radis.lbl.factory module¶
Contains the SpectrumFactory
class, which is
the core of the RADIS Line-by-Line module.
Examples
Calculate a CO Spectrum, fetching the lines from HITRAN
# This is how you get a spectrum (see spectrum.py for front-end functions
# that do just that)
sf = SpectrumFactory(2125, 2249.9,
molecule='CO',
isotope=1,
cutoff=1e-30, # for faster calculations. See
# `plot_linestrength_hist` for more details
**kwargs)
sf.fetch_databank() # autodownload from HITRAN
s = sf.eq_spectrum(Tgas=300)
s.plot('abscoeff') # opacity
# Here we get some extra informations:
s.plot('radiance', wunit='nm',
Iunit='µW/cm2/sr/nm', # Iunit is arbitrary. Use whatever makes sense
show_points=True) # show_points to have an idea of the resolution
See radis.test.lbl.test_factory
for more examples
Routine Listing¶
(the following sections are marked on the slider bar in the Spyder IDE with the # XXX symbol)
PUBLIC METHODS
eq_spectrum()
>>> calc equilibrium spectrumnon_eq_spectrum()
>>> calc non equilibrium spectrumoptically_thin_power()
>>> get total power (equilibrium or non eq)
Most methods are written in inherited class with the following inheritance scheme:
DatabankLoader
> BaseFactory
>
BroadenFactory
> BandFactory
>
SpectrumFactory
Notes
Debugging:
Remember one can access all locals variable in a function either by running
%debug after a crash in IPython. Or by adding the line globals().update(locals())
at any point
Performance:
Fast version: iterate over chunks of dataframe Note that we can’t use the full dataframe because it’s too big and takes too much memory See Performance for more details.
for Developers:
To implement new database formats, see the databases parsers in cdsd.py / hitran.py, and the partition function interpolators / calculators methods of SpectrumFactory:
_build_partition_function_calculator()
and_build_partition_function_interpolator()
- class SpectrumFactory(wmin=None, wmax=None, wunit=<radis.misc.utils.Default object>, wavenum_min=None, wavenum_max=None, wavelength_min=None, wavelength_max=None, Tref=296, pressure=1.01325, mole_fraction=1, path_length=1, wstep=0.01, molecule=None, isotope='all', medium='air', broadening_max_width=10, pseudo_continuum_threshold=0, self_absorption=True, chunksize=None, optimization='simple', folding_thresh=1e-06, zero_padding=-1, broadening_method=<radis.misc.utils.Default object>, cutoff=0, verbose=True, warnings=True, save_memory=False, export_populations=None, export_lines=False, **kwargs)[source]¶
Bases:
radis.lbl.bands.BandFactory
A class to put together all functions related to loading CDSD / HITRAN databases, calculating the broadenings, and summing over all the lines.
- Parameters
wmin, wmax (float or
Quantity
) – a hybrid parameter which can stand for minimum (maximum) wavenumber or minimum (maximum) wavelength depending upon the unit accompanying it. If dimensionless,wunit
is considered as the accompanying unit.wunit (string) – the unit accompanying wmin and wmax. Can only be passed with wmin and wmax. Default is
cm-1
.wavenum_min, wavenum_max (float(cm^-1) or
Quantity
) – minimum (maximum) wavenumber to be processed in \(cm^{-1}\). use astropy.units to specify arbitrary inverse-length units.wavelength_min, wavelength_max (float(nm) or
Quantity
) – minimum (maximum) wavelength to be processed in \(nm\). This wavelength can be in'air'
or'vacuum'
depending on the value of the parametermedium=
. use astropy.units to specify arbitrary length units.pressure (float(bar) or
Quantity
) – partial pressure of gas in bar. Default 1.01325 (1 atm). use astropy.units to specify arbitrary pressure units. For example,1013.25 * u.mbar
.mole_fraction (N/D) – species mole fraction. Default 1. Note that the rest of the gas is considered to be air for collisional broadening.
