as.Date without "origin"

Dear all,

I would throw in my vote to have origin = "1970-01-01" as a default in as.Date().  Why?  Well, in fact, the "converse" function as.numeric() does have an implicit default:
as.numeric(Sys.Date())
[1] 19298

In fact, as.numeric seems to not even have a method for class "Date", and so as.numeric() does not even have an argument "origin" or the like.

In any case, when using Date objects, it may happen that the result is of clas numeric. For example:
ifelse(TRUE, Sys.Date(), Sys.Date() + 1)
[1] 19298

So, in order to transform the result back to class "Date" using as.Date(), I always need to remember the universal default origin 1970-01-01 and I need to write it out explicitly.

I find that rather inconvenient, and so having the default origin as a default would make very much sense to me here.

Of course, for that particular example, it would also help me if ifelse() would properly handle Date vectors.

Best
Johannes
Gesendet: Mittwoch, 02. November 2022 um 14:38 Uhr
Von: "Dan Dalthorp via R-devel" <r-devel at r-project.org>
An: "Spencer Graves" <spencer.graves at prodsyse.com>
Cc: "r-devel at r-project.org" <r-devel at r-project.org>
Betreff: Re: [Rd] as.Date without "origin"

I don't see a compelling rationale for changing the default behavior as.Date to deviate from the wholly reasonable status quo of "as.Date will accept numeric data (the number of days since an epoch), but only if origin is supplied." That has been the expectation for a long, long time.

In any case, the manual should match the behavior.

-DHD

------- Original Message -------
On Wednesday, November 2nd, 2022 at 6:20 AM, Spencer Graves <spencer.graves at prodsyse.com> wrote:

I've felt that "as.Date" should default to origin "1970-01-01", so I
added a modification to Ecfun:

Ecfun::as.Date1970(0)

If R-devel chose to change the default on this, I would happily
deprecate Ecfun::as.Date1970 in favor of base::as.Date ;-)

I would therefore support changing the documentation to match the new
behavior.

Spencer Graves

On 11/2/22 7:30 AM, Dan Dalthorp via R-devel wrote:

The new (2022-10-11 r83083 ucrt) as.Date function returns a date rather than an error when called without "origin" specified.

# previous versions of R
as.Date(0)
# Error in as.Date.numeric(0) : 'origin' must be supplied

# new:
as.Date(0)
# [1] "1970-01-01"

This is at odds with the help file, which gives:

origin

aDateobject, or something which can be coerced byas.Date(origin, ...)to such an object.

And:
as.Datewill accept numeric data (the number of days since an epoch), butonlyiforiginis supplied.

The behavior described in the help file and implemented in previous versions seems more reasonable than returning a date with an arbitrary "origin". In any case, in the r-devel there is a mismatch between the function and its description.

-Dan
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as.Date without "origin"

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