prefix_conversions_string.py

"""
* Author: Manuel Di Lullo (https://github.com/manueldilullo)
* Description: Convert a number to use the correct SI or Binary unit prefix.

Inspired by prefix_conversion.py file in this repository by lance-pyles

URL: https://en.wikipedia.org/wiki/Metric_prefix#List_of_SI_prefixes
URL: https://en.wikipedia.org/wiki/Binary_prefix
"""

from __future__ importannotations

fromenumimportEnum, unique
fromtypingimportTypeVar

# Create a generic variable that can be 'Enum', or any subclass.
T=TypeVar("T", bound="Enum")


@unique
classBinaryUnit(Enum):
yotta=80
zetta=70
exa=60
peta=50
tera=40
giga=30
mega=20
kilo=10


@unique
classSIUnit(Enum):
yotta=24
zetta=21
exa=18
peta=15
tera=12
giga=9
mega=6
kilo=3
hecto=2
deca=1
deci=-1
centi=-2
milli=-3
micro=-6
nano=-9
pico=-12
femto=-15
atto=-18
zepto=-21
yocto=-24

@classmethod
defget_positive(cls) ->dict:
"""
 Returns a dictionary with only the elements of this enum
 that has a positive value
 >>> from itertools import islice
 >>> positive = SIUnit.get_positive()
 >>> inc = iter(positive.items())
 >>> dict(islice(inc, len(positive) // 2))
 {'yotta': 24, 'zetta': 21, 'exa': 18, 'peta': 15, 'tera': 12}
 >>> dict(inc)
 {'giga': 9, 'mega': 6, 'kilo': 3, 'hecto': 2, 'deca': 1}
 """
return {unit.name: unit.valueforunitinclsifunit.value>0}

@classmethod
defget_negative(cls) ->dict:
"""
 Returns a dictionary with only the elements of this enum
 that has a negative value
 @example
 >>> from itertools import islice
 >>> negative = SIUnit.get_negative()
 >>> inc = iter(negative.items())
 >>> dict(islice(inc, len(negative) // 2))
 {'deci': -1, 'centi': -2, 'milli': -3, 'micro': -6, 'nano': -9}
 >>> dict(inc)
 {'pico': -12, 'femto': -15, 'atto': -18, 'zepto': -21, 'yocto': -24}
 """
return {unit.name: unit.valueforunitinclsifunit.value<0}


defadd_si_prefix(value: float) ->str:
"""
 Function that converts a number to his version with SI prefix
 @input value (an integer)
 @example:
 >>> add_si_prefix(10000)
 '10.0 kilo'
 """
prefixes=SIUnit.get_positive() ifvalue>0elseSIUnit.get_negative()
forname_prefix, value_prefixinprefixes.items():
numerical_part=value/ (10**value_prefix)
ifnumerical_part>1:
returnf"{numerical_part!s}{name_prefix}"
returnstr(value)


defadd_binary_prefix(value: float) ->str:
"""
 Function that converts a number to his version with Binary prefix
 @input value (an integer)
 @example:
 >>> add_binary_prefix(65536)
 '64.0 kilo'
 """
forprefixinBinaryUnit:
numerical_part=value/ (2**prefix.value)
ifnumerical_part>1:
returnf"{numerical_part!s}{prefix.name}"
returnstr(value)


if__name__=="__main__":
importdoctest

doctest.testmod()