Change the time zone of a sub-daily zoo object

Changes the time zone used by the time index of a sub-daily zoo object whose index inherits from POSIXct or POSIXlt.

Usage

change_tz(x, ...)

# S3 method for class 'zoo'
change_tz(x, new.tz, old.tz=NULL, ...)

Arguments

x: zoo object with a sub-daily POSIXct or POSIXlt time index.
new.tz: character. Time zone to assign to the output time index.
old.tz: character or NULL. Time zone currently used by the time index. When NULL, it is inferred from attr(time(x), "tzone"). When provided, it must match the detected time zone when the time index already has one.
...: further arguments passed to or from other methods.

Details

Both old.tz and new.tz are checked against OlsonNames.

change_tz() preserves the represented instants and changes their time zone for display and downstream calendar grouping. For example, midnight UTC is shown as the previous evening in "America/Santiago" when the applicable UTC offset is negative. It does not reinterpret clock labels in a new time zone.

The values and dimensions of x are preserved; only the time index is changed.

Value

A zoo object with the same values as x, but with its time index converted to new.tz.

Author

Mauricio Zambrano-Bigiarini, mzb.devel@gmail.com

Examples

dates <- seq(as.POSIXct("2001-01-01 00:00:00", tz="UTC"),
             by="hour", length.out=3)
x <- zoo(1:3, dates)

y <- change_tz(x, new.tz="America/Santiago")
time(y)
#> [1] "2000-12-31 21:00:00 -03" "2000-12-31 22:00:00 -03"
#> [3] "2000-12-31 23:00:00 -03"

## The represented instants and the observed values are preserved.
identical(as.numeric(time(x)), as.numeric(time(y)))
#> [1] TRUE
identical(coredata(x), coredata(y))
#> [1] TRUE