:28, Peter Otten написав(ла):
> Ayushi Dalmia wrote:
>
>> I need to randomly access a bzip2 or gzip file. How can I set the offset
>> for a line and later retreive the line from the file using the offset.
>> Pointers in this direction will help.
>
> with gzip.open(filename) as f:
>      f.seek(some_pos)
>      print(f.readline())
>      f.seek(some_pos)
>      print(f.readline())
>
> seems to work as expected. Can you tell a bit more about your usecase (if it
> isn't covered by that basic example)?

I don't recommend to seek backward in compressed file. This is very 
inefficient operation.