Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!newsreader4.netcologne.de!news.netcologne.de!newsfeed.freenet.ag!news2.euro.net!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Date: Fri, 19 Jul 2013 17:44:24 -0400
From: Devyn Collier Johnson <devyncjohnson@gmail.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130623 Thunderbird/17.0.7
MIME-Version: 1.0
To: Python Mailing List <python-list@python.org>
Subject: Re: Find and Replace Simplification
References: <mailman.4865.1374240179.3114.python-list@python.org> <51e967bb$0$29971$c3e8da3$5496439d@news.astraweb.com>
In-Reply-To: <51e967bb$0$29971$c3e8da3$5496439d@news.astraweb.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: list
Newsgroups: comp.lang.python
Message-ID: <mailman.4884.1374270271.3114.python-list@python.org>
Lines: 65
NNTP-Posting-Host: 2001:888:2000:d::a6
Xref: csiph.com comp.lang.python:50922


On 07/19/2013 12:22 PM, Steven D'Aprano wrote:
> On Fri, 19 Jul 2013 09:22:48 -0400, Devyn Collier Johnson wrote:
>
>> I have some code that I want to simplify. I know that a for-loop would
>> work well, but can I make re.sub perform all of the below tasks at once,
>> or can I write this in a way that is more efficient than using a
>> for-loop?
>>
>> DATA = re.sub(',', '', 'DATA')
>> DATA = re.sub('\'', '', 'DATA')
>> DATA = re.sub('(', '', 'DATA')
>> DATA = re.sub(')', '', 'DATA')
>
> I don't think you intended to put DATA in quotes on the right hand side.
> That makes it literally the string D A T A, so all those replacements are
> no-ops, and you could simplify it to:
>
> DATA = 'DATA'
>
> But that's probably not what you wanted.
>
> My prediction is that this will be by far the most efficient way to do
> what you are trying to do:
>
> py> DATA = "Hello, 'World'()"
> py> DATA.translate(dict.fromkeys(ord(c) for c in ",'()"))
> 'Hello World'
>
> That's in Python 3 -- in Python 2, using translate will still probably be
> the fastest, but you'll need to call it like this:
>
> import string
> DATA.translate(string.maketrans("", ""), ",'()")
>
> I also expect that the string replace() method will be second fastest,
> and re.sub will be the slowest, by a very long way.
>
> As a general rule, you should avoiding using regexes unless the text you
> are searching for actually contains a regular expression of some kind. If
> it's merely a literal character or substring, standard string methods
> will probably be faster.
>
>
> Oh, and a tip for you:
>
> - don't escape quotes unless you don't need to, use the other quote.
>
> s = '\''  # No, don't do this!
> s = "'"  # Better!
>
> and vice versa.
>
>
>
>
Thanks for finding that error; DATA should not be in quotes. I cannot 
believe I missed that. Good eye Steven!

Using the replace command is a brilliant idea; I will implement that 
where ever I can. I am wanting to perform all of the replaces at once. 
Is that possible?

Mahalo,
DCJ