Synopsis
Unpack a FITS binary file into a data structure.
Syntax
unpack_table(filename, ncols=2, colkeys=None, dstype=Data1D) ncols - int, optional colkeys - array of str, optional dstype - optional
Examples
Example 1
Read in the first two columns of the file, as the independent (X) and dependent (Y) columns of a data set:
>>> d = unpack_table('sources.fits')Example 2
Read in the first three columns (the third column is taken to be the error on the dependent variable):
>>> d = unpack_table('sources.fits', ncols=3)Example 3
Read in from columns 'RMID' and 'SUR_BRI':
>>> d = unpack_table('rprof.fits', colkeys=['RMID', 'SUR_BRI'])Example 4
The first three columns are taken to be the two independent axes of a two-dimensional data set ( x0 and x1 ) and the dependent value ( y ):
>>> d = unpack_table('fields.fits', ncols=3,
... dstype=sherpa.astro.data.Data2D)Example 5
When using the Crates I/O library, the file name can include CIAO Data Model syntax, such as column selection. This can also be done using the `colkeys` parameter, as shown above:
>>> d = unpack_table('rprof.fits[cols rmid,sur_bri,sur_bri_err]',
... ncols=3)PARAMETERS
The parameters for this function are:
| Parameter | Definition |
|---|---|
| filename | Identify the file to read: a file name, or a data structure representing the data to use, as used by the I/O backend in use by Sherpa: a tablecrate for crates, as used by CIAO, or a list of AstroPy HDU objects. |
| ncols | The number of columns to read in (the first `ncols` columns in the file). The meaning of the columns is determined by the `dstype` parameter. |
| colkeys | An array of the column name to read in. The default is none . |
| dstype | The data class to use. The default is `Data1D` and it is expected to be derived from `sherpa.data.BaseData` . |
Return value
The return value from this function is:
The class of the returned object is controlled 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
- dataspace1d, dataspace2d, datastack, fake, 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, unpack_arf, unpack_arrays, unpack_ascii, unpack_bkg, unpack_data, unpack_image, unpack_pha, unpack_rmf
- filtering
- load_filter
- info
- get_default_id, list_bkg_ids, list_data_ids
- modeling
- add_model, add_user_pars, load_table_model, load_template_interpolator, load_template_model, load_user_model, save_model, save_source
- 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