306 lines
12 KiB
Python
306 lines
12 KiB
Python
from __future__ import annotations
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import decimal
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from typing import TYPE_CHECKING
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from babel.core import Locale
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from babel.numbers import LC_NUMERIC, format_decimal
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if TYPE_CHECKING:
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from typing_extensions import Literal
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class UnknownUnitError(ValueError):
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def __init__(self, unit: str, locale: Locale) -> None:
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ValueError.__init__(self, f"{unit} is not a known unit in {locale}")
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def get_unit_name(
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measurement_unit: str,
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length: Literal['short', 'long', 'narrow'] = 'long',
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locale: Locale | str | None = LC_NUMERIC,
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) -> str | None:
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"""
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Get the display name for a measurement unit in the given locale.
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>>> get_unit_name("radian", locale="en")
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'radians'
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Unknown units will raise exceptions:
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>>> get_unit_name("battery", locale="fi")
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Traceback (most recent call last):
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...
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UnknownUnitError: battery/long is not a known unit/length in fi
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:param measurement_unit: the code of a measurement unit.
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Known units can be found in the CLDR Unit Validity XML file:
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https://unicode.org/repos/cldr/tags/latest/common/validity/unit.xml
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:param length: "short", "long" or "narrow"
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:param locale: the `Locale` object or locale identifier
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:return: The unit display name, or None.
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"""
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locale = Locale.parse(locale)
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unit = _find_unit_pattern(measurement_unit, locale=locale)
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if not unit:
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raise UnknownUnitError(unit=measurement_unit, locale=locale)
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return locale.unit_display_names.get(unit, {}).get(length)
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def _find_unit_pattern(unit_id: str, locale: Locale | str | None = LC_NUMERIC) -> str | None:
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"""
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Expand a unit into a qualified form.
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Known units can be found in the CLDR Unit Validity XML file:
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https://unicode.org/repos/cldr/tags/latest/common/validity/unit.xml
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>>> _find_unit_pattern("radian", locale="en")
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'angle-radian'
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Unknown values will return None.
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>>> _find_unit_pattern("horse", locale="en")
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:param unit_id: the code of a measurement unit.
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:return: A key to the `unit_patterns` mapping, or None.
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"""
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locale = Locale.parse(locale)
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unit_patterns = locale._data["unit_patterns"]
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if unit_id in unit_patterns:
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return unit_id
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for unit_pattern in sorted(unit_patterns, key=len):
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if unit_pattern.endswith(unit_id):
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return unit_pattern
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return None
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def format_unit(
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value: str | float | decimal.Decimal,
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measurement_unit: str,
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length: Literal['short', 'long', 'narrow'] = 'long',
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format: str | None = None,
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locale: Locale | str | None = LC_NUMERIC,
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) -> str:
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"""Format a value of a given unit.
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Values are formatted according to the locale's usual pluralization rules
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and number formats.
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>>> format_unit(12, 'length-meter', locale='ro_RO')
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u'12 metri'
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>>> format_unit(15.5, 'length-mile', locale='fi_FI')
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u'15,5 mailia'
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>>> format_unit(1200, 'pressure-millimeter-ofhg', locale='nb')
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u'1\\xa0200 millimeter kvikks\\xf8lv'
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>>> format_unit(270, 'ton', locale='en')
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u'270 tons'
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Number formats may be overridden with the ``format`` parameter.
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>>> import decimal
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>>> format_unit(decimal.Decimal("-42.774"), 'temperature-celsius', 'short', format='#.0', locale='fr')
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u'-42,8\\u202f\\xb0C'
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The locale's usual pluralization rules are respected.
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>>> format_unit(1, 'length-meter', locale='ro_RO')
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u'1 metru'
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>>> format_unit(0, 'length-mile', locale='cy')
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u'0 mi'
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>>> format_unit(1, 'length-mile', locale='cy')
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u'1 filltir'
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>>> format_unit(3, 'length-mile', locale='cy')
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u'3 milltir'
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>>> format_unit(15, 'length-horse', locale='fi')
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Traceback (most recent call last):
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...
