siquant 3.0.5

SI units and quantities library

siquant is a simple pure python 3 library to make dimensional analysis painless.

Getting Started

Dimensional Analysis

>>> from siquant.systems import si
>>> force = 100 * si.kilonewtons
>>> moment_arm = 50 * si.meters
>>> torque = force * moment_arm
>>> torque.quantity
5000
>>> str(torque.units)
'1000*kg**1*m**2*s**-2'
>>> torque.get_as(si.newtons * si.meters)
5000000.0
>>> torque.get_as(si.newtons)
Traceback (most recent call last):
  ...
siquant.exceptions.UnitMismatchError: ...

>>> torque = torque.cvt_to(si.newtons * si.meters)
>>> torque.quantity
5000000.0
>>> str(torque.units)
'1*kg**1*m**2*s**-2'

Validation

>>> from siquant.dimensions import force, area, stress
>>> from siquant.systems import si

>>> def normal_stress(force_q, area_q):
...     assert force_q.is_of(force)
...     assert area_q.is_of(area)
...     return force_q / area_q

>>> stress_q = normal_stress(1 * si.newtons, 1 * si.meters ** 2)
>>> stress_q.is_of(stress)
True
>>> stress_q.is_of(area)
False

Sometimes you might want to check for dimensions that aren’t provided by default.

>>> from siquant.dimensions import SIDimensions
>>> from siquant.systems import si

>>> new_dim = SIDimensions(kg=1, m=1, s=1, k=1, a=1, mol=1, cd=1)
>>> dist_q = 1 * si.meters
>>> dist_q.is_of(new_dim)
False

Normalization

>>> from siquant import ScalarQuantity
>>> from siquant.systems import si

>>> meters_cvt = ScalarQuantity.As(si.meters)

>>> dist_q = meters_cvt(1000 * si.millimeters)
>>> dist_q.quantity
1

>>> dist_q = meters_cvt(1000 * si.meters)
>>> dist_q.quantity
1000

>>> dist_q = meters_cvt(1000)
>>> dist_q.quantity
1000

New Units

SIUnit can be created directly by factory:

>>> from siquant.units import SIUnit
>>> fathom = SIUnit.Unit(1.8288, m=1)
SIUnit(1.8288, (0, 1, 0, 0, 0, 0, 0))

Alternatively they can be derived:

>>> from siquant.systems import si
>>> rpm = si.unity / si.minutes
>>> rpm
SIUnit(0.016667, (0, 0, -1, 0, 0, 0, 0))