Last modified: December 2020

URL: https://cxc.cfa.harvard.edu/sherpa/ahelp/dataspace1d.html
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AHELP for CIAO 4.13 Sherpa v1

dataspace1d

Context: data

Synopsis

Create the independent axis for a 1D data set.

Syntax

dataspace1d(start, stop, step=1, numbins=None, id=None, bkg_id=None,
dstype=Data1DInt)

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

Description

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.


Examples

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:

>>> dataspace1d(0.01, 11, 0.01, id='jet', dstype=DataPHA)
>>> dataspace1d(0.01, 11, 0.01, id='jet', bkg_id=1,
...             dstype=DataPHA)

PARAMETERS

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` .

Notes

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


Bugs

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

See Also

data
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
filtering
get_filter, load_filter, set_filter
info
get_default_id, list_bkg_ids, list_data_ids, list_response_ids
modeling
add_model, add_user_pars, clean, load_table_model, load_template_interpolator, load_template_model, load_user_model, save_model, save_source
plotting
plot_data, set_xlinear, set_xlog, set_ylinear, set_ylog
saving
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
statistics
load_user_stat
utilities
calc_data_sum, calc_data_sum2d, calc_ftest, calc_kcorr, calc_mlr, calc_model_sum2d, calc_source_sum2d, get_rate
visualization
contour, contour_data, contour_ratio, histogram1d, histogram2d, image_data, rebin