R devel - Feb 2024 - round.Date and trunc.Date not working / implemented

>>>>> Ji?? Moravec 
>>>>>     on Wed, 7 Feb 2024 10:23:15 +1300 writes:
    > This is my first time working with dates, so if the answer is
"Duh, work
    > with POSIXt", please ignore it.

    > Why is not `round.Date` and `trunc.Date` "implemented" for
`Date`?

    > Is this because `Date` is (mostly) a virtual class setup for a better 
    > inheritance or is that something that is just missing? (like 
    > `sort.data.frame`). Would R core welcome a patch?

    > I decided to convert some dates to date using `as.Date` function, which
    > converts to a plain `Date` class, because that felt natural.

    > But then when trying to round to closest year, I have realized that the
    > `round` and `trunc` for `Date` do not behave as for `POSIXt`.

    > I would assume that these will have equivalent output:

    > Sys.time() |> round("years") # 2024-01-01 NZDT

    > Sys.Date() |> round("years") # Error in
round.default(...): non-numeric
    > argument to mathematical function


    > Looking at the code (and reading the documentation more carefully)
shows
    > the issue, but this looks like an omission that should be patched.

    > -- Jirka

You are wrong:  They *are* implemented,
both even visible since they are in the 'base' package!

==> they have help pages you can read ....

Here are examples:
> trunc(Sys.Date())
[1] "2024-02-08"
> trunc(Sys.Date(), "month")
[1] "2024-02-01"
> trunc(Sys.Date(), "year")
[1] "2024-01-01"
>

> On 8 Feb 2024, at 15:15, Martin Maechler <maechler at
stat.math.ethz.ch> wrote:
> 
>>>>>> Ji?? Moravec 
>>>>>>    on Wed, 7 Feb 2024 10:23:15 +1300 writes:
> 
>> This is my first time working with dates, so if the answer is
"Duh, work
>> with POSIXt", please ignore it.
> 
>> Why is not `round.Date` and `trunc.Date` "implemented" for
`Date`?
> 
>> Is this because `Date` is (mostly) a virtual class setup for a better 
>> inheritance or is that something that is just missing? (like 
>> `sort.data.frame`). Would R core welcome a patch?
> 
>> I decided to convert some dates to date using `as.Date` function, which
>> converts to a plain `Date` class, because that felt natural.
> 
>> But then when trying to round to closest year, I have realized that the
>> `round` and `trunc` for `Date` do not behave as for `POSIXt`.
> 
>> I would assume that these will have equivalent output:
> 
>> Sys.time() |> round("years") # 2024-01-01 NZDT
> 
>> Sys.Date() |> round("years") # Error in
round.default(...): non-numeric
>> argument to mathematical function
> 
> 
>> Looking at the code (and reading the documentation more carefully)
shows
>> the issue, but this looks like an omission that should be patched.
> 
>> -- Jirka
> 
> You are wrong:  They *are* implemented,
> both even visible since they are in the 'base' package!
> 
> ==> they have help pages you can read ....
> 
> Here are examples:
> 
>> trunc(Sys.Date())
> [1] "2024-02-08"
>> trunc(Sys.Date(), "month")
> [1] "2024-02-01"
>> trunc(Sys.Date(), "year")
> [1] "2024-01-01"
>> 
> 
Maybe he meant

r$> Sys.time() |> round.POSIXt("years")
[1] "2024-01-01 CET"

r$> Sys.Date() |> round.POSIXt("years")
[1] "2024-01-01 UTC"

The only difference is the timezone
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

Apologies then. I was using R version 4.1.2 (Bird Hippie) and looks like 
someone implemented a better trunc.Date version in the meantime.

# v4.1.2
 > trunc.Date
function (x, ...)
round(x - 0.4999999)
<bytecode: 0x56138c284de0>
<environment: namespace:base>

# Unstable (2024-02-07 r85873)
 > trunc.Date
function (x, units = c("secs", "mins", "hours",
"days", "months",
 ??? "years"), ...)
{
 ??? units <- match.arg(units)
 ??? if (units == "months" || units == "years")
 ??????? as.Date(trunc.POSIXt(x, units, ...))
 ??? else round(x - 0.4999999)
}
<bytecode: 0x565254ea8398>
<environment: namespace:base>


And I was looking towards my first contribution. :(
Well, its on me for not checking the dev version before writing email 
and using something that is 3 years out of date.

Look like the change did not affected `round.Date`. In both versions it 
is still not accepting `units` and instead treating `Date(...)` as numeric.

Would similar treatment for `round.Date` be desirable? And perhaps 
`floor` and `ceiling` (rounding up)? I found it useful when plotting 
(although axis.Date and prettyDate did solved some issues). Although

-- Jirka


On 9/02/24 03:15, Martin Maechler wrote:
>>>>>> Ji?? Moravec
>>>>>>      on Wed, 7 Feb 2024 10:23:15 +1300 writes:
>      > This is my first time working with dates, so if the answer is
"Duh, work
>      > with POSIXt", please ignore it.
>
>      > Why is not `round.Date` and `trunc.Date` "implemented"
for `Date`?
>
>      > Is this because `Date` is (mostly) a virtual class setup for a
better
>      > inheritance or is that something that is just missing? (like
>      > `sort.data.frame`). Would R core welcome a patch?
>
>      > I decided to convert some dates to date using `as.Date` function,
which
>      > converts to a plain `Date` class, because that felt natural.
>
>      > But then when trying to round to closest year, I have realized
that the
>      > `round` and `trunc` for `Date` do not behave as for `POSIXt`.
>
>      > I would assume that these will have equivalent output:
>
>      > Sys.time() |> round("years") # 2024-01-01 NZDT
>
>      > Sys.Date() |> round("years") # Error in
round.default(...): non-numeric
>      > argument to mathematical function
>
>
>      > Looking at the code (and reading the documentation more
carefully) shows
>      > the issue, but this looks like an omission that should be
patched.
>
>      > -- Jirka
>
> You are wrong:  They *are* implemented,
> both even visible since they are in the 'base' package!
>
> ==> they have help pages you can read ....
>
> Here are examples:
>
>> trunc(Sys.Date())
> [1] "2024-02-08"
>> trunc(Sys.Date(), "month")
> [1] "2024-02-01"
>> trunc(Sys.Date(), "year")
> [1] "2024-01-01"