>>> from unit_aware import Units, UnitAwareValue, UnitsVector
>>> UnitAwareValue(120, Units.velocity) * UnitAwareValue(60, Units.time)
UnitAwareValue(value=7200, units=UnitsVector(time=0, length=1, mass=0, current=0, temperature=0, luminous_intensity=0, amount_of_substance=0))UnitsVector holds info about units of measurement as a 7 dimensional vector
Units contains shortcuts to these based on what you are measuring.
You can use this to check that the units you are using make sense
>>> Units.area # SI: m^2
UnitsVector(time=0, length=2, mass=0, current=0, temperature=0, luminous_intensity=0, amount_of_substance=0)
>>> Units.acceleration # SI: m/s^2
UnitsVector(time=-2, length=1, mass=0, current=0, temperature=0, luminous_intensity=0, amount_of_substance=0)UnitAwareValue prevents addition and subtraction with mismatched units, the below raises informing you of the mismatch
>>> UnitAwareValue(120, Units.area) + UnitAwareValue(120, Units.volume)SIUnitAwareValue has a repr which displays the SI units, including basic support for derived units.
from unit_aware import Units, SIUnitAwareValue as SIV
>>> SIV(1, Units.scalar_value) / SIV(1, Units.time)
1.0 Hz
>>> SIV(1, Units.velocity) * SIV(1, Units.time)
1 m
>>> SIV(1, Units.velocity) + SIV(1, Units.acceleration) * SIV(1, Units.time)
2 m/s
>>> SIV(1, Units.power) / SIV(1, Units.current)
1.0 VIf it can't determine an equivalent derived unit appears to make sense:
>>> SIV(1, Units.power) / SIV(1, Units.time) * SIV(1, Units.area) / SIV(1, Units.time)
1.0 m⁴kg/s⁵Not all SI recognized derived units are supported for automatic display.
- Radians, and steradians are dimensionless. You can insert them as appropriate without other modification to what is displayed.
- Celcius is not supported by this at this time. This may not change (needs consideration of impact)
- gray and sievert are excluded, having the same dimensionality with slightly differing semantic meaning.
- May add as sievert, with the expectation that those who need gray know the dimensional equivalence
- becquerel is excluded for dimensional equivalence to hertz, with hertz being significantly more common
UnitAwareValue and SIUnitAwareValue both accept any type which support additon, subtraction, multiplcation, division, and equality comparison for a value.
You can use the builtin fractions.Fraction or decimal.Decimal if specific precision is required
>>> from fractions import Fraction
>>> from unit_aware import Units, SIUnitAwareValue as SIV
>>> SIV(Fraction("5/4"), Units.length) / SIV(Fraction("3"), Units.time)
5/12 m/sWhile the base units here correspond to the SI base units, nothing here prevents using these with any coherent system of measurement
consider, the 7 Cs A system of measurement based around
- Velocity (the speed of light)
- Energy (calorie)
- Frequency (middle c)
- Temperature (degrees celcius)
- Luminous Intensity (candela)
- Charge (coulomb)
- Amount of Substance (100, roman numeral C)
In this system of measurement, derived units still work just fine
Current is measured in "middle C coulombs", which to anyone used to working in more standard units is absurd.
but units vectors don't care about the units, only the coherence of the units, so
>>> midc_coulomb = UnitAwareValue(1, Units.frequency) * UnitAwareValue(1, Units.charge)
>>> midc_coulomb.units == Units.current
TrueThis doesn't mean the values are equivalent to those of the SI, you still need to scale based on the base units in this case, scaling by a factor of 220 * (2**(1/4)), as charge is the same in both systems, and the seven cs uses middle C (c4), assuming A4 is 440hz and 12-tone equal temperament
- Parsing from string for SI units.
- Conversion matrices for other coherent systems.
- Display in terms of equivalent specified units with error on units not being compatible
- Possible extended form for units that allows defining in terms of relation to SI for non-coherent units?