[R] Regular expression to find value between brackets

[Bart Joosen]

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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