locale— Internationalization services

Source code:Lib/locale.py

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Thelocalemodule opens access to the POSIX locale database and functionality. The POSIX locale mechanism allows programmers to deal with certain cultural issues in an application, without requiring the programmer to know all the specifics of each country where the software is executed.

Thelocalemodule is implemented on top of the_localemodule, which in turn uses an ANSI C locale implementation if available.

Thelocalemodule defines the following exception and functions:

exceptionlocale.Error

Exception raised when the locale passed tosetlocale()is not recognized.

locale.setlocale(category,locale=None)

Iflocaleis given and notNone,setlocale()modifies the locale setting for thecategory.The available categories are listed in the data description below.localemay be a string, or an iterable of two strings (language code and encoding). If it’s an iterable, it’s converted to a locale name using the locale aliasing engine. An empty string specifies the user’s default settings. If the modification of the locale fails, the exception Erroris raised. If successful, the new locale setting is returned.

Iflocaleis omitted orNone,the current setting forcategoryis returned.

setlocale()is not thread-safe on most systems. Applications typically start with a call of

importlocale
locale.setlocale(locale.LC_ALL,'')

This sets the locale for all categories to the user’s default setting (typically specified in theLANGenvironment variable). If the locale is not changed thereafter, using multithreading should not cause problems.

locale.localeconv()

Returns the database of the local conventions as a dictionary. This dictionary has the following strings as keys:

Category	Key	Meaning
LC_NUMERIC	'decimal_point'	Decimal point character.
	'grouping'	Sequence of numbers specifying which relative positions the 'thousands_sep'is expected. If the sequence is terminated with CHAR_MAX,no further grouping is performed. If the sequence terminates with a 0,the last group size is repeatedly used.
	'thousands_sep'	Character used between groups.
LC_MONETARY	'int_curr_symbol'	International currency symbol.
	'currency_symbol'	Local currency symbol.
	'p_cs_precedes/n_cs_precedes'	Whether the currency symbol precedes the value (for positive resp. negative values).
	'p_sep_by_space/n_sep_by_space'	Whether the currency symbol is separated from the value by a space (for positive resp. negative values).
	'mon_decimal_point'	Decimal point used for monetary values.
	'frac_digits'	Number of fractional digits used in local formatting of monetary values.
	'int_frac_digits'	Number of fractional digits used in international formatting of monetary values.
	'mon_thousands_sep'	Group separator used for monetary values.
	'mon_grouping'	Equivalent to'grouping', used for monetary values.
	'positive_sign'	Symbol used to annotate a positive monetary value.
	'negative_sign'	Symbol used to annotate a negative monetary value.
	'p_sign_posn/n_sign_posn'	The position of the sign (for positive resp. negative values), see below.

All numeric values can be set toCHAR_MAXto indicate that there is no value specified in this locale.

The possible values for'p_sign_posn'and'n_sign_posn'are given below.

Value	Explanation
0	Currency and value are surrounded by parentheses.
1	The sign should precede the value and currency symbol.
2	The sign should follow the value and currency symbol.
3	The sign should immediately precede the value.
4	The sign should immediately follow the value.
CHAR_MAX	Nothing is specified in this locale.

The function temporarily sets theLC_CTYPElocale to theLC_NUMERIC locale or theLC_MONETARYlocale if locales are different and numeric or monetary strings are non-ASCII. This temporary change affects other threads.

Changed in version 3.7:The function now temporarily sets theLC_CTYPElocale to the LC_NUMERIClocale in some cases.

locale.nl_langinfo(option)

Return some locale-specific information as a string. This function is not available on all systems, and the set of possible options might also vary across platforms. The possible argument values are numbers, for which symbolic constants are available in the locale module.

Thenl_langinfo()function accepts one of the following keys. Most descriptions are taken from the corresponding description in the GNU C library.

locale.CODESET

Get a string with the name of the character encoding used in the selected locale.

locale.D_T_FMT

Get a string that can be used as a format string fortime.strftime()to represent date and time in a locale-specific way.

locale.D_FMT

Get a string that can be used as a format string fortime.strftime()to represent a date in a locale-specific way.

locale.T_FMT

Get a string that can be used as a format string fortime.strftime()to represent a time in a locale-specific way.

locale.T_FMT_AMPM

Get a format string fortime.strftime()to represent time in the am/pm format.

locale.DAY_1

locale.DAY_2

locale.DAY_3

locale.DAY_4

locale.DAY_5

locale.DAY_6

locale.DAY_7

Get the name of the n-th day of the week.

