Re: [R] regex question

From: Ferry <fmi.mlist_at_gmail.com>
Date: Mon, 03 Nov 2008 21:10:37 -0800

Dear John, Gabor ...

Thank you for your fast responses.
In term of efficiency, does my code efficient? I mean, I thought there is a way to combine both patterns into a single line.

Also, I tried to substitute the pattern ([ <*]+) with ([[:punct:]]), as in R regex docs:
patReg1 <- "(^[[:punct:]]+)"

but it doesn't work.

or, possibly it just my stupidity ?

On Mon, Nov 3, 2008 at 5:59 PM, John Fox <jfox_at_mcmaster.ca> wrote:
> Dear Ferry,
>
> You're almost all the way there. Just apply each substitution in turn:
>
> varReg <- "* < <* this is my text > > "
> left <- "(^[ <*]+)"
> right <- "([ > ]+$)"
> sub(right, "", sub(left, "", varReg))
> [1] "this is my text"
>
> I hope this helps,
> John
>
> ------------------------------
> John Fox, Professor
> Department of Sociology
> McMaster University
> Hamilton, Ontario, Canada
> web: socserv.mcmaster.ca/jfox
>
>
>> -----Original Message-----
>> From: r-help-bounces_at_r-project.org [mailto:r-help-bounces_at_r-project.org]
> On
>> Behalf Of Ferry
>> Sent: November-03-08 8:38 PM
>> To: r-help_at_r-project.org
>> Subject: [R] regex question
>>
>> hello,
>>
>> i am trying to extract text using regex as follows:
>>
>> "* < <* this is my text > > "
>>
>> into:
>>
>> "this is my text"
>>
>> below what I did:
>>
>> varReg <- "* < <* this is my text > > "
>>
>> ## either this pattern
>> patReg <- "(^[ <*]+)"
>> ## or below patten
>> patReg <- "([ > ]+$)"
>>
>> sub(patReg, '', varReg)
>>
>> depending of which patten I use, I could only extra the first portion
>> or the last portion of the unwanted characters. how to extract both
>> ends and keep my text "this is my text" ?
>>
>> I have tried with gsub, as below:
>> patReg <- "([ >* ]+)"
>> gsub(patReg, '', varReg)
>>
>> but it returned "thisismytext"
>>
>> any idea is appreciated.
>>
>> thanks,
>>
>> ferry
>>
>> ______________________________________________
>> 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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