[R] vector problems
Prof Brian Ripley
ripley at stats.ox.ac.uk
Mon Nov 5 16:22:07 CET 2001
On 5 Nov 2001, Christopher Fonnesbeck wrote:
> I dont get it:
> > is.vector(c(mydf))
>  TRUE
> > unique(c(mydf))
> Error in unique(c(mydf)) : unique() applies only to vectors
> Is it a vector or not? This stuff is driving me nuts. I'm simply trying
> to convince R that my grouping vector is actually a vector so that
> unique will work. Its just a vector of numbers, so why shouldnt it work?
Well, how about giving us some reasonable amount of information and an
example we can check over for you?
A reasonable guess is that mydf is a data frame. In that case mydf is a
list, which is a vector, but not an atomic vector and so unique() does not
apply. I don't know what you think c() does: it is strips attributes of
atomic vectors, but also works for lists, in a different way.
My guess is that you intended mydf[].
> mydf <- data.frame(x=1:10, y=1:10)
Error in unique(c(mydf)) : unique() applies only to vectors
 1 2 3 4 5 6 7 8 9 10
would seem to match the scanty evidence given.
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272860 (secr)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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