Note

This follows the US convention ofDAY_1being Sunday, not the international convention (ISO 8601) that Monday is the first day of the week.

locale.ABDAY_1

locale.ABDAY_2

locale.ABDAY_3

locale.ABDAY_4

locale.ABDAY_5

locale.ABDAY_6

locale.ABDAY_7

Get the abbreviated name of the n-th day of the week.

locale.MON_1

locale.MON_2

locale.MON_3

locale.MON_4

locale.MON_5

locale.MON_6

locale.MON_7

locale.MON_8

locale.MON_9

locale.MON_10

locale.MON_11

locale.MON_12

Get the name of the n-th month.

locale.ABMON_1

locale.ABMON_2

locale.ABMON_3

locale.ABMON_4

locale.ABMON_5

locale.ABMON_6

locale.ABMON_7

locale.ABMON_8

locale.ABMON_9

locale.ABMON_10

locale.ABMON_11

locale.ABMON_12

Get the abbreviated name of the n-th month.

locale.RADIXCHAR

Get the radix character (decimal dot, decimal comma, etc.).

locale.THOUSEP

Get the separator character for thousands (groups of three digits).

locale.YESEXPR

Get a regular expression that can be used with the regex function to recognize a positive response to a yes/no question.

locale.NOEXPR

Get a regular expression that can be used with theregex(3)function to recognize a negative response to a yes/no question.

Note

The regular expressions forYESEXPRand NOEXPRuse syntax suitable for the regexfunction from the C library, which might differ from the syntax used inre.

locale.CRNCYSTR

Get the currency symbol, preceded by “-” if the symbol should appear before the value, “+” if the symbol should appear after the value, or “.” if the symbol should replace the radix character.

locale.ERA

Get a string that represents the era used in the current locale.

Most locales do not define this value. An example of a locale which does define this value is the Japanese one. In Japan, the traditional representation of dates includes the name of the era corresponding to the then-emperor’s reign.

Normally it should not be necessary to use this value directly. Specifying theEmodifier in their format strings causes thetime.strftime() function to use this information. The format of the returned string is not specified, and therefore you should not assume knowledge of it on different systems.

locale.ERA_D_T_FMT

Get a format string fortime.strftime()to represent date and time in a locale-specific era-based way.

locale.ERA_D_FMT

Get a format string fortime.strftime()to represent a date in a locale-specific era-based way.

locale.ERA_T_FMT

Get a format string fortime.strftime()to represent a time in a locale-specific era-based way.

locale.ALT_DIGITS

Get a representation of up to 100 values used to represent the values 0 to 99.

locale.getdefaultlocale([envvars])

Tries to determine the default locale settings and returns them as a tuple of the form(languagecode,encoding).

According to POSIX, a program which has not calledsetlocale(LC_ALL,'') runs using the portable'C'locale. Callingsetlocale(LC_ALL,'')lets it use the default locale as defined by theLANGvariable. Since we do not want to interfere with the current locale setting we thus emulate the behavior in the way described above.

To maintain compatibility with other platforms, not only theLANG variable is tested, but a list of variables given as envvars parameter. The first found to be defined will be used.envvarsdefaults to the search path used in GNU gettext; it must always contain the variable name 'LANG'.The GNU gettext search path contains'LC_ALL', 'LC_CTYPE','LANG'and'LANGUAGE',in that order.

Except for the code'C',the language code corresponds toRFC 1766. language codeandencodingmay beNoneif their values cannot be determined.

Deprecated since version 3.11, will be removed in version 3.15.

locale.getlocale(category=LC_CTYPE)

Returns the current setting for the given locale category as sequence containing language code,encoding.categorymay be one of theLC_*values exceptLC_ALL.It defaults toLC_CTYPE.

Except for the code'C',the language code corresponds toRFC 1766. language codeandencodingmay beNoneif their values cannot be determined.

locale.getpreferredencoding(do_setlocale=True)

Return thelocale encodingused for text data, according to user preferences. User preferences are expressed differently on different systems, and might not be available programmatically on some systems, so this function only returns a guess.

