Units (astronat.units)

Reference/API

astronat.units Package

Astropy Units. Extended.

provides full drop-in replacement for astropy units.

Functions

quantity_return_(res[, unit, to_value, …])	Control function return of Quantity.
from_amuse(quantity)	Convert AMUSE quantity to astropy quantity.
hms_str_to_unit(hms[, empty_to_, copy])	Change a hms string to Astropy deg units.
quantity_io([function, unit, to_value, …])	Decorator for validating the units of arguments to functions.

Classes

QuantityInputOutput(function, unit, …)

Decorator for validating the units of arguments to functions.

Class Inheritance Diagram

astronat.units.composite Module

Composite Astropy units.

Available Units

Unit	Description	Represents	Aliases	SI Prefixes
km_s	kilometer per second composite unit	\(\mathrm{\frac{km}{s}}\)	kmps	No
km_skpc	kilometer per second per kiloparsec composite unit	\(\mathrm{\frac{km}{kpc\,s}}\)	kmpspkpc	No
km_sMpc	kilometer per second per Megaparsec composite unit	\(\mathrm{\frac{km}{Mpc\,s}}\)	kmpspMpc, hubble, Hubble	No
m_s	meter per second composite unit	\(\mathrm{\frac{m}{s}}\)	mps	No
mas_yr	milli-arcseconds / year composite unit	\(\mathrm{\frac{mas}{yr}}\)	maspyr	No

astronat.units.amuse Module

Astropy units, extended for AMUSE compatibility.

These units are also available in the units namespace.

Not all AMUSE units are compatible with Astropy since some unit names are already present in Astropy. These units are:

• ms (meters per second), which in Astropy means milliseconds

• myr (million years), which in Astropy means milliyear

This module prioritizes Astropy compatibility, so uses the Astropy versions. For full AMUSE definitions in astropy units, the full_amuse should be used.

