[R] Regular expression to find value between brackets

[Matt Shotwell]

Here's a shorter (but more cryptic) one:

> gsub("^([^\\(]+)(\\((.+)\\))?", "\\2", tests)
[1] ""        "(%)"     "(%)"     "(mg/ml)"

> gsub("^([^\\(]+)(\\((.+)\\))?", "\\3", tests)
[1] ""      "%"     "%"     "mg/ml"

-Matt


On Wed, 2010-10-13 at 14:34 -0400, Henrique Dallazuanna wrote:
> Try this:
> 
> replace(gsub(".*\\((.*)\\)$", "\\1", tests), !grepl("\\(.*\\)", tests), "")
> 
> 
> On Wed, Oct 13, 2010 at 3:16 PM, Bart Joosen <bartjoosen at hotmail.com> wrote:
> 
> >
> > Hi,
> >
> > this should be an easy one, but I can't figure it out.
> > I have a vector of tests, with their units between brackets (if they have
> > units).
> > eg tests <- c("pH", "Assay (%)", "Impurity A(%)", "content (mg/ml)")
> >
> > Now I would like to hava a function where I use a test as input, and which
> > returns the units
> > like:
> > f <- function (x) sub("\\)", "", sub("\\(", "",sub("[[:alnum:]]+","",x)))
> > this should give "", "%", "%", "mg/ml", but it doesn't do the job quit
> > well.
> >
> > After searching in the manual, and on the help lists, I cant find the
> > answer.
> >
> > anyone?
> >
> > Bart
> > --
> > View this message in context:
> > http://r.789695.n4.nabble.com/Regular-expression-to-find-value-between-brackets-tp2994166p2994166.html
> > Sent from the R help mailing list archive at Nabble.com.
> >
> > ______________________________________________
> > 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.
> >
> 
> 
> 

-- 
Matthew S. Shotwell
Graduate Student 
Division of Biostatistics and Epidemiology
Medical University of South Carolina