Module peprock.models.metric_prefix

Metric prefix model.

See https://en.wikipedia.org/wiki/Metric_prefix

Examples

>>> MetricPrefix.mega.convert(5, to=MetricPrefix.kilo)
5000

>>> MetricPrefix.centi.convert(0.7, to=MetricPrefix.milli)
7.0

"""Metric prefix model.

See https://en.wikipedia.org/wiki/Metric_prefix

Examples
--------
>>> MetricPrefix.mega.convert(5, to=MetricPrefix.kilo)
5000

>>> MetricPrefix.centi.convert(0.7, to=MetricPrefix.milli)
7.0

"""

from __future__ import annotations

import enum
import functools
import types
import typing

if typing.TYPE_CHECKING:
    import decimal
    import fractions

    ComplexT = typing.TypeVar(
        "ComplexT",
        float,
        complex,
        decimal.Decimal,
        fractions.Fraction,
    )

_BASE: typing.Final[int] = 10


class MetricPrefix(enum.IntEnum):
    """MetricPrefix IntEnum with symbol and conversion support."""

    quetta = 30
    ronna = 27
    yotta = 24
    zetta = 21
    exa = 18
    peta = 15
    tera = 12
    giga = 9
    mega = 6
    kilo = 3
    hecto = 2
    deca = 1
    NONE = 0
    deci = -1
    centi = -2
    milli = -3
    micro = -6
    nano = -9
    pico = -12
    femto = -15
    atto = -18
    zepto = -21
    yocto = -24
    ronto = -27
    quecto = -30

    @classmethod
    def from_symbol(cls: type[MetricPrefix], symbol: str, /) -> MetricPrefix:
        """Return MetricPrefix by symbol."""
        return cls._by_symbol()[symbol]

    @functools.cached_property
    def symbol(self: MetricPrefix) -> str:
        """Metric prefix symbol, e.g. G for giga."""
        return self._symbols()[self]

    def __str__(self: MetricPrefix) -> str:
        """Return symbol."""
        return self.symbol

    @typing.overload
    def to(
        self: MetricPrefix,
        __other: MetricPrefix | int,
        /,
        *,
        number_type: type[int] = int,
    ) -> int | float:
        ...

    @typing.overload
    def to(
        self: MetricPrefix,
        __other: MetricPrefix | int,
        /,
        *,
        number_type: type[ComplexT],
    ) -> ComplexT:
        ...

    def to(
        self: MetricPrefix,
        __other: MetricPrefix | int,
        /,
        *,
        number_type: type[int | ComplexT] = int,
    ) -> int | ComplexT:
        """Calculate conversion factor between self and other."""
        return number_type(_BASE) ** (self - __other)

    @typing.overload
    def convert(
        self: MetricPrefix,
        __value: int,
        /,
        to: MetricPrefix = NONE,  # type: ignore[assignment]
    ) -> int | float:
        ...

    @typing.overload
    def convert(
        self: MetricPrefix,
        __value: ComplexT,
        /,
        to: MetricPrefix = NONE,  # type: ignore[assignment]
    ) -> ComplexT:
        ...

    def convert(
        self,
        __value,
        /,
        to=NONE,
    ):
        """Convert value from metric prefix self to to."""
        if self is to:
            return __value

        return __value * self.to(to, number_type=type(__value))

    @staticmethod
    @functools.cache
    def _symbols() -> types.MappingProxyType[MetricPrefix, str]:
        return types.MappingProxyType(
            {
                MetricPrefix.quetta: "Q",
                MetricPrefix.ronna: "R",
                MetricPrefix.yotta: "Y",
                MetricPrefix.zetta: "Z",
                MetricPrefix.exa: "E",
                MetricPrefix.peta: "P",
                MetricPrefix.tera: "T",
                MetricPrefix.giga: "G",
                MetricPrefix.mega: "M",
                MetricPrefix.kilo: "k",
                MetricPrefix.hecto: "h",
                MetricPrefix.deca: "da",
                MetricPrefix.NONE: "",
                MetricPrefix.deci: "d",
                MetricPrefix.centi: "c",
                MetricPrefix.milli: "m",
                MetricPrefix.micro: "μ",
                MetricPrefix.nano: "n",
                MetricPrefix.pico: "p",
                MetricPrefix.femto: "f",
                MetricPrefix.atto: "a",
                MetricPrefix.zepto: "z",
                MetricPrefix.yocto: "y",
                MetricPrefix.ronto: "r",
                MetricPrefix.quecto: "q",
            },
        )

    @classmethod
    @functools.cache
    def _by_symbol(
        cls: type[MetricPrefix],
    ) -> types.MappingProxyType[str, MetricPrefix]:
        return types.MappingProxyType(
            {symbol: metric_prefix for metric_prefix, symbol in cls._symbols().items()},
        )


__all__ = [
    "MetricPrefix",
]

Classes

class MetricPrefix (value, names=None, *, module=None, qualname=None, type=None, start=1)

MetricPrefix IntEnum with symbol and conversion support.

Expand source code

class MetricPrefix(enum.IntEnum):
    """MetricPrefix IntEnum with symbol and conversion support."""

    quetta = 30
    ronna = 27
    yotta = 24
    zetta = 21
    exa = 18
    peta = 15
    tera = 12
    giga = 9
    mega = 6
    kilo = 3
    hecto = 2
    deca = 1
    NONE = 0
    deci = -1
    centi = -2
    milli = -3
    micro = -6
    nano = -9
    pico = -12
    femto = -15
    atto = -18
    zepto = -21
    yocto = -24
    ronto = -27
    quecto = -30

    @classmethod
    def from_symbol(cls: type[MetricPrefix], symbol: str, /) -> MetricPrefix:
        """Return MetricPrefix by symbol."""
        return cls._by_symbol()[symbol]

    @functools.cached_property
    def symbol(self: MetricPrefix) -> str:
        """Metric prefix symbol, e.g. G for giga."""
        return self._symbols()[self]

    def __str__(self: MetricPrefix) -> str:
        """Return symbol."""
        return self.symbol

    @typing.overload
    def to(
        self: MetricPrefix,
        __other: MetricPrefix | int,
        /,
        *,
        number_type: type[int] = int,
    ) -> int | float:
        ...

