View Source Cldr.Number (Cldr Numbers v2.33.1)
Formats numbers and currencies based upon CLDR's decimal formats specification.
The format specification is documentated in Unicode TR35.
There are several classes of formatting including non-scientific, scientific,
rules based (for spelling and ordinal formats), compact formats that display 1k
rather than 1,000
and so on. See Cldr.Number.to_string/2
for specific formatting
options.
Non-Scientific Notation Formatting
The following description applies to formats that do not use scientific notation or significant digits:
If the number of actual integer digits exceeds the maximum integer digits, then only the least significant digits are shown. For example, 1997 is formatted as "97" if the maximum integer digits is set to 2.
If the number of actual integer digits is less than the minimum integer digits, then leading zeros are added. For example, 1997 is formatted as "01997" if the minimum integer digits is set to 5.
If the number of actual fraction digits exceeds the maximum fraction digits, then half-even rounding it performed to the maximum fraction digits. For example, 0.125 is formatted as "0.12" if the maximum fraction digits is 2. This behavior can be changed by specifying a rounding increment and a rounding mode.
If the number of actual fraction digits is less than the minimum fraction digits, then trailing zeros are added. For example, 0.125 is formatted as "0.1250" if the minimum fraction digits is set to 4.
Trailing fractional zeros are not displayed if they occur j positions after the decimal, where j is less than the maximum fraction digits. For example, 0.10004 is formatted as "0.1" if the maximum fraction digits is four or less.
Scientific Notation Formatting
Numbers in scientific notation are expressed as the product of a mantissa and a power of ten, for example, 1234 can be expressed as 1.234 x 10^3. The mantissa is typically in the half-open interval [1.0, 10.0) or sometimes [0.0, 1.0), but it need not be. In a pattern, the exponent character immediately followed by one or more digit characters indicates scientific notation. Example: "0.###E0" formats the number 1234 as "1.234E3".
The number of digit characters after the exponent character gives the minimum exponent digit count. There is no maximum. Negative exponents are formatted using the localized minus sign, not the prefix and suffix from the pattern. This allows patterns such as "0.###E0 m/s". To prefix positive exponents with a localized plus sign, specify '+' between the exponent and the digits: "0.###E+0" will produce formats "1E+1", "1E+0", "1E-1", and so on. (In localized patterns, use the localized plus sign rather than '+'.)
The minimum number of integer digits is achieved by adjusting the exponent. Example: 0.00123 formatted with "00.###E0" yields "12.3E-4". This only happens if there is no maximum number of integer digits. If there is a maximum, then the minimum number of integer digits is fixed at one.
The maximum number of integer digits, if present, specifies the exponent grouping. The most common use of this is to generate engineering notation, in which the exponent is a multiple of three, for example, "##0.###E0". The number 12345 is formatted using "##0.####E0" as "12.345E3".
When using scientific notation, the formatter controls the digit counts using significant digits logic. The maximum number of significant digits limits the total number of integer and fraction digits that will be shown in the mantissa; it does not affect parsing. For example, 12345 formatted with "##0.##E0" is "12.3E3". Exponential patterns may not contain grouping separators.
Significant Digits
There are two ways of controlling how many digits are shows: (a) significant digits counts, or (b) integer and fraction digit counts. Integer and fraction digit counts are described above. When a formatter is using significant digits counts, it uses however many integer and fraction digits are required to display the specified number of significant digits. It may ignore min/max integer/fraction digits, or it may use them to the extent possible.
Summary
Functions
Returns the metadata representing the given format.
Return the precision (number of digits) of a number
Formats a number and applies the :approximately
format for
a locale and number system.
Formats a number and applies the :at_least
format for
a locale and number system.
Formats a number and applies the :at_most
format for
a locale and number system.
Converts a number from the latin digits 0..9
into
another number system. Returns {:ok, string}
or
{:error, reason}
.
Converts a number from the latin digits 0..9
into
another number system. Returns the converted number
or raises an exception on error.
Formats the first and last numbers of a range and applies
the :range
format for a locale and number system.
Returns a number formatted into a string according to a format pattern and options.
Same as the execution of to_string/2
but raises an exception if an error would be
returned.
Return a valid number system from a provided locale and number system name or type.
