from collections import defaultdict
import re # tools to manage regular expresions
import numpy as np
from typing import Optional, Callable
import solcore
from solcore.source_managed_class import SourceManagedClass
from solcore.constants import *
[docs]class UnitError(Exception):
def __init__(self, msg):
BaseException.__init__(self, msg)
[docs]class WrongDimensionError(Exception):
def __init__(self, msg):
BaseException.__init__(self, msg)
[docs]def generateConversionDictForSISuffix(suffix, centi=False, deci=False, non_base_si_factor=1):
prefixes = "Y,Z,E,P,T,G,M,k,,m,u,n,p,f,a,z,y".split(",")
exponents = list(range(8, -9, -1))
if centi:
prefixes.append("c")
exponents.append(-2. / 3.)
if deci:
prefixes.append("d")
exponents.append(-1. / 3.)
unitNames = ["%s%s" % (prefix, suffix) for prefix in prefixes]
conversion = [1000. ** exponent * non_base_si_factor for exponent in exponents]
return dict(zip(unitNames, conversion))
[docs]class UnitsSystem(SourceManagedClass):
""" Contains all the functions related with the conversion of units. While defined inside this class, most of these
functions are available outside it, being decorated with 'breakout' (see 'Singleton')"""
def __init__(self, sources: Optional[Callable] = None):
super().__init__({k: sources(k) for k in sources()})
self.separate_value_and_unit_RE = re.compile(u"([-+]?[0-9]*\.?[0-9]+(?:[eE][-+]?[0-9]+)?)(?:[ \t]*(.*))?")
self.split_units_RE = re.compile(u"(?:([^ \+\-\^\.0-9]+)[\^]?([\-\+]?[^ \-\+]*)?)")
self.siConversions = {}
self.dimensions = defaultdict(dict)
self.read()
[docs] def read(self, source=None, value=None):
""" Reads the units file and creates a database with all units and conversion factors. """
if source is not None:
super().read(source, value)
for dimension in self.database.sections():
units = self.database.options(dimension)
for unit in units:
if "META_GenerateConversions" in unit:
expression = self.database.get(dimension, unit)
si_base_unit = expression.split()[0]
centi = "centi" in expression
deci = "deci" in expression
non_base_si_factor = self.safe_eval(expression.split()[1]) if "altbase" in expression else 1
dimension_conversions = generateConversionDictForSISuffix(
si_base_unit,
centi=centi,
deci=deci,
non_base_si_factor=non_base_si_factor
)
self.siConversions.update(dimension_conversions)
self.dimensions[dimension].update(dimension_conversions)
continue
string_expression = self.database.get(dimension, unit)
self.siConversions[unit] = self.safe_eval(string_expression)
self.dimensions[dimension][unit] = self.siConversions[unit]
[docs] def safe_eval(self, string_expression):
return eval(string_expression, {"__builtins__": {}}, {"constants": solcore.constants})
[docs] def siUnits(self, value, unit):
""" Convert value from unit to equivalent si-unit
>>> print(siUnits(1,"mm")) # yields meters
0.001
>>> print(siUnits(1,"um")) # yields meters
1e-06
:param value: the value to convert
:param unit: the units of the value
:return: the value expresed in SI units
"""
if unit is None or value is None:
return value
units_list = self.split_units_RE.findall(unit)
for unit, power in units_list:
power = float(power) if power != '' else 1
value = value * np.power((self.siConversions[unit]),
power) ### caution, *= is WRONG because it modifies original obj. DO NOT WANT
return value
[docs] def asUnit(self, value, unit):
""" Converts from si unit to other unit. It is the reversed of siUnits function
>>> print(asUnit(1, "mA")) # print 1A in mA.
1000.0
:param value: the value to convert, assumed in SI units
:param unit: the new units
:param dimension: the value expressed in the new units.
:return:
"""
if unit is None or value is None:
return value
units_list = self.split_units_RE.findall(unit)
for unit, power in units_list:
power = float(power) if power != '' else 1
value = value / (self.siConversions[unit]) ** power ### caution, /= is WRONG because it modifies original obj. DO NOT WANT
return value
[docs] def si(self, *args):
""" Utility function that forwards to either siUnit or siUnitFromString"""
if type(args[0]) == str:
return self.siUnitFromString(*args)
return self.siUnits(*args)
[docs] def siUnitFromString(self, string):
""" Converts a string of a number with units into si units of that quantity
>>> print(si("5 mm s-1")) # output in m/s
0.005
>>> print(si("5e-0mm-2")) # output in m2
5000000.0
>>> print(si("5"))
5.0
:param string: the string to convert
:return: the value in SI units
"""
# if unit is None or value is None:
# return value
matchObj = self.separate_value_and_unit_RE.match(string)
value, unit = matchObj.groups()
value = float(value)
units_list = self.split_units_RE.findall(unit)
for unit, power in units_list:
power = float(power) if power != '' else 1
value *= (self.siConversions[unit]) ** power
return value
[docs] def convert(self, value, from_unit, to_unit):
""" Converts between comparable units, does NOT check if units are comparable.
