[Rd] all.equal.list() sometimes fails with unnamed and named
Prof Brian D Ripley
Wed, 4 Oct 2000 07:27:02 +0100 (BST)
On Wed, 4 Oct 2000, Kurt Hornik wrote:
> > I think that both the names and components should match exactly (the
> > components recursively). Unfortunately the named-component extraction
> > is partial matching (at least, sometimes) so the ordering of the names
> > always matters. (There's an S/R difference here I keep forgetting to
> > write down. I think it is
> > x <- list(aa=1, bb=2)
> > x["a"]
> > which gives in S
> > $aa:
> >  1
> > and in R
> > $"NA"
> > NULL
> > so S always partial matches, but R does not always.)
> More precisely, we have
> R> x[["a"]]
>  1
> R> x["a"]
> Does this make sense at all? Comparing it to
> R> x <- list(aa=1, bb=2, "NA"=3)
> R> x["NA"]
>  3
> I would think that the x["a"] incorrectly indicates that the list has a
> named component "NA" with value NULL ...
Yes, so would I. I think it is a bug in R.
> What should we do about all.equal.list()? Should we deal with the named
> components first and strip them off, or always go the positional route?
> Your comment that lists are generic vectors would indicate that the
> second approach is more appropriate ...
See the first two lines I've left here. I think it should be positional
matching *and* the names should match too. That is, all.equal.list would
fail if one list had names and other did not.
Brian D. Ripley, firstname.lastname@example.org
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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