[R] regular expression

[Henrique Dallazuanna]

Try this also:

> grep("arg", "arg.symptom", value = TRUE, invert = TRUE)
character(0)
> grep("arg", "liver.symptom", value = TRUE, invert = TRUE)
[1] "liver.symptom"
>


On Fri, Apr 1, 2011 at 1:33 PM, array chip <arrayprofile at yahoo.com> wrote:
> Great. thank you Bernd! Learned a new thing here.
>
> John
>
>
>
>
> ________________________________
> From: Bernd Weiss <bernd.weiss at uni-koeln.de>
>
> Cc: r-help at r-project.org
> Sent: Thu, March 31, 2011 6:19:25 PM
> Subject: Re: [R] regular expression
>
> Am 31.03.2011 21:06, schrieb array chip:
>> Ok then this code didn't do what I wanted. I want "not including
>> 'arg' before '.symptom'", not individual letters of "arg", but rather
>> as a word.
>>
>> Bill Dunlap suggested using invert=T, it works for single 1
>> condition, but not for 2 conditions here: not including "arg" before
>> ".", but at the same time, does include ".symptom".
>>
>> Any other suggestions would be appreciated
>
> This does work (but I am by no means an expert in regex...). I am using
> 'negative lookbehind'[1] to define an expression like 'arg'.
>
>> grep('(?<!(arg))\\.symptom',"arg.symptom",value=T, perl = T)
> character(0)
>
>> grep('(?<!(arg))\\.symptom',"liver.symptom",value=T, perl = T)
> [1] "liver.symptom"
>
> Bernd
>
> [1] http://www.regular-expressions.info/lookaround.html
>
>        [[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