get_indep

Context: data

Synopsis

Return the independent variable array of a data set

Syntax

get_indep( [id, bkg_id] )

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.