| .. currentmodule:: astropy.io.fits |
|
|
| Miscellaneous Features |
| ********************** |
|
|
| This section describes some of the miscellaneous features of :mod:`astropy.io.fits`. |
|
|
| .. _io-fits-differs: |
|
|
| Differs |
| ======= |
|
|
| The :mod:`astropy.io.fits.diff` module contains several facilities for |
| generating and reporting the differences between two FITS files, or two |
| components of a FITS file. |
|
|
| The :class:`FITSDiff` class can be used to generate and represent the |
| differences between either two FITS files on disk, or two existing |
| :class:`HDUList` objects (or some combination thereof). |
|
|
| Likewise, the :class:`HeaderDiff` class can be used to find the differences |
| just between two :class:`Header` objects. Other available differs include |
| :class:`HDUDiff`, :class:`ImageDataDiff`, :class:`TableDataDiff`, and |
| :class:`RawDataDiff`. |
|
|
| Each of these classes are instantiated with two instances of the objects that |
| they diff. The returned diff instance has a number of attributes starting with |
| ``.diff_`` that describe differences between the two objects. |
|
|
| For example the :class:`HeaderDiff` class cam be used to find the differences |
| between two :class:`Header` objects like so:: |
|
|
| >>> from astropy.io import fits |
| >>> header1 = fits.Header([('KEY_A', 1), ('KEY_B', 2)]) |
| >>> header2 = fits.Header([('KEY_A', 3), ('KEY_C', 4)]) |
| >>> diff = fits.diff.HeaderDiff(header1, header2) |
| >>> diff.identical |
| False |
| >>> diff.diff_keywords |
| (['KEY_B'], ['KEY_C']) |
| >>> diff.diff_keyword_values |
| defaultdict(..., {'KEY_A': [(1, 3)]}) |
|
|
| See the API documentation for details on the different differ classes. |
|
|
