[Rd] 'vapply' not returning list element names when returned element is a length-1 list

Dean Attali daattali at gmail.com
Thu Aug 6 04:35:44 CEST 2015

Thank you, I do see that now. I still don't completely agree with the
behaviour, I hoped there would be a way to not simplify, but thank you for
pointing me to the fact that it is documented.


On 5 August 2015 at 05:08, S Ellison <S.Ellison at lgcgroup.com> wrote:

> > -----Original Message-----
> > From: R-devel [mailto:r-devel-bounces at r-project.org] On Behalf Of Dean
> Attali
> > If i have a function that returns a named list with 2 (or more) elements,
> > then using 'vapply' retains the names of the elements:
> > ....
> > But if the function only returns one element, then the name "foo" is lost
> vapply _always simplifies_ according to the documentation.
> In the first case (function return value contains more than one element,
> and each ), vapply simplifies to a matrix of two lists (!).  The names
> "foo" and "hello" have been added to the dimnames so you can tell which is
> which.
> in the second case the function return value is a single list and not a
> matrix of lists (a simple list is simpler than a matrix of lists). The name
> of the list ('foo') has nowhere to go; instead, you would be assigning the
> list to a named variable and you don't need the name 'foo'.
> Whether that is inconsistent is something of a matter of perspective.
> Simplification applied as far as possible will always depend on what
> simplification is possible for the particular return values, so different
> return values provide different behaviour.
> S Ellison
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