[R] Finding a single unique item in duplicated vectors

[John Kane]

Arrgh! I knew it going to be was blindingly obvious
once someone showed it to me.  I had even looked at
diff() at one point but never found setdiff.  ?sets
did not seem to find anything. 

Thanks very much.

--- "Charles C. Berry" <cberry at tajo.ucsd.edu> wrote:

> 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
> >
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained,
> reproducible code.
> >
> 
> 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
> 
> 
>