[R] A question on regular expression

[Bert Gunter]

You can't use the same regex for str_extract_all as I used for sub (or
gsub, which is what is required here)! If you do this sort of thing a lot,
you *must* learn more about regex's.

Anyway, this will do what you want I think:

z <- paste("ab{cd$ }ed", "ab{cad$ }ed", collapse = " ")  ## just for
readability

> str_extract_all(z,"\\{[^}]*\\}")
[[1]]
[1] "{cd$ }"  "{cad$ }"

Cheers,
Bert

On Thu, Sep 12, 2019 at 10:12 AM Christofer Bogaso <
bogaso.christofer using gmail.com> wrote:

> Thanks Bert,
>
> This works, but if in my text there are more than one patterns then
> fails to generate desired result.
>
> library(stringr)
> str_extract_all(paste("ab{cd$ }ed", "ab{cad$ }ed", collapse = " "),
> ".*(\\{.*\\}).*")
>
> This generates below -
>
> [[1]]
>
> [1] "ab{cd$ }ed ab{cad$ }ed"
>
> I was expecting I would get a vector of length 2 with desired pattern.
>
> Where did I make any mistake?
>
> Thanks,
>
> On Thu, Sep 12, 2019 at 10:29 PM Bert Gunter <bgunter.4567 using gmail.com>
> wrote:
> >
> > > sub(".*(\\{.*\\}).*", "\\1","ab{cd$ }ed")
> > [1] "{cd$ }"
> >
> > Use ".+" instead of ".*" within the {} if you don't want to return empty
> {}'s.
> >
> > You might wish to use the stringr package for string matching and
> manipulation, as it provides a more user friendly and consistent interface
> to these tasks.
> >
> >
> > Bert Gunter
> >
> > "The trouble with having an open mind is that people keep coming along
> and sticking things into it."
> > -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
> >
> >
> > On Thu, Sep 12, 2019 at 9:31 AM Christofer Bogaso <
> bogaso.christofer using gmail.com> wrote:
> >>
> >> Hi,
> >>
> >> I am wondering on what is the correct way to select a pattern which
> goes as -
> >>
> >> {"(any character with any length)"}
> >>
> >> The expressions " {" " and " "} " both are included in the pattern.
> >>
> >> For example, the lookup of the above pattern in the text "
> >> {"asaf455%"}57573blabla " will result in {"asaf455%"}
> >>
> >> Any help will be highly appreciated.
> >>
> >> Thanks,
> >>
> >> ______________________________________________
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>

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