R help - Oct 1999 - if(grep())

On Tue, 12 Oct 1999, Michael Lapsley wrote:
> Would anyone care to comment if this is the best solution to this problem?
> 
> > trygrep <-function(x,y)
> + if(grep(x,y))
> + print("yes") else
> + print("NO")
> >  
> >trygrep("foo","bafoobar")
> [1] "yes"
> >
> > trygrep("foo","bar")
> Error in if (grep(x, y)) print("yes") else print("NO")
: missing value where
> logical needed

You could try 
	if(length(grep(x,y))==0)



Thomas Lumley
Assistant Professor, Biostatistics
University of Washington, Seattle

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Would anyone care to comment if this is the best solution to this problem?
> trygrep <-function(x,y)
+ if(grep(x,y))
+ print("yes") else
+ print("NO")
>  
>trygrep("foo","bafoobar")
[1] "yes"
>
> trygrep("foo","bar")
Error in if (grep(x, y)) print("yes") else print("NO") :
missing value where
logical needed

My solution:
> trygrep <-function(x,y)
+ if(!is.na(grep(x,y)[1]))
+ print("yes") else
+ print("NO")
>
> trygrep("foo","bafoobar")
[1] "yes"
> trygrep("foo","bar")
[1] "NO"
> 
Regards,

Michael

This is not exactly intuitive and it took me ages to get past what should be a
very simple couple of lines.

Am I missing something more obvious?  I'm sure that if I need to do this
in 6 months time I'm not going to remember how I did it!

----------------------------------
E-Mail: Michael Lapsley <mlapsley at ndirect.co.uk>
Date: 12-Oct-99
Time: 00:04:03

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