[R] negation in grep

[Gabor Grothendieck]

Try

  txt[- grepl(pattern, txt)]

  txt[! grepl(pattern, txt)]


On Mon, Jun 22, 2009 at 5:45 PM, orzack<orzack at freshpond.org> wrote:
> Does anybody know how to negate a string in a grep command, i.e., what I
> need is to return only strings that do NOT contain a second string anywhere
> in the entire string.
>
>
> for
>
> txt <- c("boo","goo","doob","foo","boofoo")
>
> I need a grep command that returns strings with "oo" except when "b" is
> present anywhere. I know that
>
> grep("[^b]oo" would work to exclude "boo" and "boofoo" but not "doob"
>
> So, what I need is
>
> grep("oo + some syntax", txt)
>
> should return
>
> goo doo foo
>
> I have tried
>
>  grep("oo!boo",txt)
>
> but it returns character(0).
>
> any suggestions are much appreciated!
>
> S.
> --
> Steven Orzack
>
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