unpack_ascii

sherpa.astro.ui.unpack_ascii(filename, ncols=2, colkeys=None, dstype=<class 'sherpa.data.Data1D'>, sep=' ', comment='#')

Unpack an ASCII file into a data structure.

Parameters:

filenamestr

The name of the file to read in. Selection of the relevant column depends on the I/O library in use (Crates or AstroPy).

ncolsint, optional

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.

colkeysarray of str, optional

An array of the column name to read in. The default is None.

sepstr, optional

The separator character. The default is ' '.

commentstr, optional

The comment character. The default is '#'.

dstypeoptional

The data class to use. The default is Data1D and it is expected to be derived from sherpa.data.BaseData.

Returns:

instance

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

See also

load_ascii

Load an ASCII file as a data set.

set_data

Set a data set.

unpack_table

Unpack a FITS binary file into a data structure.

Examples

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')

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)

Read in from columns ‘col2’ and ‘col3’:

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

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)

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)