Last modified: December 2023

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AHELP for CIAO 4.16 Sherpa


Context: data


Create the independent axis for a 1D data set.


dataspace1d(start, stop, step=1, numbins=None, id=None, bkg_id=None,

start - number
stop - number
step - number, optional
numbins - int, optional
id - int or str, optional
bkg_id - int or str, optional
dstype - data class to use, optional


Create an "empty" one-dimensional data set by defining the grid on which the points are defined (the independent axis). The values are set to 0.


Example 1

Create a binned data set, starting at 1 and with a bin-width of 1.

>>> dataspace1d(1, 5, 1)
>>> print(get_indep())
(array([ 1.,  2.,  3.,  4.]), array([ 2.,  3.,  4.,  5.]))

Example 2

This time for an un-binned data set:

>>> dataspace1d(1, 5, 1, dstype=Data1D)
>>> print(get_indep())
(array([ 1.,  2.,  3.,  4.,  5.]),)

Example 3

Specify the number of bins rather than the grid spacing:

>>> dataspace1d(1, 5, numbins=5, id=2)
>>> (xlo, xhi) = get_indep(2)
>>> xlo
array([ 1. ,  1.8,  2.6,  3.4,  4.2])
>>> xhi
array([ 1.8,  2.6,  3.4,  4.2,  5. ])

Example 4

>>> dataspace1d(1, 5, numbins=5, id=3, dstype=Data1D)
>>> (x, ) = get_indep(3)
>>> x
array([ 1.,  2.,  3.,  4.,  5.])

Example 5

Create a grid for a PHA data set called 'jet', and for its background component (note that the axis values are in channels, and there are 1024 channels set):

>>> dataspace1d(1, 1024, id='jet', dstype=DataPHA)
>>> dataspace1d(1, 1024, id='jet', bkg_id=1, dstype=DataPHA)


The parameters for this function are:

Parameter Definition
start The minimum value of the axis.
stop The maximum value of the axis.
step The separation between each grid point. This is not used if numbins is set.
numbins The number of grid points. This over-rides the step setting.
id The identifier for the data set to use. If not given then the default identifier is used, as returned by `get_default_id` .
bkg_id If set, the grid is for the background component of the data set.
dstype What type of data is to be used. Supported values include `Data1DInt` (the default), `Data1D` , and `DataPHA` .


The meaning of the stop parameter depends on whether it is a binned or unbinned data set (as set by the dstype parameter).


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

See Also

copy_data, dataspace2d, datastack, delete_data, fake, get_axes, get_bkg_chisqr_plot, get_bkg_delchi_plot, get_bkg_fit_plot, get_bkg_model_plot, get_bkg_plot, get_bkg_ratio_plot, get_bkg_resid_plot, get_bkg_source_plot, get_counts, get_data, get_data_contour, get_data_contour_prefs, get_data_image, get_data_plot, get_data_plot_prefs, get_dep, get_dims, get_error, get_quality, get_specresp, get_staterror, get_syserror, group, group_adapt, group_adapt_snr, group_bins, group_counts, group_snr, group_width, load_arf, load_arrays, load_ascii, load_bkg, load_bkg_arf, load_bkg_rmf, load_data, load_grouping, load_image, load_multi_arfs, load_multi_rmfs, load_pha, load_quality, load_rmf, load_staterror, load_syserror, load_table, pack_image, pack_pha, pack_table, set_data, set_dep, set_quality, ungroup, unpack_arf, unpack_arrays, unpack_ascii, unpack_bkg, unpack_data, unpack_image, unpack_pha, unpack_rmf, unpack_table
get_filter, load_filter, set_filter
get_default_id, list_bkg_ids, list_data_ids, list_response_ids
add_model, add_user_pars, clean, load_table_model, load_template_interpolator, load_template_model, load_user_model, save_model, save_source
plot_data, set_xlinear, set_xlog, set_ylinear, set_ylog
save_arrays, save_data, save_delchi, save_error, save_filter, save_grouping, save_image, save_pha, save_quality, save_resid, save_staterror, save_syserror, save_table
calc_data_sum, calc_data_sum2d, calc_ftest, calc_kcorr, calc_mlr, calc_model_sum2d, calc_source_sum2d, get_rate
contour, contour_data, contour_ratio, histogram1d, histogram2d, image_data, rebin