Modifying timezone of a POSIXct object without changing the display

Question

I have a POSIXct object and would like to change it\'s tz attribute WITHOUT R to interpret it (interpret it would mean to change how the datetime is di

Answer 1

An alternative to the lubridate package is via conversion to and back from character type:

recastTimezone.POSIXct <- function(x, tz) return(
  as.POSIXct(as.character(x), origin = as.POSIXct("1970-01-01"), tz = tz))

(Adapted from GSee's answer)

Don't know if this is efficient, but it would work for time zones with daylight savings.

Test code:

x <- as.POSIXct('2003-01-03 14:00:00', tz = 'Etc/UTC')
x
recastTimezone.POSIXct(x, tz = 'Australia/Melbourne')

Output:

[1] "2003-01-03 14:00:00 UTC"
[1] "2003-01-03 14:00:00 AEDT" # Nothing is changed apart from the time zone.

Output if I replaced as.character() by as.numeric() (as GSee had done):

[1] "2003-01-03 14:00:00 UTC"
[1] "2003-01-03 15:00:00 AEDT" # An hour is added.