Extract numbers between brackets within a string [duplicate]

Answer 1

Here is a gsubfn solution:

library(gsubfn)

strapplyc(x, "[(](\\d+)[)]", simplify = TRUE)

[(] matches an open paren, (\\d+) matches a string of digits creating a back-reference owing to the parens around it and finally [)] matches a close paren. The back-reference is returned.