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# Copyright (c) 2017 Weitian LI <liweitianux@live.com>
# MIT license
"""
Manipulate the FITS header keywords using CIAO tools
``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 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,
"integer": int,
"boolean": bool,
"string": str
}
subprocess.check_call(["punlearn", "dmkeypar"])
subprocess.check_call([
"dmkeypar", "infile=%s" % infile, "keyword=%s" % keyword
])
datatype = subprocess.check_output([
"pget", "dmkeypar", "datatype"
]).decode("utf-8").strip()
value = subprocess.check_output([
"pget", "dmkeypar", "value"
]).decode("utf-8").strip()
value = DATATYPES[datatype](value)
unit = subprocess.check_output([
"pget", "dmkeypar", "unit"
]).decode("utf-8").strip()
comment = subprocess.check_output([
"pget", "dmkeypar", "comment"
]).decode("utf-8").strip()
return {"value": value, "datatype": datatype,
"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):
"""
Write the specified keyword to the file header.
"""
DATATYPES = {
"real": "double",
"integer": "long",
"boolean": "boolean",
"string": "string"
}
subprocess.check_call(["punlearn", "dmhedit"])
cmd = [
"dmhedit", "infile=%s" % infile, "filelist=none",
"operation=add", "key=%s" % keyword, "value=%s" % value
]
if datatype:
cmd += ["datatype=%s" % DATATYPES[datatype]]
if unit:
cmd += ["unit=%s" % unit]
if comment:
cmd += ["comment=%s" % comment]
subprocess.check_call(cmd)
def copy_keyword(infile1, infile2, keyword):
"""
Copy the specified keyword(s) from infile1 to infile2.
"""
if not isinstance(keyword, list):
keyword = [keyword]
for kw in keyword:
data = read_keyword(infile1, kw)
write_keyword(infile2, kw, **data)
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