Rocksolid Light

Welcome to novaBBS (click a section below)

mail  files  register  newsreader  groups  login

Message-ID:  

"The one charm of marriage is that it makes a life of deception a necessity." -- Oscar Wilde


devel / comp.lang.python / Re: iterations destroy reversed() results

SubjectAuthor
o Re: iterations destroy reversed() resultsChris Angelico

1
Re: iterations destroy reversed() results

<mailman.276.1693780975.23016.python-list@python.org>

  copy mid

https://www.novabbs.com/devel/article-flat.php?id=23957&group=comp.lang.python#23957

  copy link   Newsgroups: comp.lang.python
Path: i2pn2.org!i2pn.org!weretis.net!feeder8.news.weretis.net!fu-berlin.de!uni-berlin.de!not-for-mail
From: ros...@gmail.com (Chris Angelico)
Newsgroups: comp.lang.python
Subject: Re: iterations destroy reversed() results
Date: Mon, 4 Sep 2023 08:42:41 +1000
Lines: 24
Message-ID: <mailman.276.1693780975.23016.python-list@python.org>
References: <20230901121545.0746aa1f@pfortin.com>
<CAPTjJmrQNwyjTZ1vN2bvxo7SJM2s9F_uHsOMdf_PBaYPz+_ohQ@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
X-Trace: news.uni-berlin.de GGltQeYlFiOxfuw3XfxoUQ/dn9YnZWjhMndd2t8yr3xg==
Cancel-Lock: sha1:MstMVPuLFJznDSCt+IHYPbwKcEw= sha256:SfH4gsu7aZVF0dy/HiDKQhLFk8bhD6W71Sz+YCgzFU4=
Return-Path: <rosuav@gmail.com>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
Authentication-Results: mail.python.org; dkim=pass
reason="2048-bit key; unprotected key"
header.d=gmail.com header.i=@gmail.com header.b=S48oRoZH;
dkim-adsp=pass; dkim-atps=neutral
X-Spam-Status: OK 0.045
X-Spam-Evidence: '*H*': 0.91; '*S*': 0.00; 'this:': 0.03; '2023':
0.07; 'construct': 0.09; 'unlike': 0.09; 'chrisa': 0.16;
'from:addr:rosuav': 0.16; 'from:name:chris angelico': 0.16;
'over,': 0.16; 'sept': 0.16; 'subject:() ': 0.16; 'wrote:': 0.16;
'instead': 0.17; 'to:addr:python-list': 0.20; 'list,': 0.24;
'python-list': 0.32; 'message-id:@mail.gmail.com': 0.32; 'same':
0.34; 'header:In-Reply-To:1': 0.34; 'received:google.com': 0.34;
'fine': 0.35; 'item': 0.35; 'from:addr:gmail.com': 0.35; 'mon,':
0.36; 'using': 0.37; 'list': 0.39; 'something': 0.40; 'want':
0.40; 'should': 0.40; 'once': 0.63; 'full': 0.64; 'received:mail-
lj1-x22d.google.com': 0.69; 'longer': 0.71; 'discovered': 0.80;
'rev': 0.84; 'reversed': 0.84; 'subject:results': 0.84; 'etc...':
0.91
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=gmail.com; s=20221208; t=1693780973; x=1694385773; darn=python.org;
h=to:subject:message-id:date:from:in-reply-to:references:mime-version
:from:to:cc:subject:date:message-id:reply-to;
bh=QU34S3QvVdw/msQ+KuX8nTl5He7a9NYvNQECzps6S5g=;
b=S48oRoZHd+7KDU7ZALX7RKULtwCQOJjxB6pEW/mUwefwvbs+SB62cUf7dytsf82nid
dlfYdb4BMn3hmgU/oXj++Uta4P5AO+P9k6ebzgrhyevTGdNKYAaE8S5GKkxua/P0l06Z
