Help with grep (and similar functions)

Try this:

library(gsubfn)
pat <- "([[:upper:]][[:lower:]]*) "
s <- "Aaaa 3 x 0 Bbbb"

strapply(s, pat, backref =-1)[[1]]

or (not quite as general but works in this case):

pat <- "([[:upper:]][[:lower:]]*) "
s <- "Aaaa 3 x 0 Bbbb"

s.idx <- gregexpr(pat, s)[[1]]
substring(s, s.idx, s.idx + attr(s.idx, "match.length") - 2)

This works:

grep("([A-Za-z]*) ", "Aaaa 3 x 0 Bbbb") # 1

This also works:

grep("([A-Za-z]*) ", "Aaaa 3 x 0 Bbbb", value=T) # Aaaa 3 x 0 Bbbb

However, I want a grep that returns the _matched_ pattern, which, in this
case, would be Aaaa. How can I do it?

Alberto Monteiro

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