tracts.driver_utils.compute_physical_start_params#

compute_physical_start_params(driver_spec, demographic_model, sex_bias_param_names, non_sex_bias_param_names, step_label='step 1')#

Computes physical starting parameters to optimize from. When driver_spec.optim.two_steps_optimization is True, only non-sex-bias parameters are sampled (sex-bias parameters are fixed at the midpoint of their admissible bounds – 0 with the default (-1, 1) bounds, or the midpoint of a user-narrowed range that may exclude 0, see bounds; or at any user-provided fixed value), matching step 1’s parameter subset, and identical starting points are collapsed into one (see collapse_identical_start_params). Otherwise, all parameters are sampled/fixed according to driver_spec.optim.fix_parameters_by_value alone.

Parameters:

  • driver_spec (InferenceConfig) – The driver-file configuration controlling repetitions/seed/two_steps_optimization/ fix_parameters_by_value.

  • demographic_model (ParametrizedDemography | ParametrizedDemographySexBiased) – The demographic model to sample starting parameters for.

  • sex_bias_param_names (list[str]) – Names of the sex-bias parameters among the demographic model’s free base parameters.

  • non_sex_bias_param_names (list[str]) – Names of the non-sex-bias parameters among the demographic model’s free base parameters.

  • step_label (str) – Label used when collapsing identical two-step starting parameters into one. Defaults to “step 1”.

Returns:

The physical starting parameters to optimize from.

Return type:

list[ndarray]