Available Units

Unit	Description	Represents	Aliases	SI Prefixes
A	ampere: base unit of electric current in SI		ampere, amp	No
amu	atomic mass unit, AMUSE compatibility	\(\mathrm{u}\)		No
arcmin	arc minute: angular measurement	\(\mathrm{0.016666667\,{}^{\circ}}\)	arcminute	No
arcsec	arc second: angular measurement	\(\mathrm{0.00027777778\,{}^{\circ}}\)	arcsecond	No
AU	astronomical unit: approximately the mean Earth–Sun distance.	\(\mathrm{1.4959787 \times 10^{11}\,m}\)	au, astronomical_unit	No
AUd	AU per day, AMUSE compatibility	\(\mathrm{1.4959787 \times 10^{11}\,\frac{m}{d}}\)		No
C	coulomb: electric charge	\(\mathrm{A\,s}\)	coulomb	No
cd	candela: base unit of luminous intensity in SI		candela	No
cm	centimeter (cm)	\(\mathrm{cm}\)	centimeter	No
deg	degree: angular measurement 1/360 of full rotation	\(\mathrm{0.017453293\,rad}\)	degree	No
e	electron charge, AMUSE compatibility	\(\mathrm{1.6021766 \times 10^{-19}\,C}\)		No
E_h	Hartree energy, AMUSE compatibility	\(\mathrm{2\,R_{\infty}}\)	Hartree_energy	No
erg	erg: CGS unit of energy	\(\mathrm{\frac{cm^{2}\,g}{s^{2}}}\)		No
eV	Electron Volt	\(\mathrm{1.6021766 \times 10^{-19}\,J}\)	electronvolt	Yes
F	Farad: electrical capacitance	\(\mathrm{\frac{C}{V}}\)	Farad, farad	No
g	gram (g)	\(\mathrm{0.001\,kg}\)	gram	No
gyr	billion years, AMUSE compatibility.	\(\mathrm{Gyr}\)		No
Hz	Frequency	\(\mathrm{\frac{1}{s}}\)	Hertz, hertz	Yes
J	Joule: energy	\(\mathrm{N\,m}\)	Joule, joule	No
julianyr	julian year, AMUSE compatibility	\(\mathrm{365.25\,d}\)		No
K	Kelvin: temperature with a null point at absolute zero.		Kelvin	No
kelvin	Kelvin, AMUSE compatibility	\(\mathrm{K}\)		No
kg	kilogram: base unit of mass in SI.		kilogram	No
kms	kilometer per seconds, AMUSE compatibility	\(\mathrm{\frac{km}{s}}\)		No
LSun	solar luminosity, AMUSE compatibility	\(\mathrm{L_{\odot}}\)		No
ly	light year, AMUSE compatibility	\(\mathrm{lyr}\)		No
m	meter: base unit of length in SI		meter	No
MEarth	Jupiter mass, AMUSE compatibility	\(\mathrm{M_{\oplus}}\)		No
metallicity	metallicity: base unit of metallicity in AMUSE			Yes
MJupiter	Jupiter mass, AMUSE compatibility	\(\mathrm{M_{\rm J}}\)		No
mol	mole: amount of a chemical substance in SI.		mole	No
MSun	solar mass, AMUSE compatibility	\(\mathrm{M_{\odot}}\)		No
N	Newton: force	\(\mathrm{\frac{kg\,m}{s^{2}}}\)	Newton, newton	No
object_key	object_key: base particle key unit in AMUSE			Yes
Pa	Pascal: pressure	\(\mathrm{\frac{J}{m^{3}}}\)	Pascal, pascal	No
pc	parsec: approximately 3.26 light-years.	\(\mathrm{3.0856776 \times 10^{16}\,m}\)	parsec	Yes
%	percent: one hundredth of unity, factor 0.01	\(\mathrm{0.01\,}\)	pct	No
pi	pi radians, AMUSE compatibility	\(\mathrm{3.1415927\,rad}\)		No
rad	radian: angular measurement of the ratio between the length on an arc and its radius		radian	No
REarth	Jupiter radius, AMUSE compatibility	\(\mathrm{R_{\oplus}}\)		No
rev	revolutions, AMUSE compatibility	\(\mathrm{6.2831853\,rad}\)		No
RJupiter	Jupiter radius, AMUSE compatibility	\(\mathrm{R_{\rm J}}\)		No
RSun	solar radius, AMUSE compatibility	\(\mathrm{R_{\odot}}\)		No
Ry	Rydberg: Energy of a photon whose wavenumber is the Rydberg constant	\(\mathrm{13.605693\,eV}\)	rydberg	No
s	second: base unit of time in SI.		second	No
S	Siemens: electrical conductance	\(\mathrm{\frac{A}{V}}\)	Siemens, siemens	No
sr	steradian: unit of solid angle in SI	\(\mathrm{rad^{2}}\)	steradian	No
stellar_type	stellar_type: base stellar type unit in AMUSE			Yes
string	string: base string unit in AMUSE			Yes
T	Tesla: magnetic flux density	\(\mathrm{\frac{Wb}{m^{2}}}\)	Tesla, tesla	No
V	Volt: electric potential or electromotive force	\(\mathrm{\frac{J}{C}}\)	Volt, volt	No
W	Watt: power	\(\mathrm{\frac{J}{s}}\)	Watt, watt	No
Wb	Weber: magnetic flux	\(\mathrm{V\,s}\)	Weber, weber	No
yr	year (yr)	\(\mathrm{365.25\,d}\)	year	Yes

astropy.units Package

This subpackage contains classes and functions for defining and converting between different physical units.

This code is adapted from the pynbody units module written by Andrew Pontzen, who has granted the Astropy project permission to use the code under a BSD license.

