The Units System¶
Most of these functions can be acccessed directly from Solcore:
>>> from solcore import eV
>>> print(eV(1e-19))
0.624 eV
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solcore.units_system.units_system.
generateConversionDictForSISuffix
(suffix, centi=False, deci=False, non_base_si_factor=1)[source]¶
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class
solcore.units_system.units_system.
UnitsSystem
(sources: Optional[Callable] = None)[source]¶ 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’)
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read
(source=None, value=None)[source]¶ Reads the units file and creates a database with all units and conversion factors.
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siUnits
(value, unit)[source]¶ Convert value from unit to equivalent si-unit
>>> print(siUnits(1,"mm")) # yields meters 0.001 >>> print(siUnits(1,"um")) # yields meters 1e-06
Parameters: - value – the value to convert
- unit – the units of the value
Returns: the value expresed in SI units
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asUnit
(value, unit)[source]¶ Converts from si unit to other unit. It is the reversed of siUnits function
>>> print(asUnit(1, "mA")) # print 1A in mA. 1000.0
Parameters: - value – the value to convert, assumed in SI units
- unit – the new units
- dimension – the value expressed in the new units.
Returns:
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siUnitFromString
(string)[source]¶ 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
Parameters: string – the string to convert Returns: the value in SI units
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convert
(value, from_unit, to_unit)[source]¶ 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
Parameters: - value – the value ot convert
- from_unit – the original unit
- to_unit – the final unit
Returns: the value expressed in the final unit
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eVnm
(value)[source]¶ Bi-directional conversion between nm and eV.
>>> print('%.3f'%eVnm(1000)) 1.240 >>> print('%i'%round(eVnm(1))) 1240
Parameters: value – a number with units [nm] or [eV]. Returns: either the conversion [nm] –> [eV], or [eV] –> [nm]
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nmJ
(value)[source]¶ Bi-directional conversion between nm and J.
>>> print(nmJ(1000)) 1.9864452126e-19 >>> print(nmJ(2e-18)) 99.3222606298
Parameters: value – a number with units [nm] or [J]. Returns: either the conversion [nm] –> [J], or [J] –> [nm]
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mJ
(value)[source]¶ Bi-directional conversion between m and J.
>>> print(mJ(1000)) 1.986445212595144e-25 >>> print(mJ(2e-18)) 9.93222606297572e-08
Parameters: value – a number with units [m] or [J]. Returns: either the conversion [m] –> [J], or [J] –> [m]
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nmHz
(value)[source]¶ Bi-directional conversion between nm and Hz.
Parameters: value – a number with units [nm] or [Hz]. Returns: Either a number which is the conversion [nm] –> [Hz] or [Hz] –> [nm]
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spectral_conversion_nm_ev
(x, y)[source]¶ 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
Parameters: - x – abscissa of the spectrum in units of [nm] or [eV]
- y – ordinate of the spectrum in units of [something/nm] or [something/eV]
Returns: A tuple (x, y) which has units either [eV, something/eV] or [nm. something/nm].
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spectral_conversion_nm_hz
(x, y)[source]¶ 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
Parameters: - x – abscissa of the spectrum in units of [nm] or [Hz]
- y – ordinate of the spectrum in units of [something/nm] or [something/Hz]
Returns: A tuple (x, y) which has units either [eV, something/nm] or [nm. something/Hz].
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sensibleUnits
(value, dimension, precision=2)[source]¶ 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
Parameters: - value – The value to re-calculate in SI units
- dimension – The dimension of the value. Possible values are: ‘luminous intensity’, ‘pressure’, ‘time’, ‘angle’, ‘temperature’, ‘current’, ‘force’, ‘charge’, ‘power’, ‘voltage’, ‘resistance’, ‘mass’, ‘length’, ‘energy’
- precision – Precission of the converted value.
Returns: A string with the value in the more ‘sensible’ units and the units.
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eV
(e)[source]¶ Transform an energy value in SI units in a string expresing the value in eV.
>>> print(eV(1e-19)) 0.624 eV
Parameters: e – Energy value in SI units Returns: A string with the energy converted in eV and its units.
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solcore.units_system.units_system.
compare_floats
(a, b, absoulte_precision=1e-12, relative_precision=None)[source]¶ 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.