>>> print(convert(1, "nm", "mm"))
1e-06
>>> print(convert(1, "um", "nm"))
1000.0
>>> print(convert(1, "cm s-1", "km h-1"))
0.036
:param value: the value ot convert
:param from_unit: the original unit
:param to_unit: the final unit
:return: the value expressed in the final unit
"""
return self.asUnit(self.siUnits(value, from_unit), to_unit)
[docs] def eVnm(self, value):
""" Bi-directional conversion between nm and eV.
>>> print('%.3f'%eVnm(1000))
1.240
>>> print('%i'%round(eVnm(1)))
1240
:param value: a number with units [nm] or [eV].
:return: either the conversion [nm] --> [eV], or [eV] --> [nm]
"""
factor = self.asUnit(h, "eV") * self.asUnit(c, "nm")
return factor / value
[docs] def nmJ(self, value):
""" Bi-directional conversion between nm and J.
>>> print(nmJ(1000))
1.9864452126e-19
>>> print(nmJ(2e-18))
99.3222606298
:param value: a number with units [nm] or [J].
:return: either the conversion [nm] --> [J], or [J] --> [nm]
"""
factor = h * c
return factor / self.siUnits(value, "nm")
[docs] def mJ(self, value):
""" Bi-directional conversion between m and J.
>>> print(mJ(1000))
1.986445212595144e-25
>>> print(mJ(2e-18))
9.93222606297572e-08
:param value: a number with units [m] or [J].
:return: either the conversion [m] --> [J], or [J] --> [m]
"""
factor = h * c
return factor / value
[docs] def nmHz(self, value):
""" Bi-directional conversion between nm and Hz.
:param value: a number with units [nm] or [Hz].
:return: Either a number which is the conversion [nm] --> [Hz] or [Hz] --> [nm]
"""
factor = self.asUnit(c, "nm s-1")
return factor / value
[docs] def spectral_conversion_nm_ev(self, x, y):
""" Bi-directional conversion between a spectrum per nanometer and a spectrum per electronvolt.
Example:
1) nm --> eV conversion
wavelength_nm
photon_flux_per_nm
energy_ev, photon_flux_per_ev = spectral_conversion_nm_ev(wavelength_nm, photon_flux_per_nm)
2) eV --> nm conversion
energy_ev
photon_flux_per_ev
wavelength_nm, photon_flux_per_nm = spectral_conversion_nm_ev(energy_ev, photon_flux_per_ev)
Discussion:
A physical quantities such as total number of photon in a spectrum or
total energy of a spectrum should remain invariant after a transformation
to different units. This is called a spectral conversion. This function
is bi-directional because the mathematics of the conversion processes
is symmetrical.
>>> import numpy as np
>>> x = np.array([1,2,3])
>>> y = np.array([1,1,1])
>>> area_before = np.trapz(y, x=x)
>>> x_new, y_new = spectral_conversion_nm_ev(x, y)
>>> area_after = np.trapz(y_new, x=x_new)
>>> compare_floats(area_before, area_after, relative_precision=0.2)
True
:param x: abscissa of the spectrum in units of [nm] or [eV]
:param y: ordinate of the spectrum in units of [something/nm] or [something/eV]
:return: A tuple (x, y) which has units either [eV, something/eV] or [nm. something/nm].
"""
x_prime = self.eVnm(x)
conversion_constant = self.asUnit(h, "eV s") * self.asUnit(c, "nm s-1")
y_prime = y * conversion_constant / x_prime ** 2
y_prime = reverse(y_prime) # Wavelength ascends as electronvolts decends therefore reverse arrays
x_prime = reverse(x_prime)
return (x_prime, y_prime)
[docs] def spectral_conversion_nm_hz(self, x, y):
""" Bi-directional conversion between a spectrum per nanometer and a spectrum per Hertz.
Example:
1) nm --> Hz conversion
wavelength_nm
photon_flux_per_nm
energy_hz, photon_flux_per_hz = spectral_conversion_nm_hz(wavelength_nm, photon_flux_per_nm)
2) Hz --> nm conversion
energy_hz
photon_flux_per_hz
wavelength_nm, photon_flux_per_nm = spectral_conversion_nm_ev(energy_hz, photon_flux_per_hz)
Discussion:
A physical quantities such as total number of photon in a spectrum or
total energy of a spectrum should remain invariant after a transformation
to different units. This is called a spectral conversion. This function
is bi-directional because the mathematics of the conversion processes
is symmetrical.