On some systems, it is necessary to invokesetlocale()to obtain the user preferences, so this function is not thread-safe. If invoking setlocale is not necessary or desired,do_setlocaleshould be set toFalse.

On Android or if thePython UTF-8 Modeis enabled, always return'utf-8',thelocale encodingand thedo_setlocale argument are ignored.

ThePython preinitializationconfigures the LC_CTYPE locale. See also thefilesystem encoding and error handler.

Changed in version 3.7:The function now always returns"utf-8"on Android or if the Python UTF-8 Modeis enabled.

locale.getencoding()

Get the currentlocale encoding:

• On Android and VxWorks, return"utf-8".

• On Unix, return the encoding of the currentLC_CTYPElocale. Return"utf-8"ifnl_langinfo(CODESET)returns an empty string: for example, if the current LC_CTYPE locale is not supported.

• On Windows, return the ANSI code page.

ThePython preinitializationconfigures the LC_CTYPE locale. See also thefilesystem encoding and error handler.

This function is similar to getpreferredencoding(False)except this function ignores thePython UTF-8 Mode.

Added in version 3.11.

locale.normalize(localename)

Returns a normalized locale code for the given locale name. The returned locale code is formatted for use withsetlocale().If normalization fails, the original name is returned unchanged.

If the given encoding is not known, the function defaults to the default encoding for the locale code just likesetlocale().

locale.resetlocale(category=LC_ALL)

Sets the locale forcategoryto the default setting.

The default setting is determined by callinggetdefaultlocale(). categorydefaults toLC_ALL.

Deprecated since version 3.11, will be removed in version 3.13.

locale.strcoll(string1,string2)

Compares two strings according to the currentLC_COLLATEsetting. As any other compare function, returns a negative, or a positive value, or0, depending on whetherstring1collates before or afterstring2or is equal to it.

locale.strxfrm(string)

Transforms a string to one that can be used in locale-aware comparisons. For example,strxfrm(s1)<strxfrm(s2)is equivalent tostrcoll(s1,s2)<0.This function can be used when the same string is compared repeatedly, e.g. when collating a sequence of strings.

locale.format_string(format,val,grouping=False,monetary=False)

Formats a numbervalaccording to the currentLC_NUMERICsetting. The format follows the conventions of the%operator. For floating-point values, the decimal point is modified if appropriate. IfgroupingisTrue, also takes the grouping into account.

Ifmonetaryis true, the conversion uses monetary thousands separator and grouping strings.

Processes formatting specifiers as informat%val,but takes the current locale settings into account.

Changed in version 3.7:Themonetarykeyword parameter was added.

locale.currency(val,symbol=True,grouping=False,international=False)

Formats a numbervalaccording to the currentLC_MONETARYsettings.

The returned string includes the currency symbol ifsymbolis true, which is the default. IfgroupingisTrue(which is not the default), grouping is done with the value. IfinternationalisTrue(which is not the default), the international currency symbol is used.

Note

This function will not work with the ‘C’ locale, so you have to set a locale viasetlocale()first.

locale.str(float)

Formats a floating-point number using the same format as the built-in function str(float),but takes the decimal point into account.

locale.delocalize(string)

Converts a string into a normalized number string, following the LC_NUMERICsettings.

Added in version 3.5.

locale.localize(string,grouping=False,monetary=False)

Converts a normalized number string into a formatted string following the LC_NUMERICsettings.

Added in version 3.10.

locale.atof(string,func=float)

Converts a string to a number, following theLC_NUMERICsettings, by callingfuncon the result of callingdelocalize()onstring.

locale.atoi(string)

Converts a string to an integer, following theLC_NUMERICconventions.

locale.LC_CTYPE

Locale category for the character type functions. Most importantly, this category defines the text encoding, i.e. how bytes are interpreted as Unicode codepoints. SeePEP 538andPEP 540for how this variable might be automatically coerced toC.UTF-8to avoid issues created by invalid settings in containers or incompatible settings passed over remote SSH connections.

Python doesn’t internally use locale-dependent character transformation functions fromctype.h.Instead, an internalpyctype.hprovides locale-independent equivalents likePy_TOLOWER.

locale.LC_COLLATE

Locale category for sorting strings. The functionsstrcoll()and strxfrm()of thelocalemodule are affected.

locale.LC_TIME

Locale category for the formatting of time. The functiontime.strftime() follows these conventions.

locale.LC_MONETARY

Locale category for formatting of monetary values. The available options are available from thelocaleconv()function.

locale.LC_MESSAGES

Locale category for message display. Python currently does not support application specific locale-aware messages. Messages displayed by the operating system, like those returned byos.strerror()might be affected by this category.

