SmartHDUList¶

class gammapy.utils.fits.SmartHDUList(hdu_list)[source]¶

Bases: object

A FITS HDU list wrapper with some sugar.

This is a thin wrapper around HDUList, with some conveniences built in.

Parameters:

hdu_list : HDUList

HDU list (stored in hdu_list attribute)

Examples

Opening a SmartHDUList calls astropy.io.fits.open to get a HDUList object, and then stores it away in the hdu_list attribute:

>>> from gammapy.utils.fits import SmartHDUList
>>> hdus = SmartHDUList.open('$GAMMAPY_EXTRA/datasets/catalogs/fermi/gll_psch_v08.fit.gz')
>>> type(hdus.hdu_list)
astropy.io.fits.hdu.hdulist.HDUList

So of course, you can do the usual things via hdus.hdu_list:

>>> hdus.hdu_list.filename()
>>> hdus.hdu_list.info()
>>> [hdu.name for hdu in hdus.hdu_list]

In addition, for a SmartHDUList, it’s easier to get the HDUs you want:

>>> hdus.get_hdu('Extended Sources')  # by name
>>> hdus.get_hdu(2)  # by index
>>> hdus.get_hdu(hdu_type='image')  # first image (skip primary if empty)
>>> hdus.get_hdu(hdu_type='table')  # first table

TODO: add more conveniences, e.g. to create HDU lists from lists of Gammapy objects that can be serialised to FITS (e.g. SkyImage, SkyCube, EventList, ...)

Attributes Summary

names List of HDU names (stripped, upper-case).

Methods Summary

`get_hdu`([hdu, hdu_type])	Get HDU with given name, number or type.
`get_hdu_index`([hdu, hdu_type])	Get index of HDU with given name, number or type.
`open`(filename, **kwargs)	Create from FITS file (`SmartHDUList`).
`write`(filename, **kwargs)	Write HDU list to FITS file.

Attributes Documentation

names¶: List of HDU names (stripped, upper-case).

Methods Documentation

get_hdu(hdu=None, hdu_type=None)[source]¶

Get HDU with given name, number or type.

This method simply calls get_hdu_index(hdu, hdu_type), and if successful, returns the HDU for that given index.

get_hdu_index(hdu=None, hdu_type=None)[source]¶

Get index of HDU with given name, number or type.

If hdu is given, tries to find an HDU of that given name or number. Otherwise, if hdu_type is given, looks for the first suitable HDU.

Raises KeyError if no suitable HDU is found.

Parameters:

hdu : int or str

HDU number or name, passed to astropy.io.fits.HDUList.index_of.

hdu_type : {‘primary’, ‘image’ , ‘table’}

Type of HDU to load

Returns:

idx : int

HDU index

classmethod open(filename, **kwargs)[source]¶

Create from FITS file (SmartHDUList).

This calls astropy.io.fits.open, passing **kwargs. It reads the FITS headers, but not the data.

The filename is passed through make_path, which accepts strings or Path objects and does environment variable expansion.

Parameters:

filename : str

Filename

write(filename, **kwargs)[source]¶

Write HDU list to FITS file.

This calls astropy.io.fits.HDUList.writeto, passing **kwargs.

The filename is passed through make_path, which accepts strings or Path objects and does environment variable expansion.

Parameters:

filename : str

Filename

Navigation

SmartHDUList¶