[R] Finding a single unique item in duplicated vectors

[Charles C. Berry]

On Wed, 4 Apr 2007, John Kane wrote:

> I have a very simple problem and am completely missing
> the solution.
> I have two character variables (character ID's from
> two datasets) Data set 'b'
> is data set 'a' with one more subject added.
> How do I find out which is the added subject?


 	setdiff( b, a ) ??

>
> I have tried duplicated and unique without much
> success.  I can find all the
> duplicated ID's but how do I extract the new "unique"
> one?
> Example:
> a  <-  as.character(Cs(b,d,c,a))
> b  <- as.character( Cs(a,b,c,d,e))
> h  <- c(a,b) ; h
> h[duplicated(h)]
>
> I just want to extract that "e"!
>
> I had thought that
> h[!duplicated(h)]
> might work but it simply returns all the unique values
> whereas
> I simply want to simply find the odd man out.
>
> I thought of using sorting the vectors & using a cbind
> but the id's are assigned
> more or less randomly so that didn't work.
>
> Thanks
>
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>

Charles C. Berry                        (858) 534-2098
                                          Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	         UC San Diego
http://biostat.ucsd.edu/~cberry/         La Jolla, San Diego 92093-0901