unyt.unit_systems module

Unit system class.

unyt.unit_systems.add_symbols(namespace, registry)[source]

Adds the unit symbols from unyt.unit_symbols to a namespace

Parameters:

  • namespace (dict) – The dict to insert unit symbols into. The keys will be string unit names and values will be the corresponding unit objects.

  • registry (unyt.unit_registry.UnitRegistry) – The registry to create units from. Note that if you would like to use a custom unit system, ensure your registry was created using that unit system.

Example

>>> from unyt.unit_registry import UnitRegistry
>>> class MyClass():
...     def __init__(self):
...         self.reg = UnitRegistry()
...         add_symbols(vars(self), self.reg)
>>> foo = MyClass()
>>> foo.kilometer
km
>>> foo.joule
J
unyt.unit_systems.add_constants(namespace, registry)[source]

Adds the quantities from unyt.physical_constants to a namespace

Parameters:

  • namespace (dict) – The dict to insert quantities into. The keys will be string names and values will be the corresponding quantities.

  • registry (unyt.unit_registry.UnitRegistry) – The registry to create units from. Note that if you would like to use a custom unit system, ensure your registry was created using that unit system.

Example

>>> from unyt.unit_registry import UnitRegistry
>>> class MyClass():
...     def __init__(self):
...         self.reg = UnitRegistry(unit_system='cgs')
...         add_constants(vars(self), self.reg)
>>> foo = MyClass()
>>> foo.gravitational_constant
unyt_quantity(6.67408e-08, 'cm**3/(g*s**2)')
>>> foo.speed_of_light
unyt_quantity(2.99792458e+10, 'cm/s')
class unyt.unit_systems.UnitSystem(name, length_unit, mass_unit, time_unit, temperature_unit='K', angle_unit='rad', current_mks_unit='A', luminous_intensity_unit='cd', logarithmic_unit='Np', registry=None)[source]

Bases: object

Create a UnitSystem for facilitating conversions to a default set of units.

Parameters:

  • name (string) – The name of the unit system. Will be used as the key in the unit_system_registry dict to reference the unit system by.

  • length_unit (string or unyt.unit_object.Unit) – The base length unit of this unit system.

  • mass_unit (string or unyt.unit_object.Unit) – The base mass unit of this unit system.

  • time_unit (string or unyt.unit_object.Unit) – The base time unit of this unit system.

  • temperature_unit (string or unyt.unit_object.Unit, optional) – The base temperature unit of this unit system. Defaults to “K”.

  • angle_unit (string or unyt.unit_object.Unit, optional) – The base angle unit of this unit system. Defaults to “rad”.

  • mks_system (boolean, optional) – Whether or not this unit system has SI-specific units. Default: False

  • current_mks_unit (string or unyt.unit_object.Unit, optional) – The base current unit of this unit system. Defaults to “A”.

  • luminous_intensity_unit (string or unyt.unit_object.Unit, optional) – The base luminous intensity unit of this unit system. Defaults to “cd”.

  • registry (unyt.unit_registry.UnitRegistry object) – The unit registry associated with this unit system. Only useful for defining unit systems based on code units.

property has_current_mks

Does this unit system have an MKS current dimension?

unyt.unit_systems.cgs_unit_system = cgs Unit System  Base Units:   length: cm   mass: g   time: s   temperature: K   angle: rad   luminous_intensity: cd   logarithmic: Np  Other Units:   energy: erg   specific_energy: erg/g   pressure: dyn/cm**2   force: dyn   magnetic_field_cgs: G   charge_cgs: statC   current_cgs: statA   power: erg/s

The CGS unit system

unyt.unit_systems.mks_unit_system = mks Unit System  Base Units:   length: m   mass: kg   time: s   temperature: K   angle: rad   current_mks: A   luminous_intensity: cd   logarithmic: Np  Other Units:   energy: J   specific_energy: J/kg   pressure: Pa   force: N   magnetic_field: T   charge: C   frequency: Hz   power: W   electric_potential: V   capacitance: F   inductance: H   resistance: Ω   magnetic_flux: Wb   luminous_flux: lm

The MKS unit system

unyt.unit_systems.imperial_unit_system = imperial Unit System  Base Units:   length: ft   mass: lb   time: s   temperature: R   angle: rad   current_mks: A   luminous_intensity: cd   logarithmic: Np  Other Units:   force: lbf   energy: ft*lbf   pressure: lbf/ft**2   power: hp

The imperial unit system

unyt.unit_systems.galactic_unit_system = galactic Unit System  Base Units:   length: kpc   mass: Msun   time: Myr   temperature: K   angle: rad   current_mks: A   luminous_intensity: cd   logarithmic: Np  Other Units:   energy: keV   magnetic_field_cgs: μG

The galactic unit system

unyt.unit_systems.solar_unit_system = solar Unit System  Base Units:   length: AU   mass: Mearth   time: yr   temperature: K   angle: rad   current_mks: A   luminous_intensity: cd   logarithmic: Np  Other Units:

The solar unit system

unyt.unit_systems.geometrized_unit_system = geometrized Unit System  Base Units:   length: l_geom   mass: m_geom   time: t_geom   temperature: K   angle: rad   current_mks: A   luminous_intensity: cd   logarithmic: Np  Other Units:

Geometrized unit system

unyt.unit_systems.planck_unit_system = planck Unit System  Base Units:   length: l_pl   mass: m_pl   time: t_pl   temperature: T_pl   angle: rad   current_mks: A   luminous_intensity: cd   logarithmic: Np  Other Units:   energy: E_pl   charge_mks: q_pl

Planck unit system