py21cmfast.SimulationOptions

class py21cmfast.SimulationOptions

Bases: InputStruct

Structure containing broad simulation options.

Parameters:

  • HII_DIM (int, optional) – Number of cells for the low-res box (after smoothing the high-resolution matter field). Default 256.

  • HIRES_TO_LOWRES_FACTOR (float, optional) – The ratio of the high-resolution box dimensionality to the low-resolution box dimensionality (i.e. DIM/HII_DIM). Use this parameter to define the size as a fixed ratio, instead of specifying DIM explicitly. This is useful if the parameters will be later evolved, so that specifying a new HII_DIM keeps the fixed resolution. By default, this is None, and a default of DIM=3*HII_DIM is used. This should be at least 3, and generally an integer (though this is not enforced).

  • DIM (int, optional) – Number of cells for the high-res box (sampling ICs) along a principal axis. In general, prefer setting HIRES_TO_LOWRES_FACTOR instead of DIM directly. Setting both will raise an error.

  • LOWRES_CELL_SIZE_MPC (float, optional) – The cell size of the low-resolution boxes (i.e. after smoothing the high-resolution matter field). Use either this parameter or BOX_LEN, setting both will raise an error. This parameter is generally preferrable, as it allows you to evolve the HII_DIM later, and keep the same resolution (automatically scaling up BOX_LEN). Default is None, falling back on a cell size of 1.5 Mpc.

  • BOX_LEN (float, optional) – Length of the box, in Mpc. Prefer setting LOWRES_CELL_SIZE_MPC, which automatically defines this setting. Specifying both will result in an error. By default, the BOX_LEN will be calculated as 1.5 * HII_DIM.

  • NON_CUBIC_FACTOR (float, optional) – Factor which allows the creation of non-cubic boxes. It will shorten/lengthen the line of sight dimension of all boxes. NON_CUBIC_FACTOR * DIM/HII_DIM must result in an integer.

  • N_THREADS (int, optional) – Sets the number of processors (threads) to be used for performing 21cmFAST. Default 1.

  • SAMPLER_MIN_MASS (float, optional) – The minimum mass to sample in the halo sampler when SOURCE_MODEL is “CHMF-SAMPLER”, decreasing this can drastically increase both compute time and memory usage.

  • SAMPLER_BUFFER_FACTOR (float, optional) – The arrays for the halo sampler will have size of SAMPLER_BUFFER_FACTOR multiplied by the expected number of halos in the box. Ideally this should be close to unity but one may wish to increase it to test alternative scenarios

  • N_COND_INTERP (int, optional) – The number of condition bins in the inverse CMF tables.

  • N_PROB_INTERP (int, optional) – The number of probability bins in the inverse CMF tables.

  • MIN_LOGPROB (float, optional) – The minimum log-probability of the inverse CMF tables.

  • HALOMASS_CORRECTION (float, optional) – This provides a corrective factor to the mass-limited (SAMPLE_METHOD==0) sampling, which multiplies the expected mass from a condition by this number. The default value of 0.9 is calibrated to the mass-limited sampling on a timestep of ZPRIME_STEP_FACTOR=1.02. If ZPRIME_STEP_FACTOR is increased, this value should be set closer to 1. This factor is also used in the partition (SAMPLE_METHOD==2) sampler, dividing nu(M) of each sample drawn.

  • PARKINSON_G0 (float, optional) – Only used when SAMPLE_METHOD==3, sets the normalisation of the correction to the extended press-schecter used in Parkinson et al. 2008.

  • PARKINSON_y1 (float, optional) – Only used when SAMPLE_METHOD==3, sets the index of the sigma power-law term of the correction to the extended Press-Schechter mass function used in Parkinson et al. 2008.

  • PARKINSON_y2 (float, optional) – Only used when SAMPLE_METHOD==3, sets the index of the delta power-law term of the correction to the extended Press-Schechter mass function used in Parkinson et al. 2008.

  • Z_HEAT_MAX (float, optional) – Maximum redshift used in the Tk and x_e evolution equations. Temperature and x_e are assumed to be homogeneous at higher redshifts. Lower values will increase performance.

  • ZPRIME_STEP_FACTOR (float, optional) – Logarithmic redshift step-size used in the z’ integral. Logarithmic dz. Decreasing (closer to unity) increases total simulation time for lightcones, and for Ts calculations.

  • INITIAL_REDSHIFT (float, optional) – Initial redshift used to perturb field from

  • DELTA_R_FACTOR (float, optional) – The factor by which to decrease the size of the filter in DexM when creating halo catalogues.

  • DENSITY_SMOOTH_RADIUS (float, optional) – The radius of the smoothing kernel in Mpc.

  • DEXM_OPTIMIZE_MINMASS (float, optional) – The minimum mass of a halo for which to use the DexM optimization if DEXM_OPTIMIZE is True.

  • DEXM_R_OVERLAP (float, optional) – The factor by which to multiply the halo radius to determine the distance within which smaller halos are excluded.

