on 10/26/2008 10:54 AM John Lande wrote:
> dear all,
>
> I have a little problem I am doing a loop, witha grep function. sometimes it
> happens that have the following results
>
>> tmp <- grep("x", y)
>> tmp
> integer(0)
>
>
> how can I recognise this outcome? is.na is not working of course, so what
> else?
>
> thank you
A typical approach is to use any():
y <- c(letters[1:3])
> y
[1] "a" "b" "c"
> any(grep("x", y))
[1] FALSE
> any(grep("c", y))
[1] TRUE
which returns a boolean that you can then test for and proceed accordingly.
HTH,
Marc Schwartz
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