    @typing.overload
    def to(
        self: MetricPrefix,
        __other: MetricPrefix | int,
        /,
        *,
        number_type: type[ComplexT],
    ) -> ComplexT:
        ...

    def to(
        self: MetricPrefix,
        __other: MetricPrefix | int,
        /,
        *,
        number_type: type[int | ComplexT] = int,
    ) -> int | ComplexT:
        """Calculate conversion factor between self and other."""
        return number_type(_BASE) ** (self - __other)

    @typing.overload
    def convert(
        self: MetricPrefix,
        __value: int,
        /,
        to: MetricPrefix = NONE,  # type: ignore[assignment]
    ) -> int | float:
        ...

    @typing.overload
    def convert(
        self: MetricPrefix,
        __value: ComplexT,
        /,
        to: MetricPrefix = NONE,  # type: ignore[assignment]
    ) -> ComplexT:
        ...

    def convert(
        self,
        __value,
        /,
        to=NONE,
    ):
        """Convert value from metric prefix self to to."""
        if self is to:
            return __value

        return __value * self.to(to, number_type=type(__value))

    @staticmethod
    @functools.cache
    def _symbols() -> types.MappingProxyType[MetricPrefix, str]:
        return types.MappingProxyType(
            {
                MetricPrefix.quetta: "Q",
                MetricPrefix.ronna: "R",
                MetricPrefix.yotta: "Y",
                MetricPrefix.zetta: "Z",
                MetricPrefix.exa: "E",
                MetricPrefix.peta: "P",
                MetricPrefix.tera: "T",
                MetricPrefix.giga: "G",
                MetricPrefix.mega: "M",
                MetricPrefix.kilo: "k",
                MetricPrefix.hecto: "h",
                MetricPrefix.deca: "da",
                MetricPrefix.NONE: "",
                MetricPrefix.deci: "d",
                MetricPrefix.centi: "c",
                MetricPrefix.milli: "m",
                MetricPrefix.micro: "μ",
                MetricPrefix.nano: "n",
                MetricPrefix.pico: "p",
                MetricPrefix.femto: "f",
                MetricPrefix.atto: "a",
                MetricPrefix.zepto: "z",
                MetricPrefix.yocto: "y",
                MetricPrefix.ronto: "r",
                MetricPrefix.quecto: "q",
            },
        )

    @classmethod
    @functools.cache
    def _by_symbol(
        cls: type[MetricPrefix],
    ) -> types.MappingProxyType[str, MetricPrefix]:
        return types.MappingProxyType(
            {symbol: metric_prefix for metric_prefix, symbol in cls._symbols().items()},
        )

Ancestors

• enum.IntEnum
• builtins.int
• enum.Enum

Class variables

var NONE

var atto

var centi

var deca

var deci

var exa

var femto

var giga

var hecto

var kilo

var mega

var micro

var milli

var nano

var peta

var pico

var quecto

var quetta

var ronna

var ronto

var tera

var yocto

var yotta

var zepto

var zetta

Static methods

def from_symbol(symbol: str, /) ‑> MetricPrefix

Return MetricPrefix by symbol.

Expand source code

@classmethod
def from_symbol(cls: type[MetricPrefix], symbol: str, /) -> MetricPrefix:
    """Return MetricPrefix by symbol."""
    return cls._by_symbol()[symbol]

Instance variables

var symbol

Metric prefix symbol, e.g. G for giga.

Expand source code

def __get__(self, instance, owner=None):
    if instance is None:
        return self
    if self.attrname is None:
        raise TypeError(
            "Cannot use cached_property instance without calling __set_name__ on it.")
    try:
        cache = instance.__dict__
    except AttributeError:  # not all objects have __dict__ (e.g. class defines slots)
        msg = (
            f"No '__dict__' attribute on {type(instance).__name__!r} "
            f"instance to cache {self.attrname!r} property."
        )
        raise TypeError(msg) from None
    val = cache.get(self.attrname, _NOT_FOUND)
    if val is _NOT_FOUND:
        with self.lock:
            # check if another thread filled cache while we awaited lock
            val = cache.get(self.attrname, _NOT_FOUND)
            if val is _NOT_FOUND:
                val = self.func(instance)
                try:
                    cache[self.attrname] = val
                except TypeError:
                    msg = (
                        f"The '__dict__' attribute on {type(instance).__name__!r} instance "
                        f"does not support item assignment for caching {self.attrname!r} property."
                    )
                    raise TypeError(msg) from None
    return val

Methods

def convert(self, _MetricPrefix__value, /, to=0)

Convert value from metric prefix self to to.

Expand source code

def convert(
    self,
    __value,
    /,
    to=NONE,
):
    """Convert value from metric prefix self to to."""
    if self is to:
        return __value

    return __value * self.to(to, number_type=type(__value))

def to(self: MetricPrefix, _MetricPrefix__other: MetricPrefix | int, /, *, number_type: type[int | ComplexT] = builtins.int) ‑> int | ComplexT

Calculate conversion factor between self and other.

Expand source code

def to(
    self: MetricPrefix,
    __other: MetricPrefix | int,
    /,
    *,
    number_type: type[int | ComplexT] = int,
) -> int | ComplexT:
    """Calculate conversion factor between self and other."""
    return number_type(_BASE) ** (self - __other)