Hi all,
Is there a tool in base R to extract matched expressions from a
regular expression? i.e. given the regular expression "(.*?) (.*?)
([ehtr]{5})" is there a way to extract the character vector
c("one",
"two", "three") from the string "one two three" ?
Thanks,
Hadley
--
http://had.co.nz/
Is this what you want:> x <- 'xxxx xxxx one two three xxxx xxxx' > y <- sub(".*?([^[:space:]]+)[[:space:]]+([^[:space:]]+)[[:space:]]+([ehrt]{5}).*",+ "\\1 \\2 \\3", x, perl=TRUE)> unlist(strsplit(y, ' '))[1] "one" "two" "three" On Sun, Nov 8, 2009 at 1:51 PM, Hadley Wickham <hadley at rice.edu> wrote:> Hi all, > > Is there a tool in base R to extract matched expressions from a > regular expression? ?i.e. given the regular expression "(.*?) (.*?) > ([ehtr]{5})" is there a way to extract the character vector c("one", > "two", "three") from the string "one two three" ? > > Thanks, > > Hadley > > -- > http://had.co.nz/ > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >-- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve?
strapply in the gsubfn package can do that. It applies the indicated
function, here just c, to the back references from the pattern match
and then simplifies the result using simplify. (If you omit simplify
here it would give a one element list like strsplit does.)
library(gsubfn)
pat <- "(.*?) (.*?) ([ehtr]{5})"
strapply("one two three", pat, c, simplify = c)
See home page at: http://gsubfn.googlecode.com
On Sun, Nov 8, 2009 at 1:51 PM, Hadley Wickham <hadley at rice.edu>
wrote:> Hi all,
>
> Is there a tool in base R to extract matched expressions from a
> regular expression? ?i.e. given the regular expression "(.*?) (.*?)
> ([ehtr]{5})" is there a way to extract the character vector
c("one",
> "two", "three") from the string "one two
three" ?
>
> Thanks,
>
> Hadley
>
> --
> http://had.co.nz/
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>