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Last modified: December 2010

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AHELP for CIAO 4.3 Sherpa v1


Context: data


Load 1D data from a file


load_data( [id], filename, [options] )


The load_data command is a filetype-independent method of loading 1D data from a file (e.g. if the file-specific load command is unknown or if the filetype is unknown). It tries to load the file in the following order: load_pha, load_table, and load_ascii.

  • id - the id of the dataset to use; if not given, uses the default dataset id (id=1 by default, see "ahelp get_default_id")
  • filename - the name of the file (with path) which contains the data

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

  • load_pha: use_errors
  • load_table: ncols, colkeys, and dstype
  • load_ascii: ncols, colkeys, sep, comment, and dstype

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

Example 1

sherpa> load_data("data.filtered")

Using the default settings, load a data file into Sherpa.

Example 2

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

Load the first three columns of data.txt, using the dataset id "src". This example could also have been done using the load_ascii command.

Example 3

sherpa> load_data("src", "source.pha")

Data is loaded from the file source.pha with data id "src". This example could also have been done using the load_pha command.

Example 4

sherpa> load_data("rprofile_mid.fits[cols RMID,SUR_BRI,SUR_BRI_ERR]")
sherpa> load_data("rprofile_mid.fits",

These commands are equivalent ways of loading x=RMID, y=SUR_BRI, and staterror=SUR_BRI_ERR from 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 load_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_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_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_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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