R help - Nov 2010 - regular exprs

Dear All,

I would appreciate any help with the following: given the vector 'x'

x <- c("Ass1", "Ass.s1", "Ass2",
"Ass.s2")

I would like to pick up the positions where the character string 
contains "Ass" but does not contain "Ass.s", so for
'x' that would be
positions 1 and 3.

I guess this could be programmed around grep() using a suitable regular 
expression, but I haven't managed to succeed.

Thanks in advance.

Best,
Dimitris

--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center

Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
Web: http://www.erasmusmc.nl/biostatistiek/

On Nov 7, 2010, at 10:15 AM, Dimitris Rizopoulos wrote:
> Dear All,
>
> I would appreciate any help with the following: given the vector
'x'
>
> x <- c("Ass1", "Ass.s1", "Ass2",
"Ass.s2")
>
> I would like to pick up the positions where the character string  
> contains "Ass" but does not contain "Ass.s", so for
'x' that would
> be positions 1 and 3.
 > x[ grepl("Ass", x) & !grepl("Ass\\.s", x) ]
[1] "Ass1" "Ass2"

HTH;
-- 
David
>
> I guess this could be programmed around grep() using a suitable  
> regular expression, but I haven't managed to succeed.
>
> Thanks in advance.
>
> Best,
> Dimitris
>
> --
> Dimitris Rizopoulos
> Assistant Professor
David Winsemius, MD
West Hartford, CT

Try this:

grep("Ass[^\\.]", x)


On Sun, Nov 7, 2010 at 1:15 PM, Dimitris Rizopoulos <
d.rizopoulos@erasmusmc.nl> wrote:
> Dear All,
>
> I would appreciate any help with the following: given the vector
'x'
>
> x <- c("Ass1", "Ass.s1", "Ass2",
"Ass.s2")
>
> I would like to pick up the positions where the character string contains
> "Ass" but does not contain "Ass.s", so for 'x'
that would be positions 1 and
> 3.
>
> I guess this could be programmed around grep() using a suitable regular
> expression, but I haven't managed to succeed.
>
> Thanks in advance.
>
> Best,
> Dimitris
>
> --
> Dimitris Rizopoulos
> Assistant Professor
> Department of Biostatistics
> Erasmus University Medical Center
>
> Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
> Tel: +31/(0)10/7043478
> Fax: +31/(0)10/7043014
> Web: http://www.erasmusmc.nl/biostatistiek/
>
> ______________________________________________
> R-help@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

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On Sun, Nov 7, 2010 at 10:15 AM, Dimitris Rizopoulos
<d.rizopoulos at erasmusmc.nl> wrote:
> Dear All,
>
> I would appreciate any help with the following: given the vector
'x'
>
> x <- c("Ass1", "Ass.s1", "Ass2",
"Ass.s2")
>
> I would like to pick up the positions where the character string contains
> "Ass" but does not contain "Ass.s", so for 'x'
that would be positions 1 and
> 3.
>
> I guess this could be programmed around grep() using a suitable regular
> expression, but I haven't managed to succeed.
>
Assuming that "Ass" appears at most once in each string, as in the
example:
> x <- c("Ass1", "Ass.s1", "Ass2",
"Ass.s2", "Ass.")
> grep("Ass(?![.]s)", x, perl = TRUE)
[1] 1 3 5

See ?regex for more info.  There is also regular expression links in
the Links box at http://gsubfn.googlecode.com .

-- 
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GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com