R: Query or Set Aspects of the Locale

locales {base} | R Documentation

## Query or Set Aspects of the Locale

### Description

Get details of or set aspects of the locale for the R process.

### Usage

    Sys.getlocale(category = "LC_ALL")
    Sys.setlocale(category = "LC_ALL", locale = "")

### Arguments

`category` | character string. The following categories should always be supported: `"LC_ALL"`, `"LC_COLLATE"`, `"LC_CTYPE"`, `"LC_MONETARY"`, `"LC_NUMERIC"` and `"LC_TIME"`. Some systems (not Windows) will also support `"LC_MESSAGES"`, `"LC_PAPER"` and `"LC_MEASUREMENT"`.
`locale` | character string. A valid locale name on the system in use. Normally `""` (the default) will pick up the default locale for the system.

### Details

The locale describes aspects of the internationalization of a program. Initially most aspects of the locale of R are set to `"C"` (which is the default for the C language and reflects North-American usage). R sets `"LC_CTYPE"` and `"LC_COLLATE"`, which allow the use of a different character set and alphabetic comparisons in that character set (including the use of `sort`), `"LC_MONETARY"` (for use by `Sys.localeconv`) and `"LC_TIME"` may affect the behaviour of `as.POSIXlt` and `strptime` and functions which use them (but not `date`).

The first seven categories described here are those specified by POSIX. `"LC_MESSAGES"` will be `"C"` on systems that do not support message translation, and is not supported on Windows. Trying to use an unsupported category is an error for `Sys.setlocale`.

Note that setting category `"LC_ALL"` sets only `"LC_COLLATE"`, `"LC_CTYPE"`, `"LC_MONETARY"` and `"LC_TIME"`.

Attempts to set an invalid locale are ignored. There may or may not be a warning, depending on the OS.

Attempts to change the character set (by `Sys.setlocale("LC_TYPE", )`, if that implies a different character set) during a session may not work and are likely to lead to some confusion.

Note that the LANGUAGE environment variable has precedence over `"LC_MESSAGES"` in selecting the language for message translation on most R platforms.

On platforms where ICU is used for collation the locale used for collation can be reset by `icuSetCollate`). Except on Windows, the initial setting is taken from the `"LC_COLLATE"` category, and it is reset when this is changed by a call to `Sys.setlocale`.

### Value

A character string of length one describing the locale in use (after setting for `Sys.setlocale`), or an empty character string if the current locale settings are invalid or `NULL` if locale information is unavailable.

For `category = "LC_ALL"` the details of the string are system-specific: it might be a single locale name or a set of locale names separated by `"/"` (Solaris, OS X) or `";"` (Windows, Linux). For portability, it is best to query categories individually: it is not necessarily the case that the result of `foo <- Sys.getlocale()` can be used in `Sys.setlocale("LC_ALL", locale = foo)`.

### Warning

Setting `"LC_NUMERIC"` may cause R to function anomalously, so gives a warning. Input conversions in R itself are unaffected, but the reading and writing of ASCII `save` files will be, as may packages.

Setting it temporarily on a Unix-alike to produce graphical or text output may work well enough, but `options(OutDec)` is often preferable.

Almost all the output routines used by R itself under Windows ignore the setting of `"LC_NUMERIC"` since they make use of the Trio library which is not internationalized.

### Note

Changing the values of locale categories whilst R is running ought to be noticed by the OS services, and usually is but exceptions have been seen (usually in collation services).

### See Also

`strptime` for uses of `category = "LC_TIME"`. `Sys.localeconv` for details of numerical and monetary representations.

`l10n_info` gives some summary facts about the locale and its encoding.

The ‘R Installation and Administration’ manual for background on locales and how to find out locale names on your system.

### Examples

    Sys.getlocale()
    Sys.getlocale("LC_TIME")
    ## Not run:
    Sys.setlocale("LC_TIME", "de")     # Solaris: details are OS-dependent
    Sys.setlocale("LC_TIME", "de_DE.utf8")   # Modern Linux etc.
    Sys.setlocale("LC_TIME", "de_DE.UTF-8")  # ditto
    Sys.setlocale("LC_TIME", "de_DE")  # OS X, in UTF-8
    Sys.setlocale("LC_TIME", "German") # Windows

    ## End(Not run)
    Sys.getlocale("LC_PAPER")          # may or may not be set

    ## Not run:
    Sys.setlocale("LC_COLLATE", "C")   # turn off locale-specific sorting,
                                       # usually, but not on all platforms
    ## End(Not run)

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