paleolimbot commented on code in PR #35671:
URL: https://github.com/apache/arrow/pull/35671#discussion_r1204045935
##########
r/R/dplyr-funcs-datetime.R:
##########
@@ -61,12 +61,14 @@ register_bindings_datetime_utility <- function() {
tz <- Sys.timezone()
}
- # if a timestamp does not contain timezone information (i.e. it is
+ # If a timestamp does not contain timezone information (i.e. it is
# "timezone-naive") we can attach timezone information (i.e. convert it
into
# a "timezone-aware" timestamp) with `assume_timezone`
# if we want to cast to a different timezone, we can only do it for
- # timezone-aware timestamps, not for timezone-naive ones
- if (!is.null(tz)) {
+ # timezone-aware timestamps, not for timezone-naive ones.
+ # strptime in Acero will return a timezone-aware timestamp if %z is
+ # part of the format string.
+ if (!is.null(tz) && !grepl("%z", format, fixed = TRUE)) {
Review Comment:
We don't have a naive datetime type in R...everything is timezone aware, and
`tz = ""` means "your local timezone" (but everything is UTC internally). What
you've encountered here is a fun type called the `POSIXlt` which is sort of
like a data frame that stores components in separate vectors (the `POSIXct` is
a more normal version of it, which is seconds from the unix epoch as a double
vector).
It's a good point that this doesn't match what base R does...I think we'd
want to `cast()` if `grepl("%z")` and `assume_timezone()` otherwise?
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