path_length (float(cm) or
Quantity
) – path length in cm. Default 1. use astropy.units to specify arbitrary length units.molecule (int, str, or
None
) – molecule id (HITRAN format) or name. IfNone
, the molecule can be infered from the database files being loaded. See the list of supported molecules inMOLECULES_LIST_EQUILIBRIUM
andMOLECULES_LIST_NONEQUILIBRIUM
. DefaultNone
.isotope (int, list, str of the form ‘1,2’, or ‘all’) – isotope id (sorted by relative density: (eg: 1: CO2-626, 2: CO2-636 for CO2). See HITRAN documentation for isotope list for all species. If ‘all’, all isotopes in database are used (this may result in larger computation times!). Default ‘all’
medium (
'air'
,'vacuum'
) – propagating medium when giving inputs with'wavenum_min'
,'wavenum_max'
. Does not change anything when giving inputs in wavenumber. Default'air'
- Other Parameters
*Computation parameters (see :py:attr:`~radis.lbl.loader.DatabankLoader.params`)*
Tref (K) – Reference temperature for calculations (linestrength temperature correction). HITRAN database uses 296 Kelvin. Default 296 K
self_absorption (boolean) – Compute self absorption. If
False
, spectra are optically thin. DefaultTrue
.broadening_max_width (float (cm-1)) – Full width over which to compute the broadening. Large values will create a huge performance drop (scales as ~broadening_width^2 without DLM) The calculated spectral range is increased (by broadening_max_width/2 on each side) to take into account overlaps from out-of-range lines. Default
10
cm-1.wstep (float (cm-1) or
'auto'
) – Resolution of wavenumber grid. Default0.01
cm-1. If'auto'
, it is ensured that there are slightly more or less thanGRIDPOINTS_PER_LINEWIDTH_WARN_THRESHOLD
points for each linewidth.Note
wstep = ‘auto’ is optimized for performances while ensuring accuracy, but is still experimental in 0.9.30. Feedback welcome!
cutoff (float (~ unit of Linestrength: cm-1/(#.cm-2))) – discard linestrengths that are lower that this, to reduce calculation times.
1e-27
is what is generally used to generate databases such as CDSD. If0
, no cutoff. Default1e-27
.pseudo_continuum_threshold (float) – if not
0
, first calculate a rough approximation of the spectrum, then moves all lines whose linestrength intensity is less than this threshold of the maximum in a semi-continuum. Values above 0.01 can yield significant errors, mostly in highly populated areas. 80% of the lines can typically be moved in a continuum, resulting in 5 times faster spectra. If0
, no semi-continuum is used. Default0
.save_memory (boolean) – if
True
, removes databases calculated by intermediate functions (for instance, delete the full database once the linestrength cutoff criteria was applied). This saves some memory but requires to reload the database & recalculate the linestrength for each new parameter. DefaultFalse
.export_populations (
'vib'
,'rovib'
,None
) – if not None, store populations in Spectrum. Either store vibrational populations (‘vib’) or rovibrational populations (‘rovib’). DefaultNone
export_lines (boolean) – if
True
, saves details of all calculated lines in Spectrum. This is necessary to later useline_survey()
, but can take some space. DefaultFalse
.chunksize (int, or
None
) – Splits the lines database in several chuncks during calculation, else the multiplication of lines over all spectral range takes too much memory and slows the system down. Chunksize let you change the default chunck size. IfNone
, all lines are processed directly. Usually faster but can create memory problems. DefaultNone
optimization (
"simple"
,"min-RMS"
,None
) – If either"simple"
or"min-RMS"
DLM optimization for lineshape calculation is used: -"min-RMS"
: weights optimized by analytical minimization of the RMS-error (See: [Spectral-Synthesis-Algorithm]) -"simple"
: weights equal to their relative position in the gridIf using the DLM optimization, broadening method is automatically set to
'fft'
. IfNone
, no lineshape interpolation is performed and the lineshape of all lines is calculated.Refer to [Spectral-Synthesis-Algorithm] for more explanation on the DLM method for lineshape interpolation.