Types
@type format_type() ::
:standard
| :decimal_short
| :decimal_long
| :currency_short
| :currency_long
| :percent
| :accounting
| :scientific
| :currency
Functions
@spec decimal_format_metadata(String.t(), Cldr.backend()) :: {:ok, Cldr.Number.Format.Meta.t()} | {:error, String.t()}
Returns the metadata representing the given format.
Return the precision (number of digits) of a number
This function delegates to Cldr.Digits.number_of_digits/1
Example
iex> Cldr.Number.precision 1.234
4
to_approx_string(number, backend \\ default_backend(), options \\ [])
View Source@spec to_approx_string(number() | Decimal.t(), Cldr.backend(), Keyword.t() | map()) :: {:ok, String.t()} | {:error, {module(), String.t()}}
Formats a number and applies the :approximately
format for
a locale and number system.
Arguments
number
is an integer, float or Decimal to be formattedbackend
is anyCldr
backend. That is, any module that containsuse Cldr
options
is a keyword list defining how the number is to be formatted. SeeCldr.Number.to_string/3
for a description of the available options.
Example
iex> Cldr.Number.to_approx_string 1234, TestBackend.Cldr
{:ok, "~1,234"}
to_at_least_string(number, backend \\ default_backend(), options \\ [])
View Source@spec to_at_least_string(number() | Decimal.t(), Cldr.backend(), Keyword.t() | map()) :: {:ok, String.t()} | {:error, {module(), String.t()}}
Formats a number and applies the :at_least
format for
a locale and number system.
Arguments
number
is an integer, float or Decimal to be formattedbackend
is anyCldr
backend. That is, any module that containsuse Cldr
options
is a keyword list defining how the number is to be formatted. SeeCldr.Number.to_string/3
for a description of the available options.
Example
iex> Cldr.Number.to_at_least_string 1234, TestBackend.Cldr
{:ok, "1,234+"}
to_at_most_string(number, backend \\ default_backend(), options \\ [])
View Source@spec to_at_most_string(number() | Decimal.t(), Cldr.backend(), Keyword.t() | map()) :: {:ok, String.t()} | {:error, {module(), String.t()}}
Formats a number and applies the :at_most
format for
a locale and number system.
Arguments
number
is an integer, float or Decimal to be formattedbackend
is anyCldr
backend. That is, any module that containsuse Cldr
options
is a keyword list defining how the number is to be formatted. SeeCldr.Number.to_string/3
for a description of the available options.
Example
iex> Cldr.Number.to_at_most_string 1234, TestBackend.Cldr
{:ok, "≤1,234"}
@spec to_number_system(number(), atom(), Cldr.backend()) :: String.t() | {:error, {module(), String.t()}}
Converts a number from the latin digits 0..9
into
another number system. Returns {:ok, string}
or
{:error, reason}
.
number
is an integer, float. Decimal is supported only for:numeric
number systems, not:algorithmic
. SeeCldr.Number.System.to_system/3
for further information.system
is any number system returned byCldr.known_number_systems/0
Examples
iex> Cldr.Number.to_number_system 123, :hant, TestBackend.Cldr
{:ok, "一百二十三"}
iex> Cldr.Number.to_number_system 123, :hebr, TestBackend.Cldr
{:ok, "קכ״ג"}
@spec to_number_system!(number(), atom(), Cldr.backend()) :: String.t() | no_return()
Converts a number from the latin digits 0..9
into
another number system. Returns the converted number
or raises an exception on error.
number
is an integer, float. Decimal is supported only for:numeric
number systems, not:algorithmic
. SeeCldr.Number.System.to_system/3
for further information.system
is any number system returned byCldr.Number.System.known_number_systems/0
Example
iex> Cldr.Number.to_number_system! 123, :hant, TestBackend.Cldr
"一百二十三"
to_range_string(number, backend \\ default_backend(), options \\ [])
View Source@spec to_range_string(Range.t(), Cldr.backend(), Keyword.t() | map()) :: {:ok, String.t()} | {:error, {module(), String.t()}}
Formats the first and last numbers of a range and applies
the :range
format for a locale and number system.
Arguments
number
is an integer, float or Decimal to be formattedbackend
is anyCldr
backend. That is, any module that containsuse Cldr
options
is a keyword list defining how the number is to be formatted. SeeCldr.Number.to_string/3
for a description of the available options.
