Hello,
I have a question regarding the date objects and timezones. My current
understanding is, that a Date object does only save the days from the
origin and no more information about timezones or other information
(please correct me if I am wrong).
But if I use
d = as.Date("2024-11-11")
or
d = as.Date("2024-11-11", tz="America/New_York")
the date object is displayed in my RStudio environment as "2024-11-11
UTC". If I try to read the timezone information from the date object in
the ways possible for POSIX, I will get NULL as return:
> attr(d, "tzone")
NULL
Also unclassing the object does not reveal any information about the
timezone, unlike for POSIX objects
> unclass(d)
[1] 20038
In contrast, getting the timezone information with base::format will
yield the timezone information
> base::format(d, format="%Z")
[1] "UTC"
As for my current understanding, setting the tz Argument in as.Date will
only have an effect if the input is a date-time such as POSIX and else
it has no effect and it is not possible to set a timezone for an Date
object. But is this the case if there is some timezone information
present when using base::format or in the display in the RStudio
environment? Is there any way to add timezone information to an Date
object (other than UTC) and keeping it a Date object? And if not how is
the Date object internally structured, so that it will return "UTC" when
using base::format or in the RStudio environment? Is this due to some
default behavior of R?
Best regards,
Luca
My Session Info:
R version 4.3.2 (2023-10-31 ucrt)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 11 x64 (build 22631)
Matrix products: default
locale:
[1] LC_COLLATE=German_Germany.utf8 LC_CTYPE=German_Germany.utf8
LC_MONETARY=German_Germany.utf8
[4] LC_NUMERIC=C LC_TIME=German_Germany.utf8
time zone: Europe/Berlin
tzcode source: internal
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