Default
"min-RMS"
folding_thresh (float) – Folding is a correction procedure thet is applied when the lineshape is calculated with the
fft
broadening method and the linewidth is comparable towstep
, that prevents sinc(v) modulation of the lineshape. Folding continues until the lineshape intensity is belowfolding_threshold
. Setting to 1 or higher effectively disables folding correction.Range: 0.0 < folding_thresh <= 1.0 Default: 1e-6
zero_padding (int) – Zero padding is used in conjunction with the
fft
broadening method to prevent circular convolution at the cost of performance. When set to -1, padding is set equal to the spectrum length, which guarantees a linear convolution.Range: 0 <= zero_padding <= len(w), or zero_padding = -1 Default: -1
broadening_method (
"voigt"
,"convolve"
,"fft"
) – Calculates broadening with a direct voigt approximation (‘voigt’) or by convoluting independantly calculated Doppler and collisional broadening (‘convolve’). First is much faster, 2nd can be used to compare results. This SpectrumFactory parameter can be manually adjusted a posteriori with:sf = SpectrumFactory(...) sf.params.broadening_method = 'voigt'
Fast fourier transform
'fft'
is only available if using the DLM lineshape calculationoptimization
. Because the DLM convolves all lines at the same time, and thus operates on large arrays,'fft'
becomes more appropriate than convolutions in real space ('voit'
,'convolve'
)By default, use
"fft"
for anyoptimization
, and"voigt"
if optimization isNone
.warnings (bool, or one of
['warn', 'error', 'ignore']
, dict) – If one of['warn', 'error', 'ignore']
, set the default behaviour for all warnings. Can also be a dictionary to set specific warnings only. Example:warnings = {'MissingSelfBroadeningWarning':'ignore', 'NegativeEnergiesWarning':'ignore', 'HighTemperatureWarning':'ignore'}
See
default_warning_status
for more information.verbose (boolean, or int) – If
False
, stays quiet. IfTrue
, tells what is going on. If>=2
, gives more detailed messages (for instance, details of calculation times). DefaultTrue
.
Examples
An example using
SpectrumFactory
,load_databank()
, theSpectrum
methods, andunits
from radis import SpectrumFactory from astropy import units as u sf = SpectrumFactory(wavelength_min=4165 * u.nm, wavelength_max=4200 * u.nm, isotope='1,2', broadening_max_width=10, # cm-1 medium='vacuum', verbose=1, # more for more details ) sf.load_databank('HITRAN-CO2-TEST') # predefined in ~/radis.json s = sf.eq_spectrum(Tgas=300 * u.K, path_length=1 * u.cm) s.rescale_path_length(0.01) # cm s.plot('radiance_noslit', Iunit='µW/cm2/sr/nm')
Refer to the online Examples for more cases.
See also
Alternative
,calc_spectrum()
,Main
,load_databank()
,eq_spectrum()
,non_eq_spectrum()
,For
,fetch_databank()
,init_databank()
,init_database()
,eq_bands()
,non_eq_bands()
,Inputs
- eq_spectrum(Tgas, mole_fraction=None, path_length=None, pressure=None, name=None)[source]¶
Generate a spectrum at equilibrium.
- Parameters
Tgas (float or
Quantity
) – Gas temperature (K)mole_fraction (float) – database species mole fraction. If None, Factory mole fraction is used.
path_length (float or
Quantity
) – slab size (cm). IfNone
, the default Factorypath_length
is used.pressure (float or
Quantity
) – pressure (bar). IfNone
, the default Factorypressure
is used.name (str) – output Spectrum name (useful in batch)
- Returns
s –
Returns a
Spectrum
object- Return type
References
- 1
RADIS doc: Spectrum how to?
