Last modified: December 2023

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AHELP for CIAO 4.16 Sherpa


Context: data


Unpack an ASCII file into a data structure.


unpack_ascii(filename, ncols=2, colkeys=None, dstype=Data1D, sep=' ',

filename - str
ncols - int, optional
colkeys - array of str, optional
sep - str, optional
comment - str, optional
dstype - optional


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_ascii('sources.dat')

Example 2

Read in the first three columns (the third column is taken to be the error on the dependent variable):

>>> d = unpack_ascii('sources.dat', ncols=3)

Example 3

Read in from columns 'col2' and 'col3':

>>> d = unpack_ascii('tbl.dat', colkeys=['col2', 'col3'])

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_ascii('fields.dat', ncols=3,
...                  dstype=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_ascii('tbl.dat[cols rmid,sur_bri,sur_bri_err]',
...                  ncols=3)


The parameters for this function are:

Parameter Definition
filename The name of the file to read in. Selection of the relevant column depends on the I/O library in use (Crates or AstroPy).
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 .
sep The separator character. The default is ' ' .
comment The comment character. The default is '#' .
dstype The data class to use. The default is `Data1D` and it is expected to be derived from `` .

Return value

The return value from this function is:

The type of the returned object is controlled by the `dstype` parameter.


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

See Also

copy_data, dataspace1d, 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_quality, ungroup, unpack_arf, unpack_arrays, unpack_bkg, unpack_data, unpack_image, unpack_pha, unpack_rmf, unpack_table
get_filter, load_filter, set_filter
get_default_id, list_bkg_ids, list_data_ids, list_response_ids
add_model, add_user_pars, clean, load_table_model, load_template_interpolator, load_template_model, load_user_model, save_model, save_source
plot_data, set_xlinear, set_xlog, set_ylinear, set_ylog
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
calc_data_sum, calc_data_sum2d, calc_ftest, calc_kcorr, calc_mlr, calc_model_sum2d, calc_source_sum2d, get_rate
contour, contour_data, contour_ratio, histogram1d, histogram2d, image_data, rebin