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Last modified: December 2013

URL: http://cxc.harvard.edu/sherpa/ahelp/get_conf.html
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AHELP for CIAO 4.9 Sherpa v1

get_conf

Context: confidence

Synopsis

Return information regarding the confidence method.

Syntax

get_conf()
get_conf_results()
get_conf_opt( [name] )

Description

get_conf

The get_conf command returns the list of current settings defining the confidence estimation method (see "ahelp conf"); these settings may be modified by the user. This function accepts no arguments. The returned information is:

  • eps - precision of resulting limits, default=0.01
  • fast - if 'True', the fit optimization method is switched to a faster option to reduce the time per fit; default=False, so that the current optimization method is used
  • max_rstat - maximum possible value of the reduced statistic, default=3
  • maxfits - maximum number of tries to fit the parameter space, default=5
  • maxiters- maximum number of tries to bracket desired limits, before returning, default=200
  • openinterval - how the confidence function should behave when it cannot locate the root within the open interval; see "ahelp conf" for a detailed explanation; default=False
  • parallel - switch which allows confidence to be run as a parallel process; default=True
  • numcores - number of cores to use when conf command is run in parallel
  • remin - if during search, a new fit statistic is found that is smaller than original best fit, the difference between new and original statistics must be greater than this value, default=0.01
  • sigma - to get 1, 2, or 3-sigma limits, default=1
  • soft_limits - a switch which allows the search to go all the way out to the hard parameter limits; if switched on, the search will be restricted to occur within the soft limits, which can be changed by the user, default=False
  • tol - tolerance for the fit, default=0.20000000000000001
  • verbose - print information to the screen?; default=False

get_conf_results

The get_conf_results command accesses results from the last run of the confidence command. The function accepts no arguments. The results include the following attributes:

  • datasets - Data sets in fit
  • methodname - Estimation method name
  • iterfitname - Iterative fitting method name, if one specified
  • fitname - Fitting method name
  • statname - Statistic name
  • sigma - Change in statistic
  • percent - % confidence interval corresponding to sigma
  • parnames - Model parameter names
  • parvals - Model parameter fit values
  • parmins - Model parameter minimum values
  • parmaxes - Model parameter maximum values
  • warnings - Warning messages

get_conf_opt

The get_conf_opt command returns the value of a confidence option by name. If the name isn't specified, it returns a dictionary of all options that govern how confidence is run. The confidence options are modified using the set_conf_opt command.

  • eps - precision of resulting limits, default=0.01
  • fast - if 'True', the fit optimization method is switched to a faster option to reduce the time per fit; default=False, so that the current optimization method is used
  • max_rstat - maximum possible value of the reduced statistic, default=3
  • maxfits - maximum number of tries to fit the parameter space, default=5
  • maxiters- maximum number of tries to bracket desired limits, before returning, default=200
  • openinterval - how the confidence function should behave when it cannot locate the root within the open interval; see "ahelp conf" for a detailed explanation; default=False
  • parallel - switch which allows confidence to be run as a parallel process; default=True
  • numcores - number of cores to use when conf command is run in parallel
  • remin - if during search, a new fit statistic is found that is smaller than original best fit, the difference between new and original statistics must be greater than this value, default=0.01
  • sigma - to get 1, 2, or 3-sigma limits, default=1
  • soft_limits - a switch which allows the search to go all the way out to the hard parameter limits; if switched on, the search will be restricted to occur within the soft limits, which can be changed by the user, default=False
  • tol - tolerance for the fit, default=0.20000000000000001
  • verbose - print information to the screen?; default=False

Example 1

sherpa> get_conf()

Return a variable listing all of the settings that govern how the confidence method calculates confidence limits. Sample output is:

sherpa> print(get_conf())
name         = confidence
verbose      = False
openinterval = False
max_rstat    = 3
maxiters     = 200
soft_limits  = False
eps          = 0.01
fast         = False
maxfits      = 5
remin        = 0.01
tol          = 0.2
sigma        = 1
parallel     = True
numcores     = 2

sherpa> set_conf_opt("maxiters",300)

sherpa> print(get_conf())
name         = confidence
verbose      = False
openinterval = False
max_rstat    = 3
maxiters     = 300
soft_limits  = False
eps          = 0.01
fast         = False
maxfits      = 5
remin        = 0.01
tol          = 0.2
sigma        = 1
parallel     = True
numcores     = 2

Example 2

sherpa> get_conf_results()

Return a variable listing all of the results from the last run of the confidence command. Sample output is:

sherpa-> print(get_conf_results())
datasets    = (1,)
methodname  = confidence
iterfitname = none
fitname     = levmar
statname    = chi2gehrels
sigma       = 1
percent     = 68.2689492137
parnames    = ('p1.gamma', 'p1.ampl')
parvals     = (2.1585155113403327, 0.00022484014787994827)
parmins     = (-0.082785567348122591, -1.4825550342799376e-05)
parmaxes    = (0.083410634144100104, 1.4825550342799376e-05)
nfits       = 13

Example 3

sherpa> get_conf_opt()
sherpa> get_conf_opt("sigma")
1

When called without a specific option name, the get_conf_opt command returns the dictionary of all options that govern how confidence is run. If an option name such as "sigma" is specified, it returns the value of the sigma option, which is "1" in this example. Sample output of get_conf_opt() is:

sherpa> print(get_conf_opt())
{'verbose': False, 'openinterval': False, 'max_rstat': 3, 'maxiters': 200, 'soft_limits': False, 'eps': 0.01, 'fast': False, 'maxfits': 5, 'remin': 0.01, 'tol': 0.20000000000000001, 'sigma': 1, ''numcores': 2, parallel': True}

Bugs

See the bugs pages on the Sherpa website for an up-to-date listing of known bugs.

See Also

confidence
conf, covariance, get_covar, get_int_proj, get_int_unc, get_proj, get_reg_proj, get_reg_unc, int_proj, int_unc, projection, reg_proj, reg_unc, set_conf_opt, set_covar_opt, set_proj_opt
contrib
get_chart_spectrum
data
get_areascal, get_arf, get_arf_plot, get_axes, get_backscal, get_bkg, get_bkg_plot, get_bkg_scale, get_coord, get_counts, get_data, get_data_plot, get_dep, get_dims, get_error, get_exposure, get_grouping, get_indep, get_quality, get_rmf, get_specresp, get_staterror, get_syserror
filtering
get_filter
fitting
calc_stat_info, get_fit, get_stat_info
info
get_default_id, list_stats
methods
get_draws, get_iter_method_name, get_iter_method_opt, get_method
modeling
get_model, get_model_component, get_model_component_image, get_model_component_plot, get_model_plot, get_num_par, get_order_plot, get_par, get_pileup_model, get_response, get_source, get_source_component_image, get_source_component_plot, image_source
plotting
get_split_plot
psfs
get_kernel, get_psf
statistics
get_chisqr_plot, get_delchi_plot, get_prior, get_sampler, get_stat
utilities
get_analysis, get_rate
visualization
get_ratio, get_resid, image_getregion

Last modified: December 2013
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