Re: [R] position of a specific character

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Tue, 15 Jul 2008 08:57:49 +0100 (BST)

On Mon, 14 Jul 2008, Erik Iverson wrote:

> gregexpr("\\(", frg)

Better

> gregexpr("(", frg, fixed=TRUE)

(there is no regular expression here), but in this case

> which(unlist(strsplit(frg, "")) == "(")

is more efficient (especially if you want to do further manipulations on the individual characters, as Hau Li's followup seems to require).

>
>
> Hua Li wrote:
>> Hi All,
>>
>> I'm wondering whether there is a quick way to know the position of a
>> specific charcater in a long character:
>>
>> for example
>>
>> frg="((D:41.04,I:41.04):45.05,(((E:2.32,((G:0.67,J:0.67):0.44,H:1.11):1.21)"
>>
>>
>> and I would like to know that the 1st, 2nd, 26th, 27th, 28th ...
>> character is "(", is there a quick way to do that?
>>
>> Thanks!
>>
>> Hua
>>
>> ______________________________________________ R-help_at_r-project.org
>> mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do
>> read the posting guide http://www.R-project.org/posting-guide.html and
>> provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help_at_r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
Brian D. Ripley,                  ripley_at_stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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Received on Tue 15 Jul 2008 - 08:02:18 GMT

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