Example
iex> Cldr.Number.to_range_string 1234..5678, TestBackend.Cldr
{:ok, "1,234–5,678"}
@spec to_string( number() | Decimal.t() | String.t(), Cldr.backend() | Keyword.t() | map(), Keyword.t() | map() ) :: {:ok, String.t()} | {:error, {atom(), String.t()}}
Returns a number formatted into a string according to a format pattern and options.
Arguments
number
is an integer, float or Decimal to be formattedbackend
is anyCldr
backend. That is, any module that containsuse Cldr
options
is a keyword list defining how the number is to be formatted. The valid options are:
Options
format
: the format style or a format string defining how the number is formatted. SeeCldr.Number.Format
for how format strings can be constructed. SeeCldr.Number.Format.format_styles_for/3
to return available format styles for a locale. The defaultformat
is:standard
.If
:format
is set to:long
or:short
then the formatting depends on whether:currency
is specified. If not specified then the number is formatted as:decimal_long
or:decimal_short
. If:currency
is specified the number is formatted as:currency_long
or:currency_short
and:fractional_digits
is set to 0 as a default.If
:format
is set to:currency_long_with_symbol
then a format composed of:currency_long
with the locale's currency format is used.:format
may also be a format defined by CLDR's Rules Based Number Formats (RBNF). Further information is found in the moduleCldr.Rbnf
. The most commonly used formats in this category are to spell out the number in a the locales language. The applicable formats are:spellout
,:spellout_year
,:ordinal
. A number can also be formatted as roman numbers by using the format:roman
or:roman_lower
.currency
: is the currency for which the number is formatted. Ifcurrency
is set and no:format
is set,:format
will be set to:currency
as well. Currency may be any ISO 4217 currency code returned byCldr.Currency.known_currencies/0
or a ISO 24165 digital token identifier (crypto currency).currency_symbol
: Allows overriding a currency symbol. The alternatives are::iso
the ISO currency code will be used instead of the default currency symbol.:narrow
uses the narrow symbol defined for the locale. The same narrow symbol can be defined for more than one currency and therefore this should be used with care. If no narrow symbol is defined, the standard symbol is used.:symbol
uses the standard symbol defined in CLDR. A symbol is unique for each currency and can be safely used.:standard
(the default and recommended) uses the CLDR-defined symbol based upon the currency format for the locale.- "string" uses
string
as the currency symbol
:cash
: a boolean which indicates whether a number being formatted as a:currency
is to be considered a cash value or not. Currencies can be rounded differently depending on whether:cash
istrue
orfalse
. *This option is deprecated in favour ofcurrency_digits: :cash
. Ignored if the currency is a digital token.:currency_digits
indicates which of the rounding and digits should be used. The options are:accounting
which is the default,:cash
or:iso
. Ignored if the currency is a digital token.:rounding_mode
: determines how a number is rounded to meet the precision of the format requested. The available rounding modes are:down
, :half_up, :half_even, :ceiling, :floor, :half_down, :up. The default is:half_even
.:number_system
: determines which of the number systems for a locale should be used to define the separators and digits for the formatted number. Ifnumber_system
is anatom
thennumber_system
is interpreted as a number system. SeeCldr.Number.System.number_systems_for/2
. If the:number_system
isbinary
then it is interpreted as a number system name. SeeCldr.Number.System.number_system_names_for/2
. The default is:default
.:locale
: determines the locale in which the number is formatted. SeeCldr.known_locale_names/0
. The default isCldr.get_locale/0
which is the locale currently in affect for thisProcess
and which is set byCldr.put_locale/1
.If
:fractional_digits
is set to a positive integer value then the number will be rounded to that number of digits and displayed accordingly - overriding settings that would be applied by default. For example, currencies have fractional digits defined reflecting each currencies minor unit. Setting:fractional_digits
will override that setting.If
:maximum_integer_digits
is set to a positive integer value then the number is left truncated before formatting. For example if the number1234
is formatted with the optionmaximum_integer_digits: 2
, the number is truncated to34
and formatted.If
:round_nearest
is set to a positive integer value then the number will be rounded to nearest increment of that value - overriding settings that would be applied by default.:minimum_grouping_digits
overrides the CLDR definition of minimum grouping digits. For example in the localees
the number1345
is formatted by default as1345
because the locale defines theminimium_grouping_digits
as2
. Ifminimum_grouping_digits: 1
is set as an option the number is formatted as1.345
. The:minimum_grouping_digits
is added to the grouping defined by the number format. If the sum of these two digits is greater than the number of digits in the integer (or fractional) part of the number then no grouping is performed.:wrapper
is a 2-arity function that will be called for each number component with parametersstring
andtag
wheretag
is one of:number
,:currency_symbol
,:currency_space
,:literal
,:quote
,:percent
,:permille
,:minus
or:plus
. The function must return either a string or a Phoenix safe string such as that returned byPhoenix.HTML.Tag.content_tag/3
. The function can be used to wrap format elements in HTML or other tags.
