[Rd] Ordering of values returned by unique

Earl F. Glynn efg at stowers-institute.org
Wed Sep 29 18:39:52 CEST 2004

"Tony Plate" <tplate at blackmesacapital.com> wrote in message
news: at mailhost.blackmesacapital.com...
> I depend on this all the time, so I also checked some references.  In the
> Blue book the documentation for the functions unique and duplicated is
> combined and implies the above.  In MASS 4th Ed, the page referred to by
> the index entry for 'unique' (p48, #9 in my copy) states that 'unique'
> removes duplicates as identified by 'duplicated', which implies that the
> order of retained elements is not changed.  The Green book has no index
> entry for 'unique'.  In S-plus the implementation of unique.default(x)
> x[!duplicated(x)].

So what is the "Blue book", the "Green book", and MASS 4th Ed?


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