Struct Locale 

#[non_exhaustive]
pub struct Locale {

    pub tag: String,
    pub decimal_mark: String,
    pub big_mark: String,
    pub min_grouping_digits: usize,
    pub currency_symbol: String,
    pub currency_position: CurrencyPosition,
    pub currency_spacing: String,
    pub percent_suffix: String,
    pub months_short: [String; 12],
    pub months_long: [String; 12],
    pub days_short: [String; 7],
    pub days_long: [String; 7],
    pub date_format: String,
    pub month_format: String,
    pub time_format: String,
}

Number and date formatting conventions of a locale.

Construct one with a preset (en_us, de_de, fr_fr, en_gb) or from_tag, then adjust the public fields or use the with_* builders. The struct is #[non_exhaustive] so new conventions can be added without a breaking change.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

tag: String

Canonical BCP-47 tag of the preset, e.g. "de-DE".

decimal_mark: String

Decimal mark ("." / ",").

big_mark: String

Thousands separator (",", ".", " ", "'"; "" disables grouping).

min_grouping_digits: usize

Group thousands only when the integer part has at least 3 + min_grouping_digits digits (CLDR’s minimum grouping digits). 1 (every preset) groups 1000 as 1.000; 2 leaves 2020 alone and groups from 10.000.

currency_symbol: String

The locale’s currency symbol ("$", "€", "£").

currency_position: CurrencyPosition

Where the currency symbol goes.

currency_spacing: String

Text between amount and currency symbol ("" or " ").

percent_suffix: String

Suffix of percentages ("%" in English, " %" in German / French).

months_short: [String; 12]

Abbreviated month names, January first (%b).

months_long: [String; 12]

Full month names, January first (%B).

days_short: [String; 7]

Abbreviated weekday names, Sunday first (%a).

days_long: [String; 7]

Full weekday names, Sunday first (%A).

date_format: String

strftime format of a calendar date (default date-axis labels at day resolution), e.g. "%-d. %b %Y" → 15. Okt. 2026.

month_format: String

strftime format of a month (default monthly date-axis labels), e.g. "%b %Y" → Okt. 2026.

time_format: String

strftime format of a time of day, appended to the date for datetimes that are not at midnight, e.g. "%H:%M".

Implementations

impl Locale

pub fn en_us() -> Self

English (United States): 1,234.5, $1,234.50, 50%, Oct 15, 2026.

pub fn en_gb() -> Self

English (United Kingdom): 1,234.5, £1,234.50, 50%, 15 Oct 2026.

pub fn de_de() -> Self

German (Germany): 1.234,5, 1.234,50 €, 50 %, 15. Okt. 2026.

pub fn fr_fr() -> Self

French (France): 1 234,5, 1 234,50 €, 50 %, 15 oct. 2026. The thousands mark is a plain space (CLDR uses a narrow no-break space, which many fonts lack); set big_mark to override.

pub fn try_from_tag(tag: &str) -> Option<Self>

The preset for a BCP-47-ish tag, if one matches: case-insensitive, - or _ separated, POSIX suffixes (.UTF-8, @euro) ignored. de* → de_de, fr* → fr_fr, en-GB / en-UK → en_gb, other en* and C / POSIX → en_us.

pub fn from_tag(tag: &str) -> Self

Like try_from_tag, falling back to en_us for unknown tags.

use ggplot_rs::locale::Locale;
assert_eq!(Locale::from_tag("de-DE").tag, "de-DE");
assert_eq!(Locale::from_tag("fr_FR.UTF-8").tag, "fr-FR");
assert_eq!(Locale::from_tag("en-GB").tag, "en-GB");
assert_eq!(Locale::from_tag("xx-YY").tag, "en-US");

pub fn with_decimal_mark(self, mark: &str) -> Self

Replace the decimal mark.

pub fn with_big_mark(self, mark: &str) -> Self

Replace the thousands mark ("" disables grouping).

pub fn with_min_grouping_digits(self, digits: usize) -> Self

Replace the minimum grouping digits (see min_grouping_digits).

pub fn with_currency(self, symbol: &str) -> Self

Use another currency symbol, placed by this locale’s convention: Locale::de_de().with_currency("CHF") formats 1.234,50 CHF.

pub fn currency_affixes(&self, symbol: &str) -> (String, String)

(prefix, suffix) that place symbol by this locale’s convention: ("$", "") for en-US, ("", " €") for de-DE.

pub fn localize_number(&self, s: &str) -> String

Re-render a number formatted the default way (. decimal mark, , or no thousands grouping, optional leading -) with this locale’s marks: "-1234.5" / "-1,234.5" → "-1.234,5" in de-DE. Anything that is not such a number (NaN, inf, text) is returned unchanged.

pub fn parse_number(&self, s: &str) -> Option<f64>

Inverse of localize_number for parsing a label back to a number: strips thousands marks and restores ..

pub fn format_number(&self, v: f64) -> String

Format a break value like the default axis labels (integers verbatim, otherwise up to two decimals, trailing zeros trimmed) with this locale’s marks: 1234.5 → "1.234,5" in de-DE.

pub fn strftime(&self, epoch_secs: i64, fmt: &str) -> String

Format epoch seconds (UTC) with a strftime-style format, using this locale’s month and weekday names. Supported: %Y %y %m %-m %b %B %d %-d %e %a %A %H %M %S %%.

pub fn format_datetime(&self, epoch_secs: i64) -> String

Format epoch seconds (UTC) as this locale’s date (date_format), plus time_format when not at midnight.

Trait Implementations

impl Clone for Locale

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Locale

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Locale

fn default() -> Self

Locale::en_us.

impl FromStr for Locale

fn from_str(s: &str) -> Result<Self, Self::Err>

Locale::from_tag (never fails; unknown tags give en-US).

type Err = !

The associated error which can be returned from parsing.

impl PartialEq for Locale

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Locale