  • CORR_STAR (float, optional) – Self-correlation length used for updating halo properties. To model the correlation in the SHMR between timesteps, we sample from a conditional bivariate gaussian with correlation factor given by exp(-dz/CORR_STAR). This value is placed in SimulationOptions since it is used in the halo sampler, and not in the ionization routines.

  • CORR_SFR (float, optional) – Self-correlation length used for updating star formation rate, see “CORR_STAR” for details.

  • CORR_LX (float, optional) – Self-correlation length used for updating xray luminosity, see “CORR_STAR” for details.

  • K_MAX_FOR_CLASS (float, optional) – Maximum wavenumber to run CLASS, in 1/Mpc. Becomes relevant only if matter_options.POWER_SPECTRUM = “CLASS”.

classmethod __init_subclass__()

Store each subclass for easy access.

Return type:

None

__str__()

Human-readable string representation of the object.

Return type:

str

asdict()

Return a dict representation of the instance.

Examples

This dict should be such that doing the following should work, i.e. it can be used exactly to construct a new instance of the same object:

>>> inp = InputStruct(**params)
>>> newinp =InputStruct(**inp.asdict())
>>> inp == newinp
Return type:

dict

clone(**kwargs)

Make a fresh copy of the instance with arbitrary parameters updated.

classmethod from_subdict(dct, safe=True)

Construct an instance of a parameter structure from a dictionary.

classmethod new(x=None, **kwargs)

Create a new instance of the struct.

Parameters:

x (dict | InputStruct | None) – Initial values for the struct. If x is a dictionary, it should map field names to their corresponding values. If x is an instance of this class, its attributes will be used as initial values. If x is None, the struct will be initialised with default values.

Other Parameters:

  • All other parameters should be passed as if directly to the class constructor

  • (i.e. as parameter names).

Parameters:

x (dict | Self | None)

Examples

>>> up = SimulationOptions({'HII_DIM': 250})
>>> up.HII_DIM
250
>>> up = SimulationOptions(up)
>>> up.HII_DIM
250
>>> up = SimulationOptions()
>>> up.HII_DIM
200
>>> up = SimulationOptions(HII_DIM=256)
>>> up.HII_DIM
256
property BOX_LEN: float

The size of the box along a side, in Mpc.

If not given explicitly, it is auto-calculated via HII_DIM * LOWRES_CELL_SIZE_MPC.

Return type:

float

CORR_LX: float
CORR_SFR: float
CORR_STAR: float
DELTA_R_FACTOR: float
DENSITY_SMOOTH_RADIUS: float
DEXM_OPTIMIZE_MINMASS: float
DEXM_R_OVERLAP: float
property DIM: int

The number of cells on a side of the hi-res box used for ICs.

If not given explicitly, it is auto-calculated via HII_DIM * HIRES_TO_LOWRES_FACTOR.

Return type:

int

HALOMASS_CORRECTION: float
HII_DIM: int
property HII_tot_num_pixels

Total number of pixels in the low-res box.

property HIRES_TO_LOWRES_FACTOR: float

The downsampling factor from high to low-res.

Return type:

float

INITIAL_REDSHIFT: float
K_MAX_FOR_CLASS: float | None
property LOWRES_CELL_SIZE_MPC: float

The cell size (in Mpc) of the low-res grids.

Return type:

float

MIN_LOGPROB: float
NON_CUBIC_FACTOR: float
N_COND_INTERP: int
N_PROB_INTERP: int
N_THREADS: int
PARKINSON_G0: float
PARKINSON_y1: float
PARKINSON_y2: float
SAMPLER_BUFFER_FACTOR: float
SAMPLER_MIN_MASS: float
ZPRIME_STEP_FACTOR: float
Z_HEAT_MAX: float
property cdict: dict

A python dictionary containing the properties of the wrapped C-struct.

The memory pointed to by this dictionary is not owned by the wrapped C-struct, but is rather just a python dict. However, in contrast to asdict(), this method transforms the properties to what they should be in C (e.g. linear space vs. log-space) before putting them into the dict.

This dict also contains only the properties of the wrapped C-struct, rather than all properties of the InputStruct instance (some attributes of the python instance are there only to guide setting of defaults, and don’t appear in the C-struct at all).

Return type:

dict

property cell_size: astropy.units.Quantity[astropy.units.Mpc]

The resolution of a low-res cell.

Return type:

astropy.units.Quantity[astropy.units.Mpc]

property cell_size_hires: astropy.units.Quantity[astropy.units.Mpc]

The resolution of a hi-res cell.

Return type:

astropy.units.Quantity[astropy.units.Mpc]

property cstruct: py21cmfast.wrapper.structs.StructWrapper

The object pointing to the memory accessed by C-code for this struct.

Return type:

py21cmfast.wrapper.structs.StructWrapper

property struct: py21cmfast.wrapper.structs.StructWrapper

The python-wrapped struct associated with this input object.

Return type:

py21cmfast.wrapper.structs.StructWrapper

property tot_fft_num_pixels

Total number of pixels in the high-res box.