dataspace1d

sherpa.astro.ui.dataspace1d(start, stop, step=1, numbins=None, id: Optional[IdType] = None, bkg_id: Optional[IdType] = None, dstype=<class 'sherpa.data.Data1DInt'>) → None

Create the independent axis for a 1D data set.

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

Changed in version 4.17.1: When creating a DataPHA data set, the start and stop values are now used, and the step and numbins arguments must be meaningful (if set). Previously it always started the channel values at 1.

Parameters:

  • 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. This is only used when dstype is set to DataPHA.

  • dstype (data class to use, optional) – What type of data is to be used. Supported values include Data1DInt (the default), Data1D, and DataPHA.

See also

dataspace2d

Create the independent axis for a 2D data set.

get_dep

Return the dependent axis of a data set.

get_indep

Return the independent axes of a data set.

set_dep

Set the dependent axis of a data set.

Notes

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

For DataPHA values, step and numbins should be left at their default values, and only the start and stop values changed.

Examples

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.]))

This time for an un-binned data set:

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

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. ])

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