def read_projection_from_fits(fitsfile, extname=None):
"""
Load a WCS or HPX projection.
"""
f = fits.open(fitsfile)
nhdu = len(f)
# Try and get the energy bounds
try:
ebins = find_and_read_ebins(f)
except:
ebins = None
if extname is None:
# If there is an image in the Primary HDU we can return a WCS-based
# projection
if f[0].header['NAXIS'] != 0:
proj = WCS(f[0].header)
return proj, f, f[0]
else:
if f[extname].header['XTENSION'] == 'IMAGE':
proj = WCS(f[extname].header)
return proj, f, f[extname]
elif extname in ['SKYMAP', 'SKYMAP2']:
proj = HPX.create_from_hdu(f[extname], ebins)
return proj, f, f[extname]
elif f[extname].header['XTENSION'] == 'BINTABLE':
try:
if f[extname].header['PIXTYPE'] == 'HEALPIX':
proj = HPX.create_from_hdu(f[extname], ebins)
return proj, f, f[extname]
except:
pass
return None, f, None
# Loop on HDU and look for either an image or a table with HEALPix data
for i in range(1, nhdu):
# if there is an image we can return a WCS-based projection
if f[i].header['XTENSION'] == 'IMAGE':
proj = WCS(f[i].header)
return proj, f, f[i]
elif f[i].header['XTENSION'] == 'BINTABLE':
if f[i].name in ['SKYMAP', 'SKYMAP2']:
proj = HPX.create_from_hdu(f[i], ebins)
return proj, f, f[i]
try:
if f[i].header['PIXTYPE'] == 'HEALPIX':
proj = HPX.create_from_hdu(f[i], ebins)
return proj, f, f[i]
except:
pass
return None, f, None
def create_from_hdu(cls, hdu, ebins):
""" Creates and returns an HpxMap object from a FITS HDU.
hdu : The FITS
ebins : Energy bin edges [optional]
"""
hpx = HPX.create_from_hdu(hdu, ebins)
colnames = hdu.columns.names
cnames = []
if hpx.conv.convname == 'FGST_SRCMAP_SPARSE':
pixs = hdu.data.field('PIX')
chans = hdu.data.field('CHANNEL')
keys = chans * hpx.npix + pixs
vals = hdu.data.field('VALUE')
nebin = len(ebins)
data = np.zeros((nebin, hpx.npix))
data.flat[keys] = vals
else:
for c in colnames:
if c.find(hpx.conv.colstring) == 0:
cnames.append(c)
nebin = len(cnames)
data = np.ndarray((nebin, hpx.npix))
for i, cname in enumerate(cnames):
data[i, 0:] = hdu.data.field(cname)
return cls(data, hpx)
def create_from_hdu(cls, hdu, ebins):
""" Creates and returns an HpxMap object from a FITS HDU.
hdu : The FITS
ebins : Energy bin edges [optional]
"""
hpx = HPX.create_from_hdu(hdu, ebins)
colnames = hdu.columns.names
cnames = []
if hpx.conv.convname == 'FGST_SRCMAP_SPARSE':
pixs = hdu.data.field('PIX')
chans = hdu.data.field('CHANNEL')
keys = chans * hpx.npix + pixs
vals = hdu.data.field('VALUE')
nebin = len(ebins)
data = np.zeros((nebin, hpx.npix))
data.flat[keys] = vals
else:
for c in colnames:
if c.find(hpx.conv.colstring) == 0:
cnames.append(c)
nebin = len(cnames)
data = np.ndarray((nebin, hpx.npix))
for i, cname in enumerate(cnames):
data[i, 0:] = hdu.data.field(cname)
return cls(data, hpx)