Some utilities for work with units of physical quantities.
A physical quantity in a given set of basic units.
Examples
Construct the stress quantity:
>>> from sfepy.mechanics.units import Unit, Quantity
>>> units = ['m', 's', 'kg', 'C']
>>> unit_set = [Unit(key) for key in units]
>>> q1 = Quantity('stress', unit_set)
>>> q1()
'1.0 Pa'
Show its unit using various prefixes:
>>> q1('m')
'1000.0 mPa'
>>> q1('')
'1.0 Pa'
>>> q1('k')
'0.001 kPa'
>>> q1('M')
'1e-06 MPa'
Construct the stress quantity in another unit set:
>>> units = ['mm', 's', 'kg', 'C']
>>> unit_set = [Unit(key) for key in units]
>>> q2 = Quantity('stress', unit_set)
>>> q2()
'1.0 kPa'
Show its unit using various prefixes:
>>> q2('m')
'1000000.0 mPa'
>>> q2('')
'1000.0 Pa'
>>> q2('k')
'1.0 kPa'
>>> q2('M')
'0.001 MPa'
A unit of a physical quantity. The prefix and coefficient of the unit are determined from to its name.
Examples
Construct some units:
>>> from sfepy.mechanics.units import Unit
>>> unit = Unit('mm')
>>> print unit
Unit:mm
coef:
0.001
name:
mm
prefix:
m
prefix_length:
1
unit:
m
>>> unit = Unit('kg')
>>> print unit
Unit:kg
coef:
1000.0
name:
kg
prefix:
k
prefix_length:
1
unit:
g
Get prefixes for a coefficient:
>>> Unit.get_prefix(100.0)
('d', 10.0)
>>> Unit.get_prefix(100.0, omit=('d',))
('k', 0.10000000000000001)