[Rd] Allowing S3 methods of rounding functions to take `...`

[David Winsemius]

On 1/28/21 10:56 PM, Abby Spurdle wrote:
> I've been writing functions for block matrices and more generally,
> arrays of matrices.
>
> Presumably, the default transpose operation would transpose everything.
> But there are situations where one might want to transpose the
> top-level matrix (of submatrices) but not the submatrices, themselves.
> Or vice versa.


You could construct a matrix of lists and have the lists hold the 
sub-matrices.


-- 

David.

>
> On a side note, the help file for base::aperm is entitled "Array Transposition".
> So, this topic is not quite as simple as it may sound.
>
> Interestingly, the aperm generic function *does* have dots.
>
>
> On Fri, Jan 29, 2021 at 3:37 PM Gabriel Becker <gabembecker using gmail.com> wrote:
>> Out of my naive curiosity, what arguments are you hoping a method for t() will take?
>>
>> I mean honestly an argument could be made that all S3 generics should take .... I don't think its an overwhelmingly compelling one, but I d see some merit to it given what an s3 generic is at its core.
>>
>> ~G
>>
>> On Thu, Jan 28, 2021 at 5:27 PM Abby Spurdle <spurdle.a using gmail.com> wrote:
>>> That's a great suggestion Davis.
>>>
>>> While, we're on the topic...
>>> Could we have a "dots" argument in base::t, the transpose function?
>>>
>>>
>>> On Fri, Jan 29, 2021 at 4:48 AM Davis Vaughan <davis using rstudio.com> wrote:
>>>> I should also say that I would be willing to attempt a patch for this, if
>>>> others agree that this would be useful.
>>>>
>>>> - Davis
>>>>
>>>> On Thu, Jan 28, 2021 at 9:14 AM Davis Vaughan <davis using rstudio.com> wrote:
>>>>
>>>>> Hi all,
>>>>>
>>>>> I would like to propose adding `...` to the signatures of the following
>>>>> rounding functions:
>>>>>
>>>>> - floor(x)
>>>>> - ceiling(x)
>>>>> - round(x, digits = 0)
>>>>> - And possibly signif(x, digits = 6)
>>>>>
>>>>> The purpose would be to allow S3 methods to add additional arguments as
>>>>> required.
>>>>>
>>>>> A few arguments in favor of this change:
>>>>>
>>>>> `trunc(x, ...)` already takes dots, which sets a precedent for the others
>>>>> to do so as well. It is documented in the same help file as the other
>>>>> rounding functions.
>>>>>
>>>>> Internally at the C level, a check is done to ensure that there is exactly
>>>>> 1 arg for floor() and ceiling(), and either 1 or 2 args for round(). The
>>>>> actual names of those arguments are not checked, however, and I believe
>>>>> this is what allows `round.Date(x, ...)` and `round.POSIXt(x, unit)` to
>>>>> exist, solely because they have 2 arguments. It seems like this is a bit of
>>>>> a hack, since you couldn't create something similar for floor, like
>>>>> `floor.POSIXt(x, unit)` (not saying this should exist, it is just for
>>>>> argument's sake), because the 1 argument check would error on this. I think
>>>>> adding `...` to the signature of the generics would better support what is
>>>>> being done here.
>>>>>
>>>>> Additionally, I have a custom date-like S3 class of my own that I would
>>>>> like to write floor(), ceiling(), and round() methods for, and they would
>>>>> require passing additional arguments.
>>>>>
>>>>> If R core would like to make this change, they could probably tweak
>>>>> `do_trunc()` to be a bit more general, and use it for floor() and
>>>>> ceiling(), since it already allows `...`.
>>>>>
>>>>> A few references:
>>>>>
>>>>> Check for 1 arg in do_math1(), used by floor() and ceiling()
>>>>>
>>>>> https://github.com/wch/r-source/blob/fe82da3baf849fcd3cc7dbc31c6abc72b57aa083/src/main/arithmetic.c#L1270
>>>>>
>>>>> Check for 2 args in do_Math2(), used by round()
>>>>>
>>>>> https://github.com/wch/r-source/blob/fe82da3baf849fcd3cc7dbc31c6abc72b57aa083/src/main/arithmetic.c#L1655
>>>>>
>>>>> do_trunc() definition that allows `...`
>>>>>
>>>>> https://github.com/wch/r-source/blob/fe82da3baf849fcd3cc7dbc31c6abc72b57aa083/src/main/arithmetic.c#L1329-L1340
>>>>>
>>>>> - Davis
>>>>>
>>>>          [[alternative HTML version deleted]]
>>>>
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