FitResults

class sherpa.fit.FitResults(fit, results, init_stat, param_warnings)

Bases: sherpa.utils.NoNewAttributesAfterInit

The results of a fit.

This object contains the parameter values, information on the statistic and optimisation-method used, and other relevant information.

Changed in version 4.10.1: The covarerr attribute has been renamed to covar and now contains the covariance matrix estimated at the best-fit location, if provided by the optimiser.

datasets

sequence of int or str, or None – A sequence of the data set ids included in the results.

itermethodname

str or None – What iterated-fit scheme was used, if any.

methodname

str – The name of the optimisation method used (in lower case).

statname

str – The name of the statistic function.

succeeded

bool – Was the fit successful (did it converge)?

parnames

tuple of str – the parameter names that were varied in the fit (the thawed parameters in the model expression).

parvals

tuple of number – The parameter values, in the same order as parnames.

statval

number – The statistic value after the fit.

istatval

number – The statistic value at the start of the fit.

dstatval

number – The change in the statistic value (istatval - statval).

numpoints

int – The number of bins used in the fits.

dof

int – The number of degrees of freedom in the fit (the number of bins minus the number of free parameters).

qval

number or None – The Q-value (probability) that one would observe the reduced statistic value, or a larger value, if the assumed model is true and the current model parameters are the true parameter values. This will be None if the value can not be calculated with the current statistic (e.g. the Cash statistic).

rstat

number or None – The reduced statistic value (the statval field divided by dof). This is not calculated for all statistics.

message

str – A message about the results of the fit (e.g. if the fit was unable to converge). The format and contents depend on the optimisation method.

nfev

int – The number of model evaluations made during the fit.

extra_output

The extra_output field from the fit.

covar

tuple or None – The covariance matrix from the best-fit location, if provided by the optimiser.

modelvals

NumPy array – The values of the best-fit model evaluated for the data.

Methods Summary

format()

Return a string representation of the fit results.

Methods Documentation

format()

Return a string representation of the fit results.

Returns:txt – A multi-line representation of the fit results. Return type:str