diff options
| -rw-r--r-- | acispy/header.py | 34 |
1 files changed, 31 insertions, 3 deletions
diff --git a/acispy/header.py b/acispy/header.py index 0614cd6..6aa0ead 100644 --- a/acispy/header.py +++ b/acispy/header.py @@ -3,16 +3,25 @@ """ Manipulate the FITS header keywords using CIAO tools -``dmkeypar`` and ``dmhedit``. +``dmkeypar`` and ``dmhedit``, as well as ``astropy.io.fits``. """ import subprocess +from astropy.io import fits + def read_keyword(infile, keyword): """ - Read the specified header keyword, and return a dictionary - with its value, unit, data type, and comment. + Read the specified header keyword using CIAO tool ``dmkeypar``, + and return a dictionary with its value, unit, data type, and comment. + + NOTE + ---- + The ``dmkeypar`` tool cannot read some raw/reserved keywords in FITS + header, e.g., ``BUNIT``. These raw header keywords can be obtained + using ``dmlist <infile> opt=header,raw``, or using the following + ``read_keyword2()``. """ DATATYPES = { "real": float, @@ -41,6 +50,25 @@ def read_keyword(infile, keyword): "unit": unit, "comment": comment} +def read_keyword2(infile, keyword): + """ + Read the specified header keyword using ``astropy.io.fits`` + and return a tuple of ``(value, comment)``. + + NOTE + ---- + Header of all extensions (a.k.a. blocks) are combined to locate + the keyword. + """ + with fits.open(infile) as f: + h = fits.header.Header() + for hdu in f: + h.extend(hdu.header) + value = h[keyword] + comment = h.comments[keyword] + return (value, comment) + + def write_keyword(infile, keyword, value, datatype=None, unit=None, comment=None): """ |