def read_snap_galaxy_pcs(filename):
pcs_ds = ufmt(filename, 'r')
header = pcs_ds.read_record(dtype = header_dtype)[0]
# read header info / GALAXY 14.50 Manual, 9.2
n1, n2, n3 = header['n1'], header['n2'], header['n3']
N_pcs = n1 + n2 + n3
chunk_size = header['ncoor'] * header['np']
# assume 3D problem with equal-mass particles for each component
assert header['ncoor'] == 6
# read ptcls in batches
N_get = 0
pcs = np.empty(N_pcs * 6, dtype = 'f4')
while N_get < N_pcs * 6:
chunk_t = pcs_ds.read_reals(dtype = 'f4')
pcs[N_get: N_get + chunk_size] = chunk_t
N_get += chunk_t.size
pcs = pcs.reshape((-1, 6))
pcs_ds.close()
# Make them into components
snap = {'cps' : {},
'pm' : header['pm'],
'time': header['time']}
if n1 != 0: # component 1 has mtcls
snap['cps']['C1'] = {'N_pcs': n1,
'pm' : header['pm'],
'pcs' : pcs[:n1]}
if n2 != 0: # component 2 has ptcls
snap['cps']['C2'] = {'N_pcs': n2,
'pm' : header['pm'],
'pcs' : pcs[n1: n1 + n2]}
if n3 != 0: # component 3 has ptcls
snap['cps']['C3'] = {'N_pcs': n3,
'pm' : header['pm'],
'pcs' : pcs[n1 + n2: n1 + n2 + n3]}
return snap
def save_snap_galaxy_pcs(filename, snap):
# unpack snapshot
cps = snap['cps']
# Get ptcl number
n1, n2, n3 = 0, 0, 0
if(cps.has_key('C1')): n1 = cps['C1']['N_pcs']
if(cps.has_key('C2')): n2 = cps['C2']['N_pcs']
if(cps.has_key('C3')): n3 = cps['C3']['N_pcs']
N_pcs = n1 + n2 + n3
# Make array
pcs = np.empty(shape = (N_pcs, 6), dtype = 'f4')
if n1 != 0: pcs[:n1] = cps['C1']['pcs']
if n2 != 0: pcs[n1: n1 + n2] = cps['C2']['pcs']
if n3 != 0: pcs[n1 + n2: n1 + n2 + n3] = cps['C1']['pcs']
# prepare header,
header = np.empty(1, dtype = header_dtype)
header[0]['n1'] = n1
header[0]['n2'] = n2
header[0]['n3'] = n3
header[0]['ncoor'] = