get_axes

Synopsis

Return information about the independent axes of a data set.

get_axes(id=None, bkg_id=None)

Description

This function returns the coordinates of each point, or pixel, in the data set. The `get_indep` function may be be preferred in some situations.

Examples

Example 1

For 1D data sets, the "alternate" view is the same as the independent axis:

>>> load_arrays(1, [10, 15, 19], [4, 5, 9], Data1D)
>>> get_indep()
array([10, 15, 19])
>>> get_axes()
array([10, 15, 19])

Example 2

For a PHA data set, the approximate energy grid of the channels is returned (this is determined by the EBOUNDS extension of the RMF).

>>> load_pha('core', 'src.pi')
read ARF file src.arf
read RMF file src.rmf
read background file src_bkg.pi
>>> (chans,) = get_indep()
>>> (elo, ehi) = get_axes()
>>> chans[0:5]
array([ 1.,  2.,  3.,  4.,  5.])
>>> elo[0:5]
array([ 0.0073,  0.0146,  0.0292,  0.0438,  0.0584])
>>> ehi[0:5]
array([ 0.0146,  0.0292,  0.0438,  0.0584,  0.073 ])

Example 3

The image has 101 columns by 108 rows. The `get_indep` function returns one-dimensional arrays, for the full dataset, whereas `get_axes` returns values for the individual axis:

>>> load_image('img', 'img.fits')
>>> get_data('img').shape
(108, 101)
>>> set_coord('img', 'physical')
>>> (x0, x1) = get_indep('img')
>>> (a0, a1) = get_axes('img')
>>> (x0.size, x1.size)
(10908, 10908)
>>> (a0.size, a1.size)
(101, 108)
>>> np.all(x0[:101] == a0)
True
>>> np.all(x1[::101] == a1)
True

PARAMETERS

The parameters for this function are:

Return value

The return value from this function is:

axis -- The independent axis values. The differences to `get_dep` that this represents the "alternate grid" for the axis. For PHA data, this is the energy grid (E_MIN and E_MAX). For image data it is an array for each axis, of the length of the axis, using the current coordinate system for the data set.

Bugs

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

See Also

confidence

get_conf, get_conf_results, get_covar, get_covar_opt, get_covar_results, get_covariance_results, get_int_proj, get_int_unc, get_proj, get_proj_opt, get_proj_results, get_projection_results, get_reg_proj, get_reg_unc

contrib

get_chart_spectrum, get_marx_spectrum

data

copy_data, dataspace1d, dataspace2d, datastack, delete_data, fake, get_areascal, get_arf, get_arf_plot, get_backscal, get_bkg, get_bkg_arf, get_bkg_chisqr_plot, get_bkg_delchi_plot, get_bkg_fit_plot, get_bkg_model, get_bkg_model_plot, get_bkg_plot, get_bkg_ratio_plot, get_bkg_resid_plot, get_bkg_rmf, get_bkg_scale, get_bkg_source, get_bkg_source_plot, get_coord, 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_exposure, get_grouping, get_indep, get_quality, get_rmf, get_specresp, get_staterror, get_syserror, group, group_adapt, group_adapt_snr, group_bins, group_counts, group_snr, group_width, load_ascii, load_data, load_grouping, load_quality, set_data, set_quality, ungroup, unpack_ascii, unpack_data

filtering

get_filter, load_filter, set_filter

fitting

calc_stat_info, get_stat_info

info

get_default_id, list_data_ids, list_response_ids, list_stats

methods

get_draws, get_iter_method_name, get_iter_method_opt, get_method, get_method_name, get_method_opt

modeling

clean, get_model, get_model_component, get_model_component_image, get_model_component_plot, get_model_plot, get_num_par, get_num_par_frozen, get_num_par_thawed, get_order_plot, get_par, get_pileup_model, get_response, get_source, get_source_component_image, get_source_component_plot, get_source_contour, get_source_image, get_source_plot, image_source

plotting

get_split_plot, plot_data, set_xlinear, set_xlog, set_ylinear, set_ylog

psfs

get_psf, get_psf_contour, get_psf_image, get_psf_plot

saving

save_error, save_filter, save_grouping, save_quality, save_staterror, save_syserror

statistics

get_chisqr_plot, get_delchi_plot, get_prior, get_sampler, get_stat, get_stat_name

utilities

calc_data_sum, calc_data_sum2d, calc_ftest, calc_kcorr, calc_mlr, calc_model_sum2d, calc_source_sum2d, get_analysis, get_rate

visualization

contour, contour_data, contour_ratio, histogram1d, histogram2d, image_data, image_getregion, rebin