On Sep 15, 2010, at 10:16 AM, raje...@cse.iitm.ac.in wrote:
>
> Hi,
>
> I need to check if a string "<rh>a,b,c,d<rh>" is delimited by two "<rh>" 's
> as efficiently as possible(I need to do this a lot of times) and return TRUE.
> Can someone suggest a good technique?
See ?grep and ?regex
> grepl("^<rh>.*<rh>$", "<rh>a,b,c,d<rh>")
[1] TRUE
You can pass the entire source vector to grepl():
Vec <- c("<rh>a,b,c,d<rh>", "1, 2, 3, 4", "a, b, c, d<rh>", "<rh>1, 2, 3,
4<rh>")
> grepl("^<rh>.*<rh>$", Vec)
[1] TRUE FALSE FALSE TRUE
HTH,
Marc Schwartz
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