[R] backreferences in gregexpr

[Gabor Grothendieck]

On Fri, Nov 2, 2012 at 6:02 PM, Alexander Shenkin <ashenkin at ufl.edu> wrote:
> Hi Folks,
>
> I'm trying to extract just the backreferences from a regex.
>
>> temp = "abcd1234abcd1234"
>> regmatches(temp, gregexpr("(?:abcd)(1234)", temp))
> [[1]]
> [1] "abcd1234" "abcd1234"
>
> What I would like is:
> [1] "1234" "1234"
>
> Note: I know I can just match 1234 here, but the actual example is
> complicated enough that I have to match a larger string, and just want
> to pass out the backreferenced portion.
>
> Any help greatly appreciated!
>

Try this:

> library(gsubfn)
> strapplyc(temp, "abcd(1234)")
[[1]]
[1] "1234" "1234"

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