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UnknownUnitError: length-horse is not a known unit in fi
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.. versionadded:: 2.2.0
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:param value: the value to format. If this is a string, no number formatting will be attempted.
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:param measurement_unit: the code of a measurement unit.
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Known units can be found in the CLDR Unit Validity XML file:
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https://unicode.org/repos/cldr/tags/latest/common/validity/unit.xml
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:param length: "short", "long" or "narrow"
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:param format: An optional format, as accepted by `format_decimal`.
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:param locale: the `Locale` object or locale identifier
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"""
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locale = Locale.parse(locale)
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q_unit = _find_unit_pattern(measurement_unit, locale=locale)
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if not q_unit:
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raise UnknownUnitError(unit=measurement_unit, locale=locale)
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unit_patterns = locale._data["unit_patterns"][q_unit].get(length, {})
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if isinstance(value, str): # Assume the value is a preformatted singular.
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formatted_value = value
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plural_form = "one"
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else:
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formatted_value = format_decimal(value, format, locale)
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plural_form = locale.plural_form(value)
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if plural_form in unit_patterns:
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return unit_patterns[plural_form].format(formatted_value)
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# Fall back to a somewhat bad representation.
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# nb: This is marked as no-cover, as the current CLDR seemingly has no way for this to happen.
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fallback_name = get_unit_name(measurement_unit, length=length, locale=locale) # pragma: no cover
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return f"{formatted_value} {fallback_name or measurement_unit}" # pragma: no cover
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def _find_compound_unit(
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numerator_unit: str,
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denominator_unit: str,
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locale: Locale | str | None = LC_NUMERIC,
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) -> str | None:
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"""
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Find a predefined compound unit pattern.
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Used internally by format_compound_unit.
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>>> _find_compound_unit("kilometer", "hour", locale="en")
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'speed-kilometer-per-hour'
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>>> _find_compound_unit("mile", "gallon", locale="en")
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'consumption-mile-per-gallon'
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If no predefined compound pattern can be found, `None` is returned.
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>>> _find_compound_unit("gallon", "mile", locale="en")
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>>> _find_compound_unit("horse", "purple", locale="en")
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:param numerator_unit: The numerator unit's identifier
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:param denominator_unit: The denominator unit's identifier
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:param locale: the `Locale` object or locale identifier
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:return: A key to the `unit_patterns` mapping, or None.
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:rtype: str|None
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"""
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locale = Locale.parse(locale)
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# Qualify the numerator and denominator units. This will turn possibly partial
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# units like "kilometer" or "hour" into actual units like "length-kilometer" and
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# "duration-hour".
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resolved_numerator_unit = _find_unit_pattern(numerator_unit, locale=locale)
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resolved_denominator_unit = _find_unit_pattern(denominator_unit, locale=locale)
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# If either was not found, we can't possibly build a suitable compound unit either.
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if not (resolved_numerator_unit and resolved_denominator_unit):
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return None
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# Since compound units are named "speed-kilometer-per-hour", we'll have to slice off
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# the quantities (i.e. "length", "duration") from both qualified units.
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bare_numerator_unit = resolved_numerator_unit.split("-", 1)[-1]
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bare_denominator_unit = resolved_denominator_unit.split("-", 1)[-1]
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# Now we can try and rebuild a compound unit specifier, then qualify it:
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return _find_unit_pattern(f"{bare_numerator_unit}-per-{bare_denominator_unit}", locale=locale)
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def format_compound_unit(
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numerator_value: str | float | decimal.Decimal,
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numerator_unit: str | None = None,
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denominator_value: str | float | decimal.Decimal = 1,
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denominator_unit: str | None = None,
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length: Literal["short", "long", "narrow"] = "long",
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format: str | None = None,
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locale: Locale | str | None = LC_NUMERIC,
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) -> str | None:
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"""
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Format a compound number value, i.e. "kilometers per hour" or similar.
