req_cards(self, keyword, pos, test, fix_value, option, errlist)
If pos=None
, the card can be anywhere in the header. If the card does not exist, the new card will have the fix_value
as its value when created. Also check the card's value by using the test
argument.
The keyword to validate
If an int
, this specifies the exact location this card should have in the header. Remember that Python is zero-indexed, so this means pos=0
requires the card to be the first card in the header. If given a callable, it should take one argument--the actual position of the keyword--and return :None:None:`True` or :None:None:`False`. This can be used for custom evaluation. For example if pos=lambda idx: idx > 10
this will check that the keyword's index is greater than 10.
This should be a callable (generally a function) that is passed the value of the given keyword and returns :None:None:`True` or :None:None:`False`. This can be used to validate the value associated with the given keyword.
A valid value for a FITS keyword to to use if the given test
fails to replace an invalid value. In other words, this provides a default value to use as a replacement if the keyword's current value is invalid. If :None:None:`None`, there is no replacement value and the keyword is unfixable.
Output verification option. Must be one of "fix"
, "silentfix"
, "ignore"
, "warn"
, or "exception"
. May also be any combination of "fix"
or "silentfix"
with "+ignore"
, +warn
, or +exception"
(e.g. ``"fix+warn"
). See astropy:verify
for more info.
A list of validation errors already found in the FITS file; this is used primarily for the validation system to collect errors across multiple HDUs and multiple calls to req_cards
.
Check the existence, location, and value of a required Card
.
The following pages refer to to this document either explicitly or contain code examples using this.
astropy.io.fits.hdu.base._ValidHDU.req_cards
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