rootpy.stats.Workspace

class rootpy.stats.Workspace(*args, **kwargs)

fit(data='obsData', model_config='ModelConfig', param_const=None, param_values=None, param_ranges=None, poi_const=False, poi_value=None, poi_range=None, extended=False, num_cpu=1, process_strategy=0, offset=False, print_level=None, return_nll=False, **kwargs)

Fit a pdf to data in a workspace

Parameters:

workspace : RooWorkspace

The workspace

data : str or RooAbsData, optional (default=’obsData’)

The name of the data or a RooAbsData instance.

model_config : str or ModelConfig, optional (default=’ModelConfig’)

The name of the ModelConfig in the workspace or a ModelConfig instance.

param_const : dict, optional (default=None)

A dict mapping parameter names to booleans setting the const state of the parameter

param_values : dict, optional (default=None)

A dict mapping parameter names to values

param_ranges : dict, optional (default=None)

A dict mapping parameter names to 2-tuples defining the ranges

poi_const : bool, optional (default=False)

If True, then make the parameter of interest (POI) constant

poi_value : float, optional (default=None)

If not None, then set the POI to this value

poi_range : tuple, optional (default=None)

If not None, then set the range of the POI with this 2-tuple

extended : bool, optional (default=False)

If True, add extended likelihood term (False by default)

num_cpu : int, optional (default=1)

Parallelize NLL calculation on multiple CPU cores. If negative then use all CPU cores. By default use only one CPU core.

process_strategy : int, optional (default=0)

Strategy 0: Divide events into N equal chunks.

Strategy 1: Process event i%N in process N. Recommended for binned data with a substantial number of zero-bins, which will be distributed across processes more equitably in this strategy.

Strategy 2: Process each component likelihood of a RooSimultaneous fully in a single process and distribute components over processes. This approach can be benificial if normalization calculation time dominates the total computation time of a component (since the normalization calculation must be performed in each process in strategies 0 and 1. However beware that if the RooSimultaneous components do not share many parameters this strategy is inefficient: as most minuit-induced likelihood calculations involve changing a single parameter, only 1 of the N processes will be active most of the time if RooSimultaneous components do not share many parameters.

Strategy 3: Follow strategy 0 for all RooSimultaneous components, except those with less than 30 dataset entries, for which strategy 2 is followed.

offset : bool, optional (default=False)

Offset likelihood by initial value (so that starting value of FCN in minuit is zero). This can improve numeric stability in simultaneously fits with components with large likelihood values.

print_level : int, optional (default=None)

The verbosity level for the minimizer algorithm. If None (the default) then use the global default print level. If negative then all non-fatal messages will be suppressed.

return_nll : bool, optional (default=False)

If True then also return the RooAbsReal NLL function that was minimized.

kwargs : dict, optional

Remaining keyword arguments are passed to the minimize function

Returns:

result : RooFitResult

The fit result.

func : RooAbsReal

If return_nll is True, the NLL function is also returned.

See also

minimize