Last modified: December 2024

URL: https://cxc.cfa.harvard.edu/sherpa/ahelp/dataspace1d.html
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AHELP for CIAO 4.17 Sherpa

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)

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 (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)

PARAMETERS

The parameters for this function are:

Parameter Type information Definition
start number The minimum value of the axis.
stop number The maximum value of the axis.
step number, optional The separation between each grid point. This is not used if numbins is set.
numbins int, optional The number of grid points. This overrides the step setting.
id int, str, or None, optional 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 int, str, or None, optional If set, the grid is for the background component of the data set.
dstype data class to use, optional 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