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from __future__ import division # confidence high
from pytools import parseinput, fileutil
import pyfits
import pywcs
import numpy as np
import string
def restoreWCS(fnames, wcskey, clobber=False):
"""
Purpose
=======
Reads in a WCS defined with wcskey and saves it as the primary WCS.
If clobber is False, writes out new files whose names are the original
names with an attached 3 character string representing _'WCSKEY'_.
Otherwise overwrites the files. The WCS is restored from the 'SCI'
extension but the primary WCS of all extensions are updated.
WCS keywords:
'CD1_1', 'CD1_2', 'CD2_1', 'CD2_2',
'CRVAL*',
'CTYPE*',
'CRPIX*',
'CDELT*',
'CUNIT*',
'ORIENTAT' - ?
'TDDALPHA', 'TDDBETA'
'A_x_x', B_x_x' - SIP coefficients
'CPERROR*', 'CPDIS*', 'DP*',
`fnames`: a python list of file names, a string of comma separated file names,
an @file
`wcskey`: a charater
Used for one of 26 alternate WCS definitions.
`clobber`: boolean
A flag to define if the original files should be overwritten
"""
files = parseinput.parseinput(fnames)[0]
for f in files:
isfits, ftype = fileutil.isFits(f)
if not isfits or (isfits and ftype == 'waiver'):
print "RestoreWCS works only with true fits files."
return
else:
if clobber:
print 'Overwriting original files\n'
fobj = pyfits.open(f, mode='update')
name = f
else:
fobj = pyfits.open(f)
name = (f.split('.fits')[0] + '_%s_' + '.fits') %wcskey
for e in range(len(fobj)):
try:
extname = fobj[e].header['EXTNAME'].lower()
except KeyError:
continue
#Restore always from a 'SCI' extension but write it out to 'ERR' and 'DQ'
if extname == 'sci':
sciver = fobj[e].header['extver']
try:
nwcs = pywcs.WCS(fobj[e].header, fobj=fobj, key=wcskey)
except:
print 'utils.restoreWCS: Could not read WCS with key %s in file %s, \
extension %d' % (wcskey, f, e)
return #raise
hwcs = nwcs.to_header()
if nwcs.wcs.has_pc():
for c in ['1_1', '1_2', '2_1', '2_2']:
del hwcs['CD'+c+wcskey]
elif nwcs.wcs.has_cd():
for c in ['1_1', '1_2', '2_1', '2_2']:
hwcs.update(key='CD'+c+wcskey, value=hwcs['PC'+c+wcskey])
del hwcs['PC'+c]
for k in hwcs.keys():
key = k[:-1]
if key in fobj[e].header.keys():
fobj[e].header.update(key=key, value = hwcs[k])
else:
continue
if wcskey == 'O' and fobj[e].header.has_key('TDDALPHA'):
fobj[e].header['TDDALPHA'] = 0.0
fobj[e].header['TDDBETA'] = 0.0
if fobj[e].header.has_key('ORIENTAT'):
cd12 = 'CD1_2%s' % wcskey
cd22 = 'CD2_2%s' % wcskey
norient = np.rad2deg(np.arctan2(hwcs[cd12],hwcs[cd22]))
fobj[e].header.update(key='ORIENTAT', value=norient)
elif extname in ['err', 'dq', 'sdq']:
cextver = fobj[e].header['extver']
if cextver == sciver:
for k in hwcs.keys():
key = k[:-1]
fobj[e].header.update(key=key, value = hwcs[k])
if fobj[e].header.has_key('ORIENTAT'):
cd12 = 'CD1_2%s' % wcskey
cd22 = 'CD2_2%s' % wcskey
norient = np.rad2deg(np.arctan2(hwcs[cd12],hwcs[cd22]))
fobj[e].header.update(key='ORIENTAT', value=norient)
else:
continue
if not clobber:
fobj.writeto(name)
fobj.close()
def archiveWCS(fname, ext, wcskey, wcsname=" ", clobber=False):
"""
Copy the primary WCS to an alternate WCS
with wcskey and name WCSNAME.
"""
assert len(wcskey) == 1
if wcskey == " " and clobber==False:
print "Please provide a valid wcskey for this WCS."
print 'Use "utils.next_wcskey" to obtain a valid wcskey.'
print 'Or use utils.restoreWCS a specific WCS to the primary WCS.'
print 'WCS was NOT archived.'
return
if (wcskey not in available_wcskeys(pyfits.getheader(fname, ext=ext))) and clobber==False:
print 'Wcskey %s is already used in this header.' % wcskey
print 'Use "utils.next_wcskey" to obtain a valid wcskey'
print 'or use "clobber=True" to overwrite the values.'
return
f = pyfits.open(fname, mode='update')
w = pywcs.WCS(f[ext].header, fobj=f)
hwcs = w.to_header()
wkey = 'WCSNAME' + wcskey
f[ext].header.update(key=wkey, value=wcsname)
if w.wcs.has_pc():
for c in ['CD1_1', 'CD1_2', 'CD2_1', 'CD2_2']:
del hwcs[c]
elif w.wcs.has_cd():
for c in ['1_1', '1_2', '2_1', '2_2']:
hwcs.update(key='CD'+c, value=hwcs['PC'+c])
del hwcs['PC'+c]
for k in hwcs.keys():
key = k+wcskey
f[ext].header.update(key=key, value = hwcs[k])
norient = np.rad2deg(np.arctan2(hwcs['CD1_2'],hwcs['CD2_2']))
okey = 'ORIENT%s' % wcskey
f[ext].header.update(key=okey, value=norient)
f.close()
def diff_angles(a,b):
"""
Perform angle subtraction a-b taking into account
small-angle differences across 360degree line.
"""
diff = a - b
if diff > 180.0:
diff -= 360.0
if diff < -180.0:
diff += 360.0
return diff
def getBinning(fobj, extver=1):
# Return the binning factor
binned = 1
if fobj[0].header['INSTRUME'] == 'WFPC2':
mode = fobj[0].header.get('MODE', "")
if mode == 'AREA': binned = 2
else:
binned = fobj['SCI', extver].header.get('BINAXIS',1)
return binned
def wcsnames(header):
"""
Purpose
=======
Return a dictionary of wcskey: WCSNAME pairs
"""
names = header["WCSNAME*"]
d = {}
for c in names:
d[c.key[-1]] = c.value
return d
def wcskeys(header):
"""
Purpose
=======
Returns a list of characters used in the header for alternate
WCS description via WCSNAME keyword
`header`: pyfits.Header
"""
names = header["WCSNAME*"]
return [key.split('WCSNAME')[1] for key in names.keys()]
def available_wcskeys(header):
"""
Purpose
=======
Returns a list of characters which are not used in the header
with WCSNAME keyword. Any of them can be used to save a new
WCS.
`header`: pyfits.Header
"""
all_keys = list(string.ascii_uppercase)
used_keys = wcskeys(header)
try:
used_keys.remove("")
except ValueError:
pass
[all_keys.remove(key) for key in used_keys]
return all_keys
def next_wcskey(header):
"""
Purpose
=======
Returns next available character to be used for an alternate WCS
`header`: pyfits.Header
"""
allkeys = available_wcskeys(header)
if allkeys != []:
return allkeys[0]
else:
return None
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