[R] regular expression help

[William Dunlap]

You can use parentheses to factor out the common string in David's
pattern, as in
   grep(value=TRUE, "(^|//|[[:space:]]+)AARSD1($|//|[[:space:]]+)", test)

(By 'whitespace' I could not tell if you meant any amount of
whitespace or a single
whitespace character.  I use '+' to match one or more whitespace characters.)

Bill Dunlap
TIBCO Software
wdunlap tibco.com


On Thu, Jun 26, 2014 at 10:12 PM, David Winsemius
<dwinsemius at comcast.net> wrote:
>
> On Jun 26, 2014, at 6:11 PM, C Lin wrote:
>
>> Hi Duncan,
>>
>> Thanks for trying to help. Sorry for not being clear.
>> The string I'd like to get is 'AARSD1'
>> It can be followed or preceded by white space or // or nothing
>>
>> so, from test <- c('AARSD11','AARSD1-','AARSD1//','AARSD1 //','//AARSD1','AARSD1');
>>
>> I want to match only 'AARSD1//','AARSD1 //','//AARSD1','AARSD1'
>
> Perhaps you want jsut
>
> grepl('^AARSD1//$|^AARSD1 //$|^//AARSD1$|^AARSD1', test)
>
>> grepl('^AARSD1//$|^AARSD1 //$|^//AARSD1$|^AARSD1$', test)
> [1] FALSE FALSE  TRUE  TRUE  TRUE  TRUE
>
> --
> David.
>
>>
>
>> Thanks,
>> Lin
>>
>> ----------------------------------------
>>> From: dulcalma at bigpond.com
>>> To: baccts at hotmail.com; r-help at r-project.org
>>> Subject: RE: [R] regular expression help
>>> Date: Fri, 27 Jun 2014 10:59:29 +1000
>>>
>>> Hi
>>>
>>> You only have a vector of length 5 and I am not quite sure of the string you
>>> are testing
>>> so try this
>>>
>>> grep('[/]*\\<AARSD1\\>[/]*',test)
>>>
>>> Duncan
>>>
>>> Duncan Mackay
>>> Department of Agronomy and Soil Science
>>> University of New England
>>> Armidale NSW 2351
>>> Email: home: mackay at northnet.com.au
>>>
>>> -----Original Message-----
>>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
>>> Behalf Of C Lin
>>> Sent: Friday, 27 June 2014 10:05
>>> To: r-help at r-project.org
>>> Subject: [R] regular expression help
>>>
>>> Dear R users,
>>>
>>> I need to match a string. It can be followed or preceded by whitespace or //
>>> or nothing.
>>> How do I code it in R?
>>>
>>> For example:
>>> test <- c('AARSD11','AARSD1-','AARSD1//','AARSD1 //','//AARSD1');
>>> grep('AARSD1(\\s*//*)',test);
>>>
>>> should return 3,4,5 and 6.
>>>
>>
>
>
> David Winsemius
> Alameda, CA, USA
>
> ______________________________________________
> 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.