def _rdhd_special(self, name):
"""Provide read access to special header items of type '?' to _rdhd."""
if name == "freqs":
h = self.haccess(name, "read")
c, o = _miriad.hread(h, 0, "i")
rv = [c]
offset = 8
while True:
try:
c, o = _miriad.hread(h, offset, "i")
rv.append(c)
offset += 8
c, o = _miriad.hread(h, offset, "d")
rv.append(c)
offset += 8
c, o = _miriad.hread(h, offset, "d")
rv.append(c)
offset += 8
except IOError:
break
_miriad.hdaccess(h)
return rv
else:
raise ValueError("Unknown special header: " + name)
def _wrhd(self, name, val):
"""Provide write access to header items via low-level calls."""
item_type = itemtable[name]
if item_type == "?":
return self._wrhd_special(name, val)
h = self.haccess(name, "write")
if len(item_type) == 1:
try:
len(val)
except TypeError:
val = [val]
if item_type == "a":
offset = 0
else:
offset = _miriad.hwrite_init(h, item_type)
for v in val:
offset += _miriad.hwrite(h, offset, v, item_type)
else:
offset = _miriad.hwrite_init(h, "b")
for v, t in zip(val, item_type):
offset += _miriad.hwrite(h, offset, v, t)
_miriad.hdaccess(h)
def _wrhd_special(self, name, val):
"""Provide write access to special header items of type '?' to _wrhd."""
if name == "freqs":
h = self.haccess(name, "write")
_miriad.hwrite(h, 0, val[0], "i")
offset = 8
for i, v in enumerate(val[1:]):
if i % 3 == 0:
_miriad.hwrite(h, offset, v, "i")
else:
_miriad.hwrite(h, offset, v, "d")
offset += 8
_miriad.hdaccess(h)
else:
raise ValueError("Unknown special header: " + name)
def items(self):
"""
Get the list of available header items.
Returns
-------
list of str
list of available header items
"""
items = []
for i in itemtable:
try:
_miriad.hdaccess(self.haccess(i, "read"))
items.append(i)
except IOError:
pass
return items
def _rdhd(self, name):
"""
Provide read access to header items via low-level calls.
Parameters
----------
name : str
name of header item
Returns
-------
str or int or float
value of header item
"""
itype = itemtable[name]
if itype == "?":
return self._rdhd_special(name)
h = self.haccess(name, "read")
rv = []
if len(itype) == 1:
if itype == "a":
offset = 0
else:
t, offset = _miriad.hread_init(h)
assert itype == t
while True:
try:
c, o = _miriad.hread(h, offset, itype)
except IOError:
break
if itype == "a":
try:
c = str(c[:o], "utf-8")
except TypeError:
c = c[:o]
rv.append(c)
offset += o
if itype == "a":
rv = "".join(rv)
else:
t, offset = _miriad.hread_init(h)
assert t == "b"
for t in itype:
v, o = _miriad.hread(h, offset, t)
rv.append(v)
offset += o
_miriad.hdaccess(h)
if len(rv) == 1:
return rv[0]
elif type(rv) == str:
return rv
else:
return np.array(rv)