# HOD¶

class cosmo_utils.mock_catalogues.hod_funcs.HOD(**kwargs)[source] [edit on github]

Bases: object

Computes various statistics corresponding to a given set of HOD parameters. HOD stands for Halo Occupation Distribution [http://arxiv.org/abs/astro-ph/0109001].

Parameters: use_identity : bool, optional If True, it uses the identity of expectation values, i.e.  + = . If False, it returns the number of galaxies by computing the total number of central and satellite galaxies. This variable is set to ‘True’ by default. log_m0 : float Halo mass, below which there are no satellite galaxies. log_m1 : float Mass scale where haloes contain one satellite galaxy on average. log_Mmin : float Minimum halo mass that can host a central galaxy. sigma_logM : float Scatter around Mmin alpha : float Slope of the power-law occupation function at high masses. mass_bin : float, optional Bin/step size of the logarithmic halo mass array. This variable is set to 0.01 by default. log_mhalo_min : float, optional Minimum logarithmic halo mass to consider. This variable is set to 10. by default. log_mhalo_max : float, optional Maximum logarithmic halo mass to consider. This variable is set to 15. by default.

Methods Summary

 ncen_avg() Computes the average number of central galaxies as function of halo mass. ngals_avg([arr_len, bin_statval, …]) Computes the average number of galaxies (centrals + satellites) as function of halo mass. ngals_avg_pd_create() Creates a DataFrame with the information of mass and the average numbers of 1) Centrals, 2) satellites, and 3) all galaxies. nsat_avg() Computes the average number of central galaxies as function of halo mass.

Methods Documentation

ncen_avg()[source] [edit on github]

Computes the average number of central galaxies as function of halo mass.

Returns: ncen_avg_arr : numpy.ndarray Array of average number of central galaxies as function of halo mass.
ngals_avg(arr_len=10, bin_statval='left', return_pd_dict=True, use_identity=True)[source] [edit on github]

Computes the average number of galaxies (centrals + satellites) as function of halo mass.

Parameters: arr_len : init, optional Minimum number of elements in each bin of x. This variable is set to 0 by default. return_pd_dict : bool If True, it returns a dictionary with pd.DataFrames for each of the statistics. ngal_choice : numpy.ndarray Array of total number of galaxies. This variable depends on the choice of use_identity.
ngals_avg_pd_create()[source] [edit on github]

Creates a DataFrame with the information of mass and the average numbers of 1) Centrals, 2) satellites, and 3) all galaxies.

Returns: gals_pd : pandas.DataFrame DataFrame containing info about the average numbers of different types of galaxies and their corresponding halo masses.
nsat_avg()[source] [edit on github]

Computes the average number of central galaxies as function of halo mass.

Returns: nsat_avg_arr : numpy.ndarray Array of average number of central galaxies as function of halo mass.