Locale extensions affecting formatting
A locale identifier can specify options that affect number formatting. These options are:
nu
: defines the number system to be used if none is specified by the:number_system
option toto_string/2
This key is part of the u extension and that document should be consulted for details on how to construct a locale identifier with these extensions.
Wrapping format elements
Wrapping elements is particularly useful when formatting a number with a currency symbol and the requirement is to have different HTML formatting applied to the symbol than the number. For example:
iex> Cldr.Number.to_string(100, format: :currency, currency: :USD, wrapper: fn
...> string, :currency_symbol -> "<span class=\"symbol\">" <> string <> "</span>"
...> string, :number -> "<span class=\"number\">" <> string <> "</span>"
...> string, :currency_space -> "<span>" <> string <> "</span>"
...> string, _other -> string
...> end)
{:ok, "<span class=\"symbol\">$</span><span class=\"number\">100.00</span>"}
It is also possible and recommended to use the Phoenix.HTML.Tag.content_tag/3
function if wrapping HTML tags since these will ensure HTML entities are
correctly encoded. For example:
iex> Cldr.Number.to_string(100, format: :currency, currency: :USD, wrapper: fn
...> string, :currency_symbol -> Phoenix.HTML.Tag.content_tag(:span, string, class: "symbol")
...> string, :number -> Phoenix.HTML.Tag.content_tag(:span, string, class: "number")
...> string, :currency_space -> Phoenix.HTML.Tag.content_tag(:span, string)
...> string, _other -> string
...> end)
{:ok, "<span class=\"symbol\">$</span><span class=\"number\">100.00</span>"}
When formatting a number the format is parsed into format elements that might include
a currency symbol, a literal string, inserted text between a currency symbol and the
currency amount, a percent sign, the number itself and several other elements. In
some cases it is helpful to be apply specific formatting to each element.
This can be achieved by specifying a :wrapper
option. This option takes a 2-arity
function as an argument. For each element of the format the wrapper function is called
with two parameters: the format element as a string and an atom representing the
element type. The wrapper function is required to return a string that is then
inserted in the final formatted number.
Returns
{:ok, string}
or{:error, {exception, message}}
Examples
iex> Cldr.Number.to_string 12345, TestBackend.Cldr
{:ok, "12,345"}
iex> Cldr.Number.to_string 12345, TestBackend.Cldr, locale: "fr"
{:ok, "12 345"}
iex> Cldr.Number.to_string 1345.32, TestBackend.Cldr, currency: :EUR, locale: "es", minimum_grouping_digits: 1
{:ok, "1.345,32 €"}
iex> Cldr.Number.to_string 1345.32, TestBackend.Cldr, currency: :EUR, locale: "es"
{:ok, "1345,32 €"}
iex> Cldr.Number.to_string 12345, TestBackend.Cldr, locale: "fr", currency: "USD"
{:ok, "12 345,00 $US"}
iex> Cldr.Number.to_string 12345, TestBackend.Cldr, format: "#E0"
{:ok, "1.2345E4"}
iex> Cldr.Number.to_string 12345, TestBackend.Cldr, format: :accounting, currency: "THB"
{:ok, "THB 12,345.00"}
iex> Cldr.Number.to_string -12345, TestBackend.Cldr, format: :accounting, currency: "THB"
{:ok, "(THB 12,345.00)"}
iex> Cldr.Number.to_string 12345, TestBackend.Cldr, format: :accounting, currency: "THB",
...> locale: "th"
{:ok, "฿12,345.00"}
iex> Cldr.Number.to_string 12345, TestBackend.Cldr, format: :accounting, currency: "THB",
...> locale: "th", number_system: :native
{:ok, "฿๑๒,๓๔๕.๐๐"}
iex> Cldr.Number.to_string 1244.30, TestBackend.Cldr, format: :long
{:ok, "1 thousand"}
iex> Cldr.Number.to_string 1244.30, TestBackend.Cldr, format: :long, currency: "USD"
