astropy.io.fits.diff:HeaderDiff.__init__

Parameters

a : `~astropy.io.fits.Header` or string or bytes

A header.

b : `~astropy.io.fits.Header` or string or bytes

A header to compare to the first header.

ignore_keywords : sequence, optional

Header keywords to ignore when comparing two headers; the presence of these keywords and their values are ignored. Wildcard strings may also be included in the list.

ignore_comments : sequence, optional

A list of header keywords whose comments should be ignored in the comparison. May contain wildcard strings as with ignore_keywords.

numdiffs : int, optional

The number of pixel/table values to output when reporting HDU data differences. Though the count of differences is the same either way, this allows controlling the number of different values that are kept in memory or output. If a negative value is given, then numdiffs is treated as unlimited (default: 10).

rtol : float, optional

The relative difference to allow when comparing two float values either in header values, image arrays, or table columns (default: 0.0). Values which satisfy the expression

$$\left|a-b\right|>\text{atol}+\text{rtol}\cdot \left|b\right|$$

are considered to be different. The underlying function used for comparison is numpy.allclose.

atol : float, optional

The allowed absolute difference. See also rtol parameter.

ignore_blanks : bool, optional

Ignore extra whitespace at the end of string values either in headers or data. Extra leading whitespace is not ignored (default: True).

ignore_blank_cards : bool, optional

Ignore all cards that are blank, i.e. they only contain whitespace (default: True).