[R] pattern matching

Duncan Murdoch murdoch at stats.uwo.ca
Sun Oct 26 20:06:05 CET 2008

On 26/10/2008 11:54 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?

length(integer(0)) is zero.  If you get any matches, you'll get a longer 

Duncan Murdoch

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