Functions

add_enabled_equivalencies(equivalencies)	Adds to the equivalencies enabled in the unit registry.
add_enabled_units(units)	Adds to the set of units enabled in the unit registry.
allclose(a, b[, rtol, atol, equal_nan])	Whether two arrays are element-wise equal within a tolerance.
beam_angular_area(beam_area)	Convert between the beam unit, which is commonly used to express the area of a radio telescope resolution element, and an area on the sky.
brightness_temperature(frequency[, beam_area])	Defines the conversion between Jy/sr and “brightness temperature”, \(T_B\), in Kelvins.
def_physical_type(unit, name)	Adds a new physical unit mapping.
def_unit(s[, represents, doc, format, …])	Factory function for defining new units.
dimensionless_angles()	Allow angles to be equivalent to dimensionless (with 1 rad = 1 m/m = 1).
doppler_optical(rest)	Return the equivalency pairs for the optical convention for velocity.
doppler_radio(rest)	Return the equivalency pairs for the radio convention for velocity.
doppler_relativistic(rest)	Return the equivalency pairs for the relativistic convention for velocity.
get_current_unit_registry()
get_physical_type(unit)	Given a unit, returns the name of the physical quantity it represents.
isclose(a, b[, rtol, atol, equal_nan])	Return a boolean array where two arrays are element-wise equal within a tolerance.
logarithmic()	Allow logarithmic units to be converted to dimensionless fractions
mass_energy()	Returns a list of equivalence pairs that handle the conversion between mass and energy.
molar_mass_amu()	Returns the equivalence between amu and molar mass.
parallax()	Returns a list of equivalence pairs that handle the conversion between parallax angle and distance.
pixel_scale(pixscale)	Convert between pixel distances (in units of pix) and other units, given a particular pixscale.
plate_scale(platescale)	Convert between lengths (to be interpreted as lengths in the focal plane) and angular units with a specified platescale.
quantity_input([func])	A decorator for validating the units of arguments to functions.
set_enabled_equivalencies(equivalencies)	Sets the equivalencies enabled in the unit registry.
set_enabled_units(units)	Sets the units enabled in the unit registry.
spectral()	Returns a list of equivalence pairs that handle spectral wavelength, wave number, frequency, and energy equivalences.
spectral_density(wav[, factor])	Returns a list of equivalence pairs that handle spectral density with regard to wavelength and frequency.
temperature()	Convert between Kelvin, Celsius, Rankine and Fahrenheit here because Unit and CompositeUnit cannot do addition or subtraction properly.
temperature_energy()	Convert between Kelvin and keV(eV) to an equivalent amount.
thermodynamic_temperature(frequency[, T_cmb])	Defines the conversion between Jy/sr and “thermodynamic temperature”, \(T_{CMB}\), in Kelvins.
with_H0([H0])	Convert between quantities with little-h and the equivalent physical units.
zero_point_flux(flux0)	An equivalency for converting linear flux units (“maggys”) defined relative to a standard source into a standardized system.

Classes

CompositeUnit(scale, bases, powers[, …])	Create a composite unit using expressions of previously defined units.
Decibel(value[, unit, dtype, copy, order, …])
DecibelUnit([physical_unit, function_unit])	Logarithmic physical units expressed in dB
Dex(value[, unit, dtype, copy, order, …])
DexUnit([physical_unit, function_unit])	Logarithmic physical units expressed in magnitudes
FunctionQuantity(value[, unit, dtype, copy, …])	A representation of a (scaled) function of a number with a unit.
FunctionUnitBase([physical_unit, function_unit])	Abstract base class for function units.
IrreducibleUnit(st[, doc, format, namespace])	Irreducible units are the units that all other units are defined in terms of.
LogQuantity(value[, unit, dtype, copy, …])	A representation of a (scaled) logarithm of a number with a unit
LogUnit([physical_unit, function_unit])	Logarithmic unit containing a physical one
MagUnit([physical_unit, function_unit])	Logarithmic physical units expressed in magnitudes
Magnitude(value[, unit, dtype, copy, order, …])
NamedUnit(st[, doc, format, namespace])	The base class of units that have a name.
PrefixUnit(s[, represents, format, …])	A unit that is simply a SI-prefixed version of another unit.
Quantity(value[, unit, dtype, copy, order, …])	A Quantity represents a number with some associated unit.
QuantityInfo([bound])	Container for meta information like name, description, format.
QuantityInfoBase([bound])
SpecificTypeQuantity(value[, unit, dtype, …])	Superclass for Quantities of specific physical type.
Unit(s[, represents, format, namespace, …])	The main unit class.
UnitBase()	Abstract base class for units.
UnitConversionError	Used specifically for errors related to converting between units or interpreting units in terms of other units.
UnitTypeError	Used specifically for errors in setting to units not allowed by a class.
UnitsError	The base class for unit-specific exceptions.
UnitsWarning	The base class for unit-specific warnings.
UnrecognizedUnit(st[, doc, format, namespace])	A unit that did not parse correctly.

Class Inheritance Diagram