# Data¶

class sherpa.data.Data(name, indep, y, staterror=None, syserror=None)[source] [edit on github]

Data class for generic, N-Dimensional data sets, where N depends on the number of independent axes passed during initialization.

A data class is the collection of a data space and a number of data arrays for the dependent variable and associated errors.

This class can be extended by classes definining data sets of specific dimensionality. Extending classes should override the _init_data_space method.

This class provides most of the infrastructure for extending classes for free.

Data classes contain a mask attribute, which can be used ignore certain values in the array when fitting or plotting that data. The convention in Sherpa is that True marks a values as valid and False as invalid (note that this is opposite to the numpy convention). When a Data instance is initialized with a dependent array that has a mask attribute (e.g. numpy masked array), it will attempt to convert that mask to the Sherpa convention and raise a warning otherwise. In any case, the user can set data.mask after initialization if that conversion does not yield the expected result.

Attributes Summary

 dep Left for compatibility with older versions indep Return the grid of the data space associated with this data set. mask Mask array for dependent variable

Methods Summary

 apply_filter(data) eval_model(modelfunc) eval_model_to_fit(modelfunc) get_dep([filter]) Return the dependent axis of a data set. Return the dimensions of this data space as a tuple of tuples. get_error([filter, staterrfunc]) Return the total error on the dependent variable. get_indep([filter]) Return the independent axes of a data set. get_staterror([filter, staterrfunc]) Return the statistical error on the dependent axis of a data set. get_syserror([filter]) Return the statistical error on the dependent axis of a data set. get_y([filter, yfunc, use_evaluation_space]) Return dependent axis in N-D view of dependent variable get_yerr([filter, staterrfunc]) Return errors in dependent axis in N-D view of dependent variable get_ylabel([yfunc]) Return label for dependent axis in N-D view of dependent variable” ignore(*args, **kwargs) notice(mins, maxes[, ignore]) set_dep(val) Set the dependent variable values” set_indep(val) to_fit([staterrfunc])

Attributes Documentation

dep

Left for compatibility with older versions

indep

Return the grid of the data space associated with this data set. :returns: :rtype: tuple of array_like

mask

Returns

Return type

bool or numpy.ndarray

Methods Documentation

apply_filter(data)[source] [edit on github]
eval_model(modelfunc)[source] [edit on github]
eval_model_to_fit(modelfunc)[source] [edit on github]
get_dep(filter=False)[source] [edit on github]

Return the dependent axis of a data set.

Parameters

filter (bool, optional) – Should the filter attached to the data set be applied to the return value or not. The default is False.

Returns

axis – The dependent axis values for the data set. This gives the value of each point in the data set.

Return type

array

get_indep()

Return the independent axis of a data set.

get_error()

Return the errors on the dependent axis of a data set.

get_staterror()

Return the statistical errors on the dependent axis of a data set.

get_syserror()

Return the systematic errors on the dependent axis of a data set.

get_dims()[source] [edit on github]

Return the dimensions of this data space as a tuple of tuples. The first element in the tuple is a tuple with the dimensions of the data space, while the second element provides the size of the dependent array. :returns: :rtype: tuple

get_error(filter=False, staterrfunc=None)[source] [edit on github]

Return the total error on the dependent variable.

Parameters
• filter (bool, optional) – Should the filter attached to the data set be applied to the return value or not. The default is False.

• staterrfunc (function) – If no statistical error has been set, the errors will be calculated by applying this function to the dependent axis of the data set.

Returns

axis – The error for each data point, formed by adding the statistical and systematic errors in quadrature.

Return type

array or None

get_dep()

Return the independent axis of a data set.

get_staterror()

Return the statistical errors on the dependent axis of a data set.

get_syserror()

Return the systematic errors on the dependent axis of a data set.

get_indep(filter=False)[source] [edit on github]

Return the independent axes of a data set.

Parameters

filter (bool, optional) – Should the filter attached to the data set be applied to the return value or not. The default is False.

Returns

axis – The independent axis values for the data set. This gives the coordinates of each point in the data set.

Return type

tuple of arrays

get_dep()

Return the dependent axis of a data set.

get_staterror(filter=False, staterrfunc=None)[source] [edit on github]

Return the statistical error on the dependent axis of a data set.

Parameters
• filter (bool, optional) – Should the filter attached to the data set be applied to the return value or not. The default is False.

• staterrfunc (function) – If no statistical error has been set, the errors will be calculated by applying this function to the dependent axis of the data set.

Returns

axis – The statistical error for each data point. A value of None is returned if the data set has no statistical error array and staterrfunc is None.

Return type

array or None

get_error()

Return the errors on the dependent axis of a data set.

get_indep()

Return the independent axis of a data set.

get_syserror()

Return the systematic errors on the dependent axis of a data set.

get_syserror(filter=False)[source] [edit on github]

Return the statistical error on the dependent axis of a data set.

Parameters

filter (bool, optional) – Should the filter attached to the data set be applied to the return value or not. The default is False.

Returns

axis – The systematic error for each data point. A value of None is returned if the data set has no systematic errors.

Return type

array or None

get_error()

Return the errors on the dependent axis of a data set.

get_indep()

Return the independent axis of a data set.

get_staterror()

Return the statistical errors on the dependent axis of a data set.

get_y(filter=False, yfunc=None, use_evaluation_space=False)[source] [edit on github]

Return dependent axis in N-D view of dependent variable

Parameters
• filter

• yfunc

• use_evaluation_space

get_yerr(filter=False, staterrfunc=None)[source] [edit on github]

Return errors in dependent axis in N-D view of dependent variable

Parameters
• filter

• staterrfunc

get_ylabel(yfunc=None)[source] [edit on github]

Return label for dependent axis in N-D view of dependent variable”

Parameters

yfunc

ignore(*args, **kwargs)[source] [edit on github]
notice(mins, maxes, ignore=False)[source] [edit on github]
set_dep(val)[source] [edit on github]

Set the dependent variable values”

Parameters

val

set_indep(val)[source] [edit on github]
to_fit(staterrfunc=None)[source] [edit on github]
to_guess()[source] [edit on github]