See also
- eq_spectrum_gpu(Tgas, mole_fraction=None, path_length=None, pressure=None, name=None)[source]¶
Generate a spectrum at equilibrium with calculation of lineshapes and broadening done on the GPU.
Note
This method requires CUDA compatible hardware to execute. For more information on how to setup your system to run GPU-accelerated methods using CUDA and Cython, check
GPU Spectrum Calculation on RADIS
- Parameters
Tgas (float or
Quantity
) – Gas temperature (K)mole_fraction (float) – database species mole fraction. If None, Factory mole fraction is used.
path_length (float or
Quantity
) – slab size (cm). IfNone
, the default Factorypath_length
is used.pressure (float or
Quantity
) – pressure (bar). IfNone
, the default Factorypressure
is used.name (str) – output Spectrum name (useful in batch)
- Returns
s –
Returns a
Spectrum
object- Return type
See also
- non_eq_spectrum(Tvib, Trot, Ttrans=None, mole_fraction=None, path_length=None, pressure=None, vib_distribution='boltzmann', rot_distribution='boltzmann', overpopulation=None, name=None)[source]¶
Calculate emission spectrum in non-equilibrium case. Calculates absorption with broadened linestrength and emission with broadened Einstein coefficient.
- Parameters
Tvib (float) – vibrational temperature [K] can be a tuple of float for the special case of more-than-diatomic molecules (e.g: CO2)
Trot (float) – rotational temperature [K]
Ttrans (float) – translational temperature [K]. If None, translational temperature is taken as rotational temperature (valid at 1 atm for times above ~ 2ns which is the RT characteristic time)
mole_fraction (float) – database species mole fraction. If None, Factory mole fraction is used.
path_length (float or
Quantity
) – slab size (cm). IfNone
, the default Factorypath_length
is used.pressure (float or
Quantity
) – pressure (bar). IfNone
, the default Factorypressure
is used.
- Other Parameters
vib_distribution (
'boltzmann'
,'treanor'
) – vibrational distributionrot_distribution (
'boltzmann'
) – rotational distributionoverpopulation (dict, or
None
) –add overpopulation factors for given levels:
{level:overpopulation_factor}
name (str) – output Spectrum name (useful in batch)
- Returns
s –
Returns a
Spectrum
object- Return type
References
- 1
RADIS doc: Spectrum how to?
See also
- optically_thin_power(Tgas=None, Tvib=None, Trot=None, Ttrans=None, vib_distribution='boltzmann', rot_distribution='boltzmann', mole_fraction=None, path_length=None, unit='mW/cm2/sr')[source]¶
Calculate total power emitted in equilibrium or non-equilibrium case in the optically thin approximation: it sums all emission integral over the total spectral range.
Warning
this is a fast implementation that doesnt take into account the contribution of lines outside the given spectral range. It is valid for spectral ranges surrounded by no lines, and spectral ranges much broaded than the typical line broadening (~ 1-10 cm-1 in the infrared)
If what you’re looking for is an accurate simulation on a narrow spectral range you better calculate the spectrum (that does take all of that into account) and integrate it with
get_power()
- Parameters
Tgas (float) – equilibrium temperature [K] If doing a non equilibrium case it should be None. Use Ttrans for translational temperature
Tvib (float) – vibrational temperature [K]
Trot (float) – rotational temperature [K]
Ttrans (float) – translational temperature [K]. If None, translational temperature is taken as rotational temperature (valid at 1 atm for times above ~ 2ns which is the RT characteristic time)
mole_fraction (float) – database species mole fraction. If None, Factory mole fraction is used.
path_length (float) – slab size (cm). If None, Factory mole fraction is used.
unit (str) – output unit. Default
'mW/cm2/sr'
- Returns
float – see
unit=
.- Return type
Returns total power density in mW/cm2/sr (unless different unit is chosen),
See also