calc_source_sum2d

sherpa.astro.ui.calc_source_sum2d(reg=None, id=None)

Sum up the fitted model for a 2D data set.

Parameters:

• reg (str, optional) – The spatial filter to use. The default, None, is to use the whole data set.
• id (int or str, optional) – Use the source expression associated with this data set. If not given then the default identifier is used, as returned by get_default_id.

Returns:

msum – The sum of the model values that lie within the given region. This does not include any PSF included by set_psf.

Return type:

number

See also

calc_model_sum2d()

Sum up the fitted model for a 2D data set.

calc_source_sum()

Sum up the model over a pass band.

set_psf()

Add a PSF model to a data set.

set_model()

Set the source model expression for a data set.

Notes

The coordinate system of the region filter is determined by the coordinate setting for the data set (e.g. get_coord).

Any existing filter on the data set - e.g. as created by ignore2d or notice2d - is ignored by this function.

Examples

The following examples use the data in the default data set created with the following calls, which sets the y (data) values to be 0 to 11 in a 3 row by 4 column image:

>>> ivals = np.arange(12)
>>> (y,x) = np.mgrid[0:3, 0:4]
>>> y = y.flatten()
>>> x = x.flatten()
>>> load_arrays(1, x, y, ivals, (3,4), DataIMG)
>>> set_source(const2d.bgnd)
>>> bgnd.c0 = 2

With no argument, the full data set is used. Since the model evaluates to 2 per pixel, and there are 12 pixels in the data set, the result is 24:

>>> calc_source_sum2d()
24.0

Only use pixels that fall within the given spatial filters:

>>> calc_source_sum2d('circle(2,2,1)')
8.0
>>> calc_source_sum2d('field()-circle(2,2,1)')
16.0