{:ok, "1,244 US dollars"}
iex> Cldr.Number.to_string 1244.30, TestBackend.Cldr, format: :short
{:ok, "1K"}
iex> Cldr.Number.to_string 1244.30, TestBackend.Cldr, format: :short, currency: "EUR"
{:ok, "€1K"}
iex> Cldr.Number.to_string 1234, TestBackend.Cldr, format: :spellout
{:ok, "one thousand two hundred thirty-four"}
iex> Cldr.Number.to_string 1234, TestBackend.Cldr, format: :spellout_verbose
{:ok, "one thousand two hundred and thirty-four"}
iex> Cldr.Number.to_string 1989, TestBackend.Cldr, format: :spellout_year
{:ok, "nineteen eighty-nine"}
iex> Cldr.Number.to_string 123, TestBackend.Cldr, format: :ordinal
{:ok, "123rd"}
iex> Cldr.Number.to_string 123, TestBackend.Cldr, format: :roman
{:ok, "CXXIII"}
iex> Cldr.Number.to_string 123, TestBackend.Cldr, locale: "th-u-nu-thai"
{:ok, "๑๒๓"}
Errors
An error tuple {:error, {exception, reason}}
will be returned if an error is detected.
The two most likely causes of an error return are:
- A format cannot be compiled. In this case the error tuple will look like:
iex> Cldr.Number.to_string(12345, TestBackend.Cldr, format: "0#")
{:error, {Cldr.FormatCompileError,
"Decimal format compiler: syntax error before: \"#\""}}
- The format style requested is not defined for the
locale
andnumber_system
. This happens typically when the number system is:algorithmic
rather than the more common:numeric
. In this case the error return looks like:
iex> Cldr.Number.to_string(1234, TestBackend.Cldr, locale: "he", number_system: "hebr", format: :percent)
{:error, {Cldr.UnknownFormatError,
"The locale :he with number system :hebr does not define a format :percent"}}
@spec to_string!( number() | Decimal.t() | String.t(), Cldr.backend() | Keyword.t() | map(), Keyword.t() | map() ) :: String.t() | no_return()
Same as the execution of to_string/2
but raises an exception if an error would be
returned.
Options
number
is an integer, float or Decimal to be formattedoptions
is a keyword list defining how the number is to be formatted. SeeCldr.Number.to_string/2
Returns
a formatted number as a string or
raises an exception
Examples
iex> Cldr.Number.to_string! 12345, TestBackend.Cldr
"12,345"
iex> Cldr.Number.to_string! 12345, TestBackend.Cldr, locale: "fr"
"12 345"
validate_number_system(locale, number_system, backend \\ default_backend())
View Source@spec validate_number_system( Cldr.Locale.locale_name() | Cldr.LanguageTag.t(), Cldr.Number.System.system_name() | Cldr.Number.System.types(), Cldr.backend() ) :: {:ok, Cldr.Number.System.system_name()} | {:error, {module(), String.t()}}
Return a valid number system from a provided locale and number system name or type.
The number system or number system type must be valid for the given locale. If a number system type is provided, the underlying number system is returned.
Arguments
locale
is any valid locale name returned byCldr.known_locale_names/1
or aCldr.LanguageTag
struct returned byCldr.Locale.new!/2
system_name
is any number system name returned byCldr.known_number_systems/0
or a number system type returned byCldr.known_number_system_types/0
backend
is any module that includesuse Cldr
and therefore is aCldr
backend module
Examples
iex> Cldr.Number.validate_number_system :en, :latn, TestBackend.Cldr
{:ok, :latn}
iex> Cldr.Number.validate_number_system :en, :default, TestBackend.Cldr
{:ok, :latn}
iex> Cldr.Number.validate_number_system :en, :unknown, TestBackend.Cldr
{:error,
{Cldr.UnknownNumberSystemError, "The number system :unknown is unknown"}}
iex> Cldr.Number.validate_number_system "zz", :default, TestBackend.Cldr
{:error, {Cldr.InvalidLanguageError, "The language \"zz\" is invalid"}}