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Last modified: December 2010

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AHELP for CIAO 4.3 Sherpa v1


Context: data


Unpack a table data, ASCII data, or a spectrum from a crate


unpack_data( filename|crate, [options] )


The unpack_data command unpacks tabular data from a FITS file or a column-based text file into a Sherpa data object. It may also be used to unpack spectral data from a PHA FITS file.

If a filename is provided as input, a crate is created but hidden and cannot be used for other analysis in the session.

  • filename - the name of the file (with path) or crate which contains the data

If the filetype is known, file-specific options may be included in the unpack_data command. They are:

  • unpack_pha: use_errors
  • unpack_table: ncols, colkeys, and dstype
  • unpack_ascii: ncols, colkeys, sep, comment, and dstype

Refer to the individual command ahelp files for specifics on the options.

Example 1

sherpa> filt = unpack_data("data.filtered")

Unpack data from the file "data.filtered", using the default settings.

Example 2

sherpa> src = unpack_data("data.txt", ncols=3)

Unpack the first three columns of data.txt. This example could also have been done using the unpack_ascii command.

Example 3

sherpa> phacr = read_pha("3c273.pha")
sherpa> phadata = unpack_data(phacr)

The spectrum is read into an PHACrate (named "phacr") from the file 3c273.pha. The data is then unpacked into Sherpa from the crate; this example could also have been done using the unpack_pha command.

Example 4

sherpa> rprof = unpack_data("rprofile_mid.fits[cols
sherpa> rprof = unpack_data("rprofile_mid.fits",

These commands are equivalent ways of creating a data object called "rprof" from the RMID, SUR_BRI, and SUR_BRI_ERR columns of rprofile_mid.fits, a radial profile for which the midpoint of the annular regions has been calculated. This example could also have been done using the unpack_table command.


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

See Also

copy_data, dataspace1d, dataspace2d, delete_data, fake, get_axes, get_bkg_plot, get_counts, get_data, get_data_plot, get_dep, get_dims, get_error, get_quality, get_specresp, get_staterror, get_syserror, group_sherpa, 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_ascii, unpack_bkg, 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_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, get_ratio, get_resid, histogram1d, histogram2d, image_data, rebin

Last modified: December 2010
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