dataspace1d

Context: data

Synopsis

Create the independent axis for a 1D data set.

Syntax

dataspace1d(start, stop, step=1, numbins=None, id: int | str | None =
None, bkg_id: int | str | None = None, dstype=Data1DInt)

No return value.

Description

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.

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. 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` .

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.

Changes in CIAO

Changed in CIAO 4.18

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.

Bugs

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