In the example below, a straight application of strsplit() is probably the
simplest solution. In a more general case where it may be desirable to match
patterns, a combination of sub() or gsub() with strsplit() might do the trick:
> x <- "Best-K Gene 11340 211952_at RANBP5 Noc= 3 - 2 LL= -963.669
-965.35"
> patt <- "Best-K Gene \\d+ (\\w+) (\\w+) Noc= \\d - (\\d) LL=
(.*)"
>
unlist(strsplit(gsub(patt,"\\1,\\2,\\3",x,perl=TRUE),","))
[1] "211952_at" "RANBP5" "2"
Alternatively, you may want to take a look at the gsubfn package - it is quite
useful. Still learning to use it myself...
> library(gsubfn)
> unlist(strapply(x,patt,function(x1,x2,x3)
c(x1,x2,x3),backref=-3,perl=TRUE))
[1] "211952_at" "RANBP5" "2"
----- Original Message ----
From: Simon Blomberg <s.blomberg1 at uq.edu.au>
To: Edward Wijaya <ewijaya at gmail.com>
Cc: r-help at r-project.org
Sent: Thursday, July 31, 2008 11:48:23 PM
Subject: Re: [R] Extract Element of String with R's Regex
How about:
unlist(strsplit(x, split=" "))[c(4:5,10)]
That perl script looks like a good reason to avoid perl.
Simon.
On Fri, 2008-08-01 at 15:13 +0900, Edward Wijaya wrote:> Hi,
>
> I have this string, in which I want to extract some of it's element:
>
> > x <- "Best-K Gene 11340 211952_at RANBP5 Noc= 3 - 2 LL=
-963.669 -965.35"
>
> yielding this array
>
> [1] "211952_at" "RANBP5" "2"
>
>
>
> In Perl we would do it this way:
>
> __BEGIN__
> my @needed =();
> my $str = "Best-K Gene 11340 211952_at RANBP5 Noc= 3 - 2 LL>
-963.669 -965.35";
> $str =~ /Best-K Gene \d+ (\w+) (\w+) Noc= \d - (\d) LL= (.*)/;
> push @needed, ($1,$2,$3);
> __END___
>
> How can we achieve this with R?
>
> - E.W.
>
> ______________________________________________
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
--
Simon Blomberg, BSc (Hons), PhD, MAppStat.
Lecturer and Consultant Statistician
Faculty of Biological and Chemical Sciences
The University of Queensland
St. Lucia Queensland 4072
Australia
Room 320 Goddard Building (8)
T: +61 7 3365 2506
http://www.uq.edu.au/~uqsblomb
email: S.Blomberg1_at_uq.edu.au
Policies:
1. I will NOT analyse your data for you.
2. Your deadline is your problem.
The combination of some data and an aching desire for
an answer does not ensure that a reasonable answer can
be extracted from a given body of data. - John Tukey.
______________________________________________
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