Source code for scm.plams.tools.units

import collections
import math
import numpy as np

from ..core.errors import UnitsError


__all__ = ['Units']


[docs]class Units: """A singleton class for unit converter. All values are based on `2014 CODATA recommended values <http://physics.nist.gov/cuu/Constants>`_. The following constants and units are supported: * constants: - ``speed_of_light`` (also ``c``) - ``electron_charge`` (also ``e``) - ``Avogadro_constant`` (also ``NA``) - ``Bohr_radius`` * distance: - ``Angstrom``, ``A`` - ``Bohr``, ``au``, ``a.u.`` - ``nm`` - ``pm`` * reciprocal distance: - ``1/Angstrom``, ``1/A``, ``Angstrom^-1``, ``A^-1``, - ``1/Bohr``, ``Bohr^-1`` * angle: - ``degree``, ``deg``, - ``radian``, ``rad``, - ``grad`` - ``circle`` * energy: - ``au``, ``a.u.``, ``Hartree`` - ``eV`` - ``kcal/mol`` - ``kJ/mol`` - ``cm^-1``, ``cm-1`` * dipole moment: - ``au``, ``a.u.`` - ``Cm`` - ``Debye``, ``D`` Example:: >>> print(Units.constants['speed_of_light']) 299792458 >>> print(Units.constants['e']) 1.6021766208e-19 >>> print(Units.convert(123, 'angstrom', 'bohr')) 232.436313431 >>> print(Units.convert([23.32, 145.0, -34.7], 'kJ/mol', 'kcal/mol')) [5.573613766730401, 34.655831739961755, -8.293499043977056] >>> print(Units.conversion_ratio('kcal/mol', 'kJ/mol')) 4.184 """ constants = {} constants['Bohr_radius'] = 0.529177210903 #http://physics.nist.gov/cgi-bin/cuu/Value?bohrrada0 constants['Avogadro_constant'] = constants['NA'] = 6.022140857e23 #http://physics.nist.gov/cgi-bin/cuu/Value?na constants['speed_of_light'] = constants['c'] = 299792458 #http://physics.nist.gov/cgi-bin/cuu/Value?c constants['electron_charge'] = constants['e'] = 1.6021766208e-19 #http://physics.nist.gov/cgi-bin/cuu/Value?e distance = {} distance['A'] = distance['Angstrom'] = 1.0 distance['Bohr'] = distance['a.u.'] = distance['au'] = 1.0 / constants['Bohr_radius'] distance['nm'] = distance['A'] / 10.0 distance['pm'] = distance['A'] * 100.0 rec_distance = {} rec_distance['1/A'] = rec_distance['1/Angstrom'] = rec_distance['A^-1'] = rec_distance['Angstrom^-1'] = 1.0 rec_distance['1/Bohr'] = rec_distance['Bohr^-1'] = constants['Bohr_radius'] energy = {} energy['au'] = energy['a.u.'] = energy['Hartree'] = 1.0 energy['eV'] = 27.211386245988 #http://physics.nist.gov/cgi-bin/cuu/Value?hrev energy['kJ/mol'] = 4.359744650e-21 * constants['NA'] #http://physics.nist.gov/cgi-bin/cuu/Value?hrj energy['kcal/mol'] = energy['kJ/mol'] / 4.184 energy['cm^-1'] = energy['cm-1'] = 219474.6313702 #http://physics.nist.gov/cgi-bin/cuu/Value?hrminv angle = {} angle['degree'] = angle['deg'] = 1.0 angle['radian'] = angle['rad'] = math.pi / 180.0 angle['grad'] = 100.0 / 90.0 angle['circle'] = 1.0 / 360.0 dipole = {} dipole['au'] = dipole['a.u.'] = 1.0 dipole['Cm'] = constants['e'] * constants['Bohr_radius'] * 1e-10 dipole['Debye'] = dipole['D'] = dipole['Cm'] * constants['c']* 1e21 dicts = {} dicts['distance'] = distance dicts['energy'] = energy dicts['angle'] = angle dicts['dipole'] = dipole dicts['reciprocal distance'] = rec_distance
[docs] def __init__(self): raise UnitsError('Instances of Units cannot be created')
@classmethod def find_unit(cls, unit): ret = {} for quantity in cls.dicts: for k in cls.dicts[quantity]: if k.lower() == unit.lower(): ret[quantity] = k return ret
[docs] @classmethod def conversion_ratio(cls, inp, out): """Return conversion ratio from unit *inp* to *out*.""" inps = cls.find_unit(inp) outs = cls.find_unit(out) common = set(inps.keys()) & set(outs.keys()) if len(common) > 0: quantity = common.pop() d = cls.dicts[quantity] return d[outs[quantity]]/d[inps[quantity]] else: if len(inps) == 0 and len(outs) == 0: raise UnitsError("Unsupported units: '{}' and '{}'".format(inp, out)) if len(inps) > 0 and len(outs) > 0: raise UnitsError("Invalid unit conversion: '{}' is a unit of {} and '{}' is a unit of {}".format(inp, ', '.join(list(inps.keys())), out, ', '.join(list(outs.keys())))) else: #exactly one of (inps,outs) empty invalid, nonempty = (out,inps) if len(inps) else (inp,outs) if len(nonempty) == 1: quantity = list(nonempty.keys())[0] raise UnitsError("Invalid unit conversion: {} is not supported. Supported units for {}: {}".format(invalid, quantity, ', '.join(list(cls.dicts[quantity].keys())))) else: raise UnitsError("Invalid unit conversion: {} is not a supported unit for {}".format(invalid, ', '.join(list(nonempty.keys()))))
[docs] @classmethod def convert(cls, value, inp, out): """Convert *value* from unit *inp* to *out*. *value* can be a single number or a container (list, tuple, numpy.array etc.). In the latter case a container of the same type and length is returned. Conversion happens recursively, so this method can be used to convert, for example, a list of lists of numbers, or any other hierarchical container structure. Conversion is applied on all levels, to all values that are numbers (also numpy number types). All other values (strings, bools etc.) remain unchanged. """ if value is None or isinstance(value, (bool, str)): return value if isinstance(value, collections.abc.Iterable): t = type(value) if t == np.ndarray: t = np.array v = [cls.convert(i, inp, out) for i in value] return t(v) if isinstance(value, (int, float, np.generic)): return value * cls.conversion_ratio(inp,out) return value