x1TcTquvlG10Nu7RpWm2Mzj9L126Wfq38rCxopKu/ojgWWUtMldCmkfu81UKqc2ahHbn
qhsiqSomBkwKG+mgCjaZJZ2WwklTK/pU1IpgIuBvAH/08P6+MzcmJ9jCEDoQ5eQD42us
9yks8khsPJLw03bO5vtfj2xpt6rnTKL86taBVe48YWeQSLagMPlQ/qASig4fbLxJhrOm
VBCg==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=1e100.net; s=20221208; t=1693780973; x=1694385773;
h=to:subject:message-id:date:from:in-reply-to:references:mime-version
:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to;
bh=QU34S3QvVdw/msQ+KuX8nTl5He7a9NYvNQECzps6S5g=;
b=h0NEOWH7mpzmYhZG3pVzTPNu51A4PSY+AfK/y63SzRf3EJDGhUR3bshdPPn6NIobKL
jZfxXjewb4ghcgBOqcmbu00EefHyidp1QV4Yt4Hqg9bBZ3yEmSNqqkTNNYqat1GZZ/5F
K4ph4vNrCpUb7p9F55fiiOfeWw2mAY3V6J3lZKnwsZ7Oljy/g3iv5GrCtEgafhV3b7kk
e69xiiWKCURXA/iJUTRFClwxUHHmz3F6K9OkLIuWHm6G/IhzE6jsSN4rnGzmm5vluD8s
HIpaLjPCSJ9rIQYNz4EKW8oKqnvMJImf4xCxXAzaYyVnbEBBUvMvAaQq+knSurAQnWGN
tL2A==
X-Gm-Message-State: AOJu0YyTFRAl9Apdneg98Fd1B868H4uXulZ/wnXo7TKWYZyvKnGRknb1
eAzu84flGGdpju0VOz82g6XYqfuCotGOKWKvf6WqSkD/
X-Google-Smtp-Source: AGHT+IHUZTaU3pd60dZFWCrRG3xXauSOUgkcZ8QOKBZvwsJsLHs55b198//J6QN3WXQVl5OWnXkYSs/AcEYyiLLmaJU=
X-Received: by 2002:a05:6512:e86:b0:4fb:89b3:3373 with SMTP id
bi6-20020a0565120e8600b004fb89b33373mr6818839lfb.43.1693780972981; Sun, 03
Sep 2023 15:42:52 -0700 (PDT)
In-Reply-To: <20230901121545.0746aa1f@pfortin.com>
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.39
Precedence: list
List-Id: General discussion list for the Python programming language
<python-list.python.org>
List-Unsubscribe: <https://mail.python.org/mailman/options/python-list>,
<mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive: <https://mail.python.org/pipermail/python-list/>
List-Post: <mailto:python-list@python.org>
List-Help: <mailto:python-list-request@python.org?subject=help>
List-Subscribe: <https://mail.python.org/mailman/listinfo/python-list>,
<mailto:python-list-request@python.org?subject=subscribe>
X-Mailman-Original-Message-ID: <CAPTjJmrQNwyjTZ1vN2bvxo7SJM2s9F_uHsOMdf_PBaYPz+_ohQ@mail.gmail.com>
X-Mailman-Original-References: <20230901121545.0746aa1f@pfortin.com>
 by: Chris Angelico - Sun, 3 Sep 2023 22:42 UTC

On Mon, 4 Sept 2023 at 07:44, Pierre Fortin via Python-list
<python-list@python.org> wrote:
>
> Hi,
>
> reversed() results are fine until iterated over, after which the
> results are no longer available. This was discovered after using
> something like this:
>
> rev = reversed( sorted( list ) )
> sr = sum( 1 for _ in rev )
> # rev is now destroyed
>
> So reversed() results can only be iterated once unlike sorted(), etc...

reversed() is like iter(), and should be used the same way:

for item in reversed(list):

If you want to eagerly construct a full reversed list, instead slice the list:

list[::-1]

ChrisA

1
server_pubkey.txt

rocksolid light 0.9.8
clearnet tor