[R] replace a whole word with sub()

[Patrick Connolly]

On Fri, 13-Nov-2009 at 03:13PM +0000, Giulio Di Giovanni wrote:

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|> Dear all, 
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|> I cannot figure out how to solve a small problem (well, not for me), surely somebody can help me in few seconds.
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|> I have a series of strings in a vector X of the type  "xxx", "yyy", "zzz", "IgA", "IgG", "kkk", "IgM", "aaa".
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|> I want to substitute every ENTIRE string beginning with "Ig" with "0".
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|> So, I'd like to have "xxx", "yyy", "zzz", "0", "0", "kkk", "0", "aaa".
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|> I can easily identify these strings with grep("^Ig", X), but if I use this criterion in the sub() function (sub("^Ig", "0", X) I obviously get "0A", "0G" etc.
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|> I didn't expect to do it in this way and I tried with metacharacters and regexps in order to grep and substitute the whole word (\b \>, $). I don't post here my tryings,  because they were obviously wrong.
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|> Please can you help me?

I think this is what you need:

> X <- c("xxx", "yyy", "zzz", "IgA", "IgG", "kkk", "IgM", "aaa")
> X[grep("^Ig", X)] <- "0"
> X
[1] "xxx" "yyy" "zzz" "0"   "0"   "kkk" "0"   "aaa"
> 

HTH

-- 
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.   
   ___    Patrick Connolly   
 {~._.~}                   Great minds discuss ideas    
 _( Y )_  	         Average minds discuss events 
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