tzone: Get or Replace the Timezone of an xts Object's Index

In joshuaulrich/xts: eXtensible Time Series

Get or Replace the Timezone of an xts Object's Index

Description

Generic functions to get or replace the timezone of an xts object's index.

Usage

tzone(x, ...)
tzone(x) <- value

## S3 method for class 'xts'
tzone(x, ...)
## S3 replacement method for class 'xts'
tzone(x) <- value

##### The functions below are DEPRECATED #####
indexTZ(x, ...)
indexTZ(x) <- value

Arguments

x	an xts object
value	a valid timezone value (see OlsonNames())
...	arguments passed to other methods

Details

Internally, an xts object's index is a numeric value corresponding to seconds since the epoch in the UTC timezone. When an xts object is created, all time index values are converted internally to POSIXct (which is also in seconds since the UNIX epoch), using the underlying OS conventions and the TZ environment variable. The xts() function manages timezone information as transparently as possible.

The tzone<- function does not change the internal index values (i.e. the index will remain the same time in the UTC timezone).

Value

A one element named vector containing the timezone of the object's index.

Note

Both indexTZ and indexTZ<- are deprecated in favor of tzone and tzone<-, respectively.

Problems may arise when an object that had been created under one timezone are used in a session using another timezone. This isn't usually a issue, but when it is a warning is given upon printing or subsetting. This warning may be suppressed by setting options(xts_check_TZ = FALSE).

Note

Both indexTZ and indexTZ<- are deprecated in favor of tzone and tzone<-, respectively.

Timezones are a difficult issue to manage. It's best to set the system TZ environment variable to "GMT" or "UTC" (via Sys.setenv(TZ = "UTC") at the beginning of your scripts if you do not need intra-daily resolution.

Author(s)

Jeffrey A. Ryan

See Also

POSIXt index has more information on the xts index, tformat describes how the index values are formatted when printed, and tclass provides details how xts handles the class of the index.

Examples

# Date indexes always have a "UTC" timezone
x <- xts(1, Sys.Date())
tzone(x)
str(x)
print(x)

# The default 'tzone' is blank -- your machine's local timezone,
# determined by the 'TZ' environment variable.
x <- xts(1, Sys.time())
tzone(x)
str(x)

# now set 'tzone' to different values
tzone(x) <- "UTC"
str(x)

tzone(x) <- "America/Chicago"
str(x)

y <- timeBasedSeq('2010-01-01/2010-01-03 12:00/H')
y <- xts(seq_along(y), y, tzone = "America/New_York")

# Changing the tzone does not change the internal index values, but it
# does change how the index is printed!
head(y)
head(.index(y))
tzone(y) <- "Europe/London"
head(y)          # the index prints with hours, but
head(.index(y))  # the internal index is not changed!

joshuaulrich/xts documentation built on March 9, 2024, 2:50 a.m.