R help - Apr 2009 - list substring

hi
I ve a list of item x = ( "xxxxx1"
                               "xxxxx2"
                               "yyyyx3")

I need to extract a new vector y  = ( "xxxx",
                                                   "xxxx",
                                                   "yyyy"
)
I mean, for each item I need to extract the first 4 digit
How is that possible?

Thank you
                             
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Dear celpeda,
Try this:
 x = c( "xxxxx1", "xxxxx2", "yyyyx3")
substr(x,1,4)
[1] "xxxx" "xxxx" "yyyy"

See ?substr for more details.

HTH,

Jorge


On Wed, Apr 1, 2009 at 9:30 AM, calpeda <mauro.biasolo@calpeda.it> wrote:
>
> hi
> I ve a list of item x = ( "xxxxx1"
>                               "xxxxx2"
>                               "yyyyx3")
>
> I need to extract a new vector y  = ( "xxxx",
>                                                   "xxxx",
>                                                   "yyyy"
> )
> I mean, for each item I need to extract the first 4 digit
> How is that possible?
>
> Thank you
>
> --
> View this message in context:
> http://www.nabble.com/list-substring-tp22826435p22826435.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.
>
	[[alternative HTML version deleted]]

try this:

x <- c("xxxxx1", "xxxxx2", "yyyyx3")
substr(x, 1, 4)


Best,
Dimitris


calpeda wrote:
> hi
> I ve a list of item x = ( "xxxxx1"
>                                "xxxxx2"
>                                "yyyyx3")
> 
> I need to extract a new vector y  = ( "xxxx",
>                                                    "xxxx",
>                                                    "yyyy"
> )
> I mean, for each item I need to extract the first 4 digit
> How is that possible?
> 
> Thank you
>                              
-- 
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

calpeda wrote:
> hi
> I ve a list of item x = ( "xxxxx1"
>                                "xxxxx2"
>                                "yyyyx3")
>
> I need to extract a new vector y  = ( "xxxx",
>                                                    "xxxx",
>                                                    "yyyy"
> )
> I mean, for each item I need to extract the first 4 digit
> How is that possible?
>   
    sub('^(\\d{4}).*', '\\1', x, perl=TRUE)

vQ