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The test of intelligent tinkering is to save all the parts. -- Aldo Leopold

Re: tail

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From: ros...@gmail.com (Chris Angelico)
Newsgroups: comp.lang.python
Subject: Re: tail
Date: Sun, 24 Apr 2022 21:32:11 +1000
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by: Chris Angelico - Sun, 24 Apr 2022 11:32 UTC

On Sun, 24 Apr 2022 at 21:11, Antoon Pardon <antoon.pardon@vub.be> wrote:
>
>
>
> Op 23/04/2022 om 20:57 schreef Chris Angelico:
> > On Sun, 24 Apr 2022 at 04:37, Marco Sulla<Marco.Sulla.Python@gmail.com> wrote:
> >> What about introducing a method for text streams that reads the lines
> >> from the bottom? Java has also a ReversedLinesFileReader with Apache
> >> Commons IO.
> >
> > 1) Read the entire file and decode bytes to text
> > 2) Split into lines
> > 3) Iterate backwards over the lines
> >
> > Tada! Done. And in Python, quite easy. The downside, of course, is
> > that you have to store the entire file in memory.
>
> Why not just do:
>
> tail = collections.deque(text_stream, maxlen = nr_of_lines)
> tail.reverse()
> ...
>

You still need to read the entire file, and you also restrict the max
line count, so you can't iterate this to take the next block of lines.

ChrisA

The test of intelligent tinkering is to save all the parts. -- Aldo Leopold

devel / comp.lang.python / Re: tail