Try this where [0-9]+ matches one or more digits and $ matches the end of
string.  See http://gsubfn.googlecode.com for more.

library(gsubfn)
x <- c("v2FfaPre15", "v2FfaPre10", "v2FfaPre5", "v2Ffa2", "v2Ffa3",
"v2Ffa4")

strapply(x, "[0-9]+$", c, simplify = TRUE)


# or if you want a numeric result:
strapply(x, "[0-9]+$", as.numeric, simplify = TRUE)

On Thu, Dec 3, 2009 at 9:00 AM, oscar linares <winsaam@gmail.com> wrote:

> Dear Wiza[R]ds,
>
> I have a data.frame header that looks like this:
>
> v2FfaPre15    v2FfaPre10    v2FfaPre5    v2Ffa2    v2Ffa3    v2Ffa4
>
> I need it to look like this,
>
> 15    10    5    2    3     4
>
> i.e., with v2FfaPre and  v2Ffa stripped off
>
> Any suggestions,
>
> Thanks in advance!
>
> --
> Oscar
> Oscar A. Linares, MD
> Translational Medicine Unit
> LaPlaisance Bay, Bolles Harbor
> Monroe, Michigan 48161
>
> Department of Medicine,
> University of Toledo College of Medicine
> Toledo, OH 43606-3390
>
> Department of Internal Medicine,
> The Detroit Medical Center (DMC)
> Harper University Hospital
> Wayne State University School of Medicine
> Detroit, Michigan 48201
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> 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.
>

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