def __init__(self, filename):
""" Read the binary GADGET header """
file = open(filename, mode='rb')
header = binary_snapshot_io.read_header(file)
file.close()
self._data = header
del self._data['buffer']
self.num_particles_file = np.sum(self._data['num_particles'])
if self._data['flag_doubleprecision']:
self.dtype = _rtype(float64, self._data['swap_endian'])
else:
self.dtype = _rtype(float32, self._data['swap_endian'])
self.dtype_width = np.dtype(self.dtype).itemsize
#Also find length of id
f = open(filename, mode='rb')
f.seek(256+24 + int(self.num_particles_file) * 6 * int(self.dtype_width))
id_block_len = np.fromfile(f, _rtype(uint32, self._data['swap_endian']), 1)[0]
if id_block_len==4*self.num_particles_file:
self.long_ids = False
self.id_width = 4
self.id_type = _rtype(uint32, self._data['swap_endian'])
elif id_block_len==8*self.num_particles_file:
self.long_ids = True
self.id_width = 8
self.id_type = _rtype(uint64, self._data['swap_endian'])
else:
raise Exception('Number of bytes in id block (%d) should be 4 or 8x\nnumber of particles (%d)!'%(id_block_len, self.num_particles_file))
f.close()
def __init__(self, filename):
""" Read the binary GADGET header of a format 2 snapshot """
file = open(filename, mode='rb')
file.seek(16) # skip 4 HEAD 264 4
header = binary_snapshot_io.read_header(file)
self._data = header
del self._data['buffer']
self.num_particles_file = np.sum(self._data['num_particles'])
if self._data['flag_doubleprecision']:
self.dtype = _rtype(float64, self._data['swap_endian'])
else:
self.dtype = _rtype(float32, self._data['swap_endian'])
self.dtype_width = np.dtype(self.dtype).itemsize
# Now build the list of labels
u32 = _rtype(uint32, self._data['swap_endian'])
file_offset = 8
self._file_offsets = {'HEAD':file_offset}
file_offset += 24 + 256
while True:
eight = file.read(4)
if len(eight)==0:
break
n = np.fromstring(eight, u32,1)[0]
assert(n==8)
name = file.read(4)
file_offset += 8
#print 'Found name', name
self._file_offsets[name] = file_offset
count = np.fromfile(file, u32,1)[0]
file.read(4)
count2 = np.fromfile(file, u32,1)[0]
file.seek(count2+4, 1)
file_offset += count2+16
file.close()
# Also find length of id block (by differencing file offsets between this block and next)
ordered_blocks = sorted(self._file_offsets.keys(), key=self._file_offsets.__getitem__)
next_block = ordered_blocks[ordered_blocks.index('ID ')+1]
id_block_len = self._file_offsets[next_block] - self._file_offsets['ID '] - 24
# print 'id_block_len', id_block_len
if id_block_len==4*self.num_particles_file:
self.long_ids = False
self.id_width = 4
self.id_type = _rtype(uint32, self._data['swap_endian'])
elif id_block_len==8*self.num_particles_file:
self.long_ids = True
self.id_width = 8
self.id_type = _rtype(uint64, self._data['swap_endian'])
else:
raise Exception('Number of bytes in id block (%d) should be 4 or 8x\nnumber of particles (%d)!'%(id_block_len, self.num_particles_file))