Chandra X-Ray Observatory
	(CXC)
Skip to the navigation links
Last modified: December 2013

URL: http://cxc.harvard.edu/sherpa/ahelp/get_indep.html
Jump to: Description · Examples · Bugs · See Also


AHELP for CIAO 4.9 Sherpa v1

get_indep

Context: data

Synopsis

Return the independent variable array of a data set

Syntax

get_indep( [id, bkg_id] )

Description

The get_indep() function returns the independent variable array of a 1- or 2-D source or background data set, by data id or bkg_id. For PHA spectra, get_indep() returns the (energ_lo, energ_hi) array, where 'energ_lo' and 'energ_hi' represent the energies at the low and high ends of each bin, respectively. For images, get_indep() returns the (x0, x1) image grid in the current coordinate system.

  • id - the id of the data set to use; if not given, uses the default dataset id (id=1 by default, see "ahelp get_default_id")
  • bkg_id - the id of the background to use, e.g. if more than one background is associated with the data; default is the first background dataset loaded

Example 1

sherpa> get_indep()

When called with no arguments, get_indep() returns the independent variable array of the default data set. In this example, data set 1 is a PHA spectrum.

sherpa> print(get_data())
name           = simple.pi
channel        = Float64[1024]
counts         = Float64[1024]
staterror      = None
syserror       = None
bin_lo         = None
bin_hi         = None
grouping       = None
quality        = None
exposure       = 56494.4943719
backscal       = 9.36267570731e-05
areascal       = 1.0
grouped        = False
subtracted     = False
units          = energy
response_ids   = [1]
background_ids = [1]

sherpa> get_indep()
(array([  0.30000001,   0.31      ,   0.31999999,   0.33000001,
         0.34      ,   0.34999999,   0.36000001,   0.37      ,
. . . .  10.93999958,  10.94999981,  10.96000004,  10.97000027,
        10.97999954,  10.98999977]),
 array([  0.31      ,   0.31999999,   0.33000001,   0.34      ,
         0.34999999,   0.36000001,   0.37      ,   0.38      ,
         0.38999999,   0.40000001,   0.41      ,   0.41999999,
. . . . 10.94999981,  10.96000004,  10.97000027,  10.97999954,
        10.98999977,  11.        ]))

Example 2

sherpa> get_indep(1, bkg_id=1)

To return the independent variable array of a background associated with a data set, the background ID must be specified along with the data set ID. Here, the first background loaded for data set 1 is returned by get_indep().

sherpa> get_indep(1, 1)
           
(array([  0.30000001,   0.31      ,   0.31999999,   0.33000001,
         0.34      ,   0.34999999,   0.36000001,   0.37      ,
. . . .  10.93999958,  10.94999981,  10.96000004,  10.97000027,
        10.97999954,  10.98999977]),
 array([  0.31      ,   0.31999999,   0.33000001,   0.34      ,
         0.34999999,   0.36000001,   0.37      ,   0.38      ,
         0.38999999,   0.40000001,   0.41      ,   0.41999999,
. . . . 10.94999981,  10.96000004,  10.97000027,  10.97999954,
        10.98999977,  11.        ]))

Bugs

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

See Also

confidence
get_conf, get_covar, get_int_proj, get_int_unc, get_proj, get_reg_proj, get_reg_unc
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_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
Smithsonian Institute Smithsonian Institute

The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email:   cxchelp@head.cfa.harvard.edu Smithsonian Institution, Copyright © 1998-2017. All rights reserved.