135 lines
4.2 KiB
Python
135 lines
4.2 KiB
Python
"""Access `scipy.constants` using `sympy` units.
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Notes:
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See <https://docs.scipy.org/doc/scipy/reference/constants.html#scipy.constants.physical_constants>
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Attributes:
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_SCIPY_COMBINED_UNITS: A mapping from scipy constant names to its combined unit, represented as a tuple of "base" units.
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SCIPY_UNIT_TO_SYMPY_UNIT: A mapping from scipy constant names to its combined unit, represented as a tuple of "base" units.
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SCI_CONSTANTS: A mapping from scipy constant names to an equivalent sympy expression.expression.
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SCI_CONSTANTS_REF: Original source of constant data / choices.
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"""
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import functools
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import scipy as sc
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import sympy as sp
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import sympy.physics.units as spu
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from . import extra_sympy_units as spux
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SUPPORTED_SCIPY_PREFIX = '1.12'
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if not sc.version.full_version.startswith(SUPPORTED_SCIPY_PREFIX):
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msg = f'The active scipy version "{sc.version.full_version}" has not been tested with the "sci_constants.py" module, which only supports scipy version(s prefixed with) "{SUPPORTED_SCIPY_PREFIX}". While the module may otherwise work, constants available in other versions of scipy may not conform to hard-coded unit lookups; as such, we throw an error, to ensure the absence of unfortunate resulting bugs'
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raise RuntimeError(msg)
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####################
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# - Fundamental Constants
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####################
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vac_speed_of_light = sp.nsimplify(sc.constants.speed_of_light) * spu.meter / spu.second
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hartree_energy = (
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sp.nsimplify(sc.constants.physical_constants['Hartree energy in eV'][0])
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* spu.electronvolt
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)
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####################
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# - Parse scipy.constants
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####################
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_SCIPY_EXCLUDED_ENTRIES: set[str] = {
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'Faraday constant for conventional electric current',
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}
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_SCIPY_COMBINED_UNITS: dict[str, tuple[str]] = {
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name: tuple(cst[1].split(' '))
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for name, cst in sc.constants.physical_constants.items()
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if cst[1] and name not in _SCIPY_EXCLUDED_ENTRIES
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}
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## TODO: Better interface to the official Units section? See https://docs.scipy.org/doc/scipy/reference/constants.html#units
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SCIPY_UNIT_TO_SYMPY_UNIT = {
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#'C_90': spu.coulombs, ## "Conventional electric current"
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'H': spu.henry,
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'C^4': spu.coulombs**4,
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'm^4': spu.meters**4,
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'm^-1': 1 / spu.meter,
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'J^-3': 1 / spu.joules**3,
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's^-2': 1 / spu.second**2,
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'kg': spu.kilogram,
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'eV': spu.electronvolt,
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'GeV': 10**9 * spu.electronvolt,
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'S': spu.siemens,
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'(GeV/c^2)^-2': (10**9 * spu.electronvolt / vac_speed_of_light**2) ** -2,
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'GeV^-2': (10**9 * spu.electronvolt) ** -2,
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'E_h': hartree_energy,
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'Hz': spu.hertz,
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'MeV/c': (10**6 * spu.electronvolt) / vac_speed_of_light,
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'Pa': spu.pascal,
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'ohm': spu.ohms,
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'Wb': spu.weber,
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'W^-1': 1 / spu.watt,
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'u': spu.atomic_mass_constant,
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'm^-3': 1 / spu.meters**3,
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'J': spu.joules,
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'sr^-1': 1 / spu.steradian,
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'T^-1': 1 / spu.tesla,
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'C^2': spu.coulombs**2,
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'F': spu.farad,
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'MeV': 10**6 * spu.electronvolt,
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'J^-2': 1 / spu.joules**2,
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'mol^-1': 1 / spu.mole,
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'kg^-1': 1 / spu.kilogram,
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'T^-2': 1 / spu.tesla**2,
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'fm': spux.femtometer,
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'V^-1': 1 / spu.volt,
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'N': spu.newton,
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'A': spu.ampere,
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's^-1': 1 / spu.second,
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'lm': spux.lumen,
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'm^3': spu.meters**3,
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'm^2': spu.meters**2,
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'K^-1': 1 / spu.kelvin,
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'm^-2': 1 / spu.meters**2,
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'MHz': 10**6 * spu.hertz,
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'J^-1': 1 / spu.joules,
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'Hz^-1': 1 / spu.hertz,
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'm': spu.meter,
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'C^3': spu.coulombs**3,
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'K': spu.kelvin,
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'A^-2': 1 / spu.ampere**2,
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'T': spu.tesla,
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'K^-4': 1 / spu.kelvin**4,
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'W': spu.watt,
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'C': spu.coulombs,
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's': spu.second,
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'V': spu.volt,
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}
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####################
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# - Extract Units
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####################
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SCI_CONSTANT_UNITS = {
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name: functools.reduce(
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lambda a, b: a * SCIPY_UNIT_TO_SYMPY_UNIT[b],
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combined_unit,
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sp.S(1),
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)
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for name, combined_unit in _SCIPY_COMBINED_UNITS.items()
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}
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SCI_CONSTANTS_INFO = {
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name: {
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'units': SCI_CONSTANT_UNITS[name],
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'uncertainty': sc.constants.physical_constants[name][2],
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'scipy_units': sc.constants.physical_constants[name][1],
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}
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for name, combined_unit in _SCIPY_COMBINED_UNITS.items()
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}
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SCI_CONSTANTS_REF = (
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'[CODATA2018]',
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'CODATA Recommended Values of the Fundamental Physical Constants 2018.',
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'https://physics.nist.gov/cuu/Constants/',
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)
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SCI_CONSTANTS = {
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name: sc.constants.physical_constants[name][0] * SCI_CONSTANT_UNITS[name]
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for name, combined_unit in _SCIPY_COMBINED_UNITS.items()
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}
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