regex to pickout some text between parenthesis [duplicate]

Answer 1

Here is a slightly different way, using lookbehind/ahead:

df <- "Peoplesoft(id-1290)"
regmatches(df,gregexpr("(?<=\\().*?(?=\\))", df, perl=TRUE))

Difference with Andrie's answer is that this also works to extract multiple strings in brackets. e.g.:

df <- "Peoplesoft(id-1290) blabla (foo)"
regmatches(df,gregexpr("(?<=\\().*?(?=\\))", df, perl=TRUE))

Gives:

[[1]]
[1] "id-1290" "foo"