[Rd] head/tail breaking change

[Gabriel Becker]

Jan,

That is an intentional change as you can see in the documentation for
head/tail in R-devel. Last time I discussed it with Martin, this behavior
was desired and thus is unlikely to change unless "our" (ie his) mind does.

The hope is that the new behavior is actually what people would want (note
it already behaves this way for data.frames and for matrices, which are now
explicitly array objects with 2 dimensions as well as classed as matrices,
so its more consistent now, and more reasonable for the object).

Best,
~G

On Wed, Dec 18, 2019 at 2:44 AM Jan Gorecki <j.gorecki using wit.edu.pl> wrote:

> Hi R-devel community,
>
> I am aware of changes in R-devel in head/tail methods but I was not
> expecting that to be a breaking change.
>
> # R 3.6.1
> ar = array(1:27, c(3,3,3))
> tail(ar, 1)
> #[1] 27
>
> The current output of R-devel is something that I would expect from a
>
> tail(ar, c(1, Inf, Inf))
>
> or
>
> tail(ar, c(1, NA, NA))
>
> calls.
> Is it going to stay like this or there are plans to mitigate this
> breaking change?
>
> # R-devel 2019-12-17 r77592
> ar = array(1:27, c(3,3,3))
> tail(ar, 1)
> #, , 1
> #
> #     [,1] [,2] [,3]
> #[3,]    3    6    9
> #
> #, , 2
> #
> #     [,1] [,2] [,3]
> #[3,]   12   15   18
> #
> #, , 3
> #
> #     [,1] [,2] [,3]
> #[3,]   21   24   27
>
> Best,
> Jan Gorecki
>
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