[R] Regular expression to find value between brackets

[Bert Gunter]

Note:

My original proposal, not quite right, can be made quite right via:

gsub(".*\\((.*)\\).*||[^()]+", "\\1",tests)

The "||" or clause at the end handles the case where there are no
parentheses in the string.

-- Bert

On Wed, Oct 13, 2010 at 11:16 AM, 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
> --
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-- 
Bert Gunter
Genentech Nonclinical Biostatistics