This value may not be available on operating systems not conforming to the POSIX standard, most notably Windows.

locale.LC_NUMERIC

Locale category for formatting numbers. The functionsformat_string(), atoi(),atof()andstr()of thelocalemodule are affected by that category. All other numeric formatting operations are not affected.

locale.LC_ALL

Combination of all locale settings. If this flag is used when the locale is changed, setting the locale for all categories is attempted. If that fails for any category, no category is changed at all. When the locale is retrieved using this flag, a string indicating the setting for all categories is returned. This string can be later used to restore the settings.

locale.CHAR_MAX

This is a symbolic constant used for different values returned by localeconv().

Example:

>>>importlocale
>>>loc=locale.getlocale()# get current locale
# use German locale; name might vary with platform
>>>locale.setlocale(locale.LC_ALL,'de_DE')
>>>locale.strcoll('f\xe4n','foo')# compare a string containing an umlaut
>>>locale.setlocale(locale.LC_ALL,'')# use user's preferred locale
>>>locale.setlocale(locale.LC_ALL,'C')# use default (C) locale
>>>locale.setlocale(locale.LC_ALL,loc)# restore saved locale

Background, details, hints, tips and caveats

The C standard defines the locale as a program-wide property that may be relatively expensive to change. On top of that, some implementations are broken in such a way that frequent locale changes may cause core dumps. This makes the locale somewhat painful to use correctly.

Initially, when a program is started, the locale is theClocale, no matter what the user’s preferred locale is. There is one exception: the LC_CTYPEcategory is changed at startup to set the current locale encoding to the user’s preferred locale encoding. The program must explicitly say that it wants the user’s preferred locale settings for other categories by callingsetlocale(LC_ALL,'').

It is generally a bad idea to callsetlocale()in some library routine, since as a side effect it affects the entire program. Saving and restoring it is almost as bad: it is expensive and affects other threads that happen to run before the settings have been restored.

If, when coding a module for general use, you need a locale independent version of an operation that is affected by the locale (such as certain formats used withtime.strftime()), you will have to find a way to do it without using the standard library routine. Even better is convincing yourself that using locale settings is okay. Only as a last resort should you document that your module is not compatible with non-Clocale settings.

The only way to perform numeric operations according to the locale is to use the special functions defined by this module:atof(),atoi(), format_string(),str().

There is no way to perform case conversions and character classifications according to the locale. For (Unicode) text strings these are done according to the character value only, while for byte strings, the conversions and classifications are done according to the ASCII value of the byte, and bytes whose high bit is set (i.e., non-ASCII bytes) are never converted or considered part of a character class such as letter or whitespace.

For extension writers and programs that embed Python

Extension modules should never callsetlocale(),except to find out what the current locale is. But since the return value can only be used portably to restore it, that is not very useful (except perhaps to find out whether or not the locale isC).

When Python code uses thelocalemodule to change the locale, this also affects the embedding application. If the embedding application doesn’t want this to happen, it should remove the_localeextension module (which does all the work) from the table of built-in modules in theconfig.cfile, and make sure that the_localemodule is not accessible as a shared library.

Access to message catalogs

locale.gettext(msg)

locale.dgettext(domain,msg)

locale.dcgettext(domain,msg,category)

locale.textdomain(domain)

locale.bindtextdomain(domain,dir)

locale.bind_textdomain_codeset(domain,codeset)

The locale module exposes the C library’s gettext interface on systems that provide this interface. It consists of the functionsgettext(), dgettext(),dcgettext(),textdomain(),bindtextdomain(), andbind_textdomain_codeset().These are similar to the same functions in thegettextmodule, but use the C library’s binary format for message catalogs, and the C library’s search algorithms for locating message catalogs.

Python applications should normally find no need to invoke these functions, and should usegettextinstead. A known exception to this rule are applications that link with additional C libraries which internally invoke C functionsgettextordcgettext.For these applications, it may be necessary to bind the text domain, so that the libraries can properly locate their message catalogs.