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force_tz returns the date-time that has the same clock time as input time, but in the new time zone. force_tzs is the parallel version of force_tz, meaning that every element from time argument is matched with the corresponding time zone in tzones argument.


force_tz(time, tzone = "", roll = FALSE)

force_tzs(time, tzones, tzone_out = "UTC", roll = FALSE)



a POSIXct, POSIXlt, Date, chron date-time object, or a data.frame object. When a data.frame all POSIXt elements of a data.frame are processed with force_tz() and new data.frame is returned.


a character string containing the time zone to convert to. R must recognize the name contained in the string as a time zone on your system.


logical. If TRUE, and time falls into the DST-break, assume the next valid civil time, otherwise return NA. See examples.


character vector of timezones to be "enforced" on time time stamps. If time and tzones lengths differ, the smaller one is recycled in accordance with usual R conventions.


timezone of the returned date-time vector (for force_tzs).


a POSIXct object in the updated time zone


Although the new date-time has the same clock time (e.g. the same values in the year, month, days, etc. elements) it is a different moment of time than the input date-time.

As R date-time vectors cannot hold elements with non-uniform time zones, force_tzs returns a vector with time zone tzone_out, UTC by default.


x <- ymd_hms("2009-08-07 00:00:01", tz = "America/New_York")
force_tz(x, "UTC")
#> [1] "2009-08-07 00:00:01 UTC"
force_tz(x, "Europe/Amsterdam")
#> [1] "2009-08-07 00:00:01 CEST"

## DST skip:

y <- ymd_hms("2010-03-14 02:05:05 UTC")
force_tz(y, "America/New_York", roll=FALSE)
#> [1] NA
force_tz(y, "America/New_York", roll=TRUE)
#> [1] "2010-03-14 03:00:00 EDT"

## Heterogeneous time-zones:

x <- ymd_hms(c("2009-08-07 00:00:01", "2009-08-07 01:02:03"))
force_tzs(x, tzones = c("America/New_York", "Europe/Amsterdam"))
#> [1] "2009-08-07 04:00:01 UTC" "2009-08-06 23:02:03 UTC"
force_tzs(x, tzones = c("America/New_York", "Europe/Amsterdam"), tzone_out = "America/New_York")
#> [1] "2009-08-07 00:00:01 EDT" "2009-08-06 19:02:03 EDT"

x <- ymd_hms("2009-08-07 00:00:01")
force_tzs(x, tzones = c("America/New_York", "Europe/Amsterdam"))
#> [1] "2009-08-07 04:00:01 UTC" "2009-08-06 22:00:01 UTC"