Simple Unit (Python implementation)

• Standard usage
• Operator overloading usage
• Documentation

This package is the Python Reference Implementation (RI) of the Simple Unit specification. Nevertheless, it also contains some extensions to the specification standard.

Standard usage

The standard usage refers to methods and classes defined in the Simple Unit specification.

Usage of transformed units:

import unit_simple as su

m = su.FundamentalUnit()
km = m.scale_multiply(1000)
cm = m.scale_divide(100)
cmToKm = cm.get_converter_to(km)

cmToKm.convert(3) # 0.00003
cmToKm.inverse().convert(0.00003) # 3

Usage of derived units:

import unit_simple as su

m = su.FundamentalUnit()
km = m.scale_multiply(1000)

km2 = su.DerivedUnit(km.factor(2))
cm = m.scale_divide(100)
cm2 = su.DerivedUnit(cm.factor(2))
km2Tocm2 = km2.get_converter_to(cm2)

km2Tocm2.convert(3) # 30000000000
km2Tocm2.inverse().convert(30000000000) # 3

Usage of derived units combining dimensions:

import unit_simple as su

m = su.FundamentalUnit()
kg = su.FundamentalUnit()
g = kg.scale_divide(1000)
ton = kg.scale_multiply(1000)
gPerM2 = su.DerivedUnit(g, m.factor(-2))
km = m.scale_multiply(1000)
tonPerKm2 = su.DerivedUnit(ton, km.factor(-2))
cm = m.scale_divide(100)
tonPerCm2 = su.DerivedUnit(ton, cm.factor(-2))
gPerM2ToTonPerKm2 = gPerM2.get_converter_to(tonPerKm2)
gPerM2ToTonPerCm2 = gPerM2.get_converter_to(tonPerCm2)

gPerM2ToTonPerKm2.convert(1) # 1
gPerM2ToTonPerKm2.inverse().convert(3) # 3
gPerM2ToTonPerCm2.convert(1) # 1e-4
gPerM2ToTonPerCm2.convert(3) # 3e-10
gPerM2ToTonPerCm2.offset() # 0.0
gPerM2ToTonPerCm2.scale() # 1e-10
gPerM2ToTonPerCm2.inverse().offset() # -0.0
gPerM2ToTonPerCm2.inverse().convert(3e-10) # 3

Usage of temperatures (affine and linear conversions):

import unit_simple as su

k = su.FundamentalUnit()
c = k.shift(273.15)
kToC = k.get_converter_to(c)

kToC.convert(0) # -273.15
kToC.inverse().convert(0) # 273.15

# combined with other units, temperatures only keep their linear conversion part
m = su.FundamentalUnit()
cPerM = su.DerivedUnit(c, m.factor(-1))
kPerM = su.DerivedUnit(k, m.factor(-1))
kPerMToCPerM = kPerM.get_converter_to(cPerM)

kPerMToCPerM.convert(3) # 3
kPerMToCPerM.inverse().convert(3) # 3

Usage of non-decimal conversions:

import unit_simple as su

m = su.FundamentalUnit()
km = m.scale_multiply(1000.)

s = su.FundamentalUnit()
h = s.scale_multiply(3600.)

ms = su.DerivedUnit(m, s.factor(-1))
kmh = su.DerivedUnit(km, h.factor(-1))

msToKmh = ms.get_converter_to(kmh)

msToKmh.convert(100.) # 360
msToKmh.inverse().convert(18.) # 5

Operator overloading usage

The Simple Unit Python implementation provides an extension of the base specification to overloads some language operators.

Usage of transformed units:

import unit_simple as su

m = su.FundamentalUnit()
km = m * 1000
cm = m / 100
cmToKm = cm >> km

cmToKm(3) # 0.00003
(~cmToKm)(0.00003) # 3

Usage of derived Units:

import unit_simple as su

m = su.FundamentalUnit()
km = m * 1000

km2 = km ** 2
cm = m / 100
cm2 = cm ** 2
km2Tocm2 = km2 >> cm2

km2Tocm2(3) # 30000000000
(~km2Tocm2)(30000000000) # 3

Usage of derived units combining dimensions:

import unit_simple as su

m = su.FundamentalUnit()
kg = su.FundamentalUnit()
g = kg / 1000
ton = kg * 1000
gPerM2 = g / m ** 2
km = m * 1000
tonPerKm2 = ton * ~km ** 2
cm = m / 100
tonPerCm2 = ton / cm ** 2
gPerM2ToTonPerKm2 = gPerM2 >> tonPerKm2
gPerM2ToTonPerCm2 = tonPerCm2 << gPerM2

gPerM2ToTonPerKm2(1) # 1
(~gPerM2ToTonPerKm2)(3) # 3
gPerM2ToTonPerCm2(1) # 1e-10
gPerM2ToTonPerCm2(3) # 3e-10
gPerM2ToTonPerCm2.offset() # 0.0
gPerM2ToTonPerCm2.scale() # 1e-10
(~gPerM2ToTonPerCm2).offset() # -0.0
(~gPerM2ToTonPerCm2)(3e-10) # 3

Usage of temperatures (affine and linear conversions):

import unit_simple as su

k = su.FundamentalUnit()
c = k + 273.15
kToC = k >> c

kToC(0) # -273.15
(~kToC)(0) # 273.15

# combined with other units, temperatures only keep their linear conversion part
m = su.FundamentalUnit()
cPerM = c / m
kPerM = k / m
kPerMToCPerM = kPerM >> cPerM

kPerMToCPerM(3) # 3
(~kPerMToCPerM)(3) # 3

Usage of non-decimal conversions:

import unit_simple as su

m = su.FundamentalUnit()
km = m * 1000.

s = su.FundamentalUnit()
h = s * 3600.

ms = m / s
kmh = km / h

msToKmh = ms >> kmh

msToKmh(100.) # 360
(~msToKmh)(18.) # 5

Documentation

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