[Rd] head/tail breaking change

[Jan Gorecki]

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