From: Henrique Dallazuanna <wwwhsd_at_gmail.com>

Date: Mon, 31 May 2010 14:07:06 -0300

Date: Mon, 31 May 2010 14:07:06 -0300

My mistake:

"\\1" is a backreference - see replacement argument in ?gsub.

This work:

gsub("(.*) MIMA.*", "\\1", desc)

On Mon, May 31, 2010 at 2:00 PM, Juliet Hannah <juliet.hannah_at_gmail.com>wrote:

> What is the meaning of "\\1" here? Thanks.

*>
**> desc <- c("hsa-let-7a MIMAT0000062 Homo sapiens let-7a","hsa-let-7a*
**> MIMAT0004481 Homo sapiens let-7a*","hsa-let-7a-2* MIMAT0010195 Homo
**> sapiens let-7a-2*")
**>
**> I'm missing something:
**>
**> > gsub(" MIMA.*", "\\1", desc)
**> [1] "hsa-let-7a" "hsa-let-7a*" "hsa-let-7a-2*"
**> > gsub(" MIMA.*", "\\2", desc)
**> [1] "hsa-let-7a" "hsa-let-7a*" "hsa-let-7a-2*"
**> > gsub(" MIMA.*", "\\3", desc)
**> [1] "hsa-let-7a" "hsa-let-7a*" "hsa-let-7a-2*"
**>
**> On Thu, May 27, 2010 at 10:58 AM, Henrique Dallazuanna <wwwhsd_at_gmail.com>
**> wrote:
**> > Try this:
**> >
**> > gsub(" MIMA.*", "\\1", desc)
**> >
**> > On Thu, May 27, 2010 at 11:37 AM, <mauede_at_alice.it> wrote:
**> >
**> >> I have the following vector of strings (shown only the first 3 elements)
**> >>
**> >> > desc[1:3]
**> >> [1] "hsa-let-7a MIMAT0000062 Homo sapiens let-7a"
**> >> [2] "hsa-let-7a* MIMAT0004481 Homo sapiens let-7a*"
**> >> [3] "hsa-let-7a-2* MIMAT0010195 Homo sapiens let-7a-2*"
**> >> > is.vector(desc)
**> >> [1] TRUE
**> >> > A <- unlist(strsplit(desc[1:3], " "))
**> >> > A
**> >> [1] "hsa-let-7a MIMAT0000062 Homo sapiens let-7a"
**> >> [2] "hsa-let-7a* MIMAT0004481 Homo sapiens let-7a*"
**> >> [3] "hsa-let-7a-2* MIMAT0010195 Homo sapiens let-7a-2*"
**> >> > as.vector(A)
**> >> [1] "hsa-let-7a MIMAT0000062 Homo sapiens let-7a"
**> >> [2] "hsa-let-7a* MIMAT0004481 Homo sapiens let-7a*"
**> >> [3] "hsa-let-7a-2* MIMAT0010195 Homo sapiens let-7a-2*"
**> >> >
**> >> I would like to extract only the first field (of variable length). That
**> is
**> >> I need a vector containing
**> >> "hsa-let-7a "
**> >> "hsa-let-7a*"
**> >> "hsa-let-7a-2*"
**> >>
**> >> The operator [[]][] works only on the single vector element. I would
**> like
**> >> to extract the 1st field
**> >> with one single instruction rather than a loop as traditional
**> programming
**> >> languages request.
**> >>
**> >> Thank you in advance for you help.
**> >> Maura
**> >>
**> >>
**> >>
**> >> tutti i telefonini TIM!
**> >>
**> >>
**> >> [[alternative HTML version deleted]]
**> >>
**> >> ______________________________________________
**> >> 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.
**> >>
**> >
**> >
**> >
**> > --
**> > Henrique Dallazuanna
**> > Curitiba-Paraná-Brasil
**> > 25° 25' 40" S 49° 16' 22" O
**> >
**> > [[alternative HTML version deleted]]
**> >
**> >
**> > ______________________________________________
**> > 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.
**> >
**> >
**>
*

-- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O [[alternative HTML version deleted]]Received on Mon 31 May 2010 - 17:09:38 GMT______________________________________________ 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.

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