>>> import numpy as np
>>> x = np.array([1,2,3])
>>> y = np.array([1,1,1])
>>> area_before = np.trapz(y, x=x)
>>> x_new, y_new = spectral_conversion_nm_hz(x, y)
>>> area_after = np.trapz(y_new, x=x_new)
>>> compare_floats(area_before, area_after, relative_precision=0.2)
True
:param x: abscissa of the spectrum in units of [nm] or [Hz]
:param y: ordinate of the spectrum in units of [something/nm] or [something/Hz]
:return: A tuple (x, y) which has units either [eV, something/nm] or [nm. something/Hz].
"""
x_prime = self.nmHz(x)
conversion_constant = self.asUnit(c, "nm s-1")
y_prime = y * conversion_constant / x_prime ** 2
y_prime = reverse(y_prime) # Wavelength ascends as frequency decends therefore reverse arrays
x_prime = reverse(x_prime)
return (x_prime, y_prime)
[docs] def sensibleUnits(self, value, dimension, precision=2):
""" Attempt to convert a physical quantity of a particular dimension to the most sensible units
>>> print(sensibleUnits(0.001,"length",0))
1 mm
>>> print(sensibleUnits(1000,"length",0))
1 km
>>> print(sensibleUnits(si("0.141 days"),"time", 5))
3.38400 h
:param value: The value to re-calculate in SI units
:param dimension: The dimension of the value. Possible values are: 'luminous intensity', 'pressure', 'time',
'angle', 'temperature', 'current', 'force', 'charge', 'power', 'voltage', 'resistance', 'mass', 'length', 'energy'
:param precision: Precission of the converted value.
:return: A string with the value in the more 'sensible' units and the units.
"""
negative = ""
if value < 0:
value *= -1
negative = "-"
formatting = "%s%%.%if %%s" % (negative, precision)
d = self.dimensions[dimension]
possibleUnits = d.keys()
if value == 0:
return formatting % (0, "")
allValues = [abs(np.log10(self.asUnit(value, unit))) for unit in possibleUnits]
bestUnit = possibleUnits[allValues.index(min(allValues))]
return formatting % (self.asUnit(value, bestUnit), bestUnit)
[docs] def eV(self, e):
""" Transform an energy value in SI units in a string expresing the value in eV.
>>> print(eV(1e-19))
0.624 eV
:param e: Energy value in SI units
:return: A string with the energy converted in eV and its units.
"""
return "%.3f eV" % self.asUnit(e, "eV")
[docs] def guess_dimension(self, unit):
""" Guess the dimension of a unit.
>>> print guess_dimension("nm")
length
:param unit: the unit.
:return: None
"""
possibilities = [key for key in self.dimensions.keys() if unit in self.dimensions[key]]
assert len(possibilities) != 0, "Guessing dimension of '%s': No candidates found" % unit
assert len(
possibilities) == 1, "Guessing dimension of '%s': Multiple candidates found, please convert manually. (%s)" % (
unit, ", ".join(possibilities))
return possibilities[0]
[docs] def list_dimensions(self):
for dim in self.dimensions.keys():
print(
"%s: %s" % (dim, ", ".join([k for k in self.dimensions[dim].keys() if k is not None and k != ""])))
[docs]def compare_floats(a, b, absoulte_precision=1e-12, relative_precision=None):
""" Returns true if the absolute difference between the numbers a and b is less than the precision.
Arguments:
a -- a float
b -- a float
Keyword Arguments (optional):
absolute_precision -- the absolute precision, abs(a-b) of the comparison.
relative_precision -- the relative precision, max(a,b)/min(a,b) - 1. of the comparison.
Returns:
True if the numbers are the same within the limits of the precision.
False if the number are not the same within the limits of the precision.
"""
if relative_precision is None:
absolute = abs(a - b)
if absolute < absoulte_precision:
return True
else:
return False
else:
relative = max(a, b) / min(a, b) - 1.
if relative < relative_precision:
return True
else:
return False
[docs]def independent_nm_ev(x, y):
return UnitsSystem().eVnm(x)[::-1], y[::-1]
[docs]def independent_nm_J(x, y):
return UnitsSystem().nmJ(x)[::-1], y[::-1]
[docs]def independent_m_J(x, y):
return reverse(UnitsSystem().mJ(x)), reverse(y)
[docs]def reverse(x):
return x[::-1]
if __name__ == '__main__':
UnitsSystem()
print(solcore.eVnm(1240))