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Both unit specifiers are optional to allow for formatting of arbitrary values still according
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to the locale's general "per" formatting specifier.
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>>> format_compound_unit(7, denominator_value=11, length="short", locale="pt")
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'7/11'
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>>> format_compound_unit(150, "kilometer", denominator_unit="hour", locale="sv")
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'150 kilometer per timme'
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>>> format_compound_unit(150, "kilowatt", denominator_unit="year", locale="fi")
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'150 kilowattia / vuosi'
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>>> format_compound_unit(32.5, "ton", 15, denominator_unit="hour", locale="en")
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'32.5 tons per 15 hours'
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>>> format_compound_unit(160, denominator_unit="square-meter", locale="fr")
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'160 par m\\xe8tre carr\\xe9'
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>>> format_compound_unit(4, "meter", "ratakisko", length="short", locale="fi")
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'4 m/ratakisko'
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>>> format_compound_unit(35, "minute", denominator_unit="fathom", locale="sv")
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'35 minuter per famn'
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>>> from babel.numbers import format_currency
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>>> format_compound_unit(format_currency(35, "JPY", locale="de"), denominator_unit="liter", locale="de")
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'35\\xa0\\xa5 pro Liter'
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See https://www.unicode.org/reports/tr35/tr35-general.html#perUnitPatterns
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:param numerator_value: The numerator value. This may be a string,
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in which case it is considered preformatted and the unit is ignored.
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:param numerator_unit: The numerator unit. See `format_unit`.
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:param denominator_value: The denominator value. This may be a string,
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in which case it is considered preformatted and the unit is ignored.
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:param denominator_unit: The denominator unit. See `format_unit`.
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:param length: The formatting length. "short", "long" or "narrow"
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:param format: An optional format, as accepted by `format_decimal`.
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:param locale: the `Locale` object or locale identifier
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:return: A formatted compound value.
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"""
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locale = Locale.parse(locale)
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# Look for a specific compound unit first...
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if numerator_unit and denominator_unit and denominator_value == 1:
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compound_unit = _find_compound_unit(numerator_unit, denominator_unit, locale=locale)
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if compound_unit:
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return format_unit(numerator_value, compound_unit, length=length, format=format, locale=locale)
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# ... failing that, construct one "by hand".
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if isinstance(numerator_value, str): # Numerator is preformatted
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formatted_numerator = numerator_value
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elif numerator_unit: # Numerator has unit
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formatted_numerator = format_unit(
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numerator_value, numerator_unit, length=length, format=format, locale=locale
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)
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else: # Unitless numerator
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formatted_numerator = format_decimal(numerator_value, format=format, locale=locale)
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if isinstance(denominator_value, str): # Denominator is preformatted
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formatted_denominator = denominator_value
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elif denominator_unit: # Denominator has unit
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if denominator_value == 1: # support perUnitPatterns when the denominator is 1
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denominator_unit = _find_unit_pattern(denominator_unit, locale=locale)
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per_pattern = locale._data["unit_patterns"].get(denominator_unit, {}).get(length, {}).get("per")
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if per_pattern:
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return per_pattern.format(formatted_numerator)
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# See TR-35's per-unit pattern algorithm, point 3.2.
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# For denominator 1, we replace the value to be formatted with the empty string;
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# this will make `format_unit` return " second" instead of "1 second".
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denominator_value = ""
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formatted_denominator = format_unit(
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denominator_value,
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measurement_unit=(denominator_unit or ""),
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length=length,
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format=format,
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locale=locale,
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).strip()
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else: # Bare denominator
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formatted_denominator = format_decimal(denominator_value, format=format, locale=locale)
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# TODO: this doesn't support "compound_variations" (or "prefix"), and will fall back to the "x/y" representation
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per_pattern = locale._data["compound_unit_patterns"].get("per", {}).get(length, {}).get("compound", "{0}/{1}")
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return per_pattern.format(formatted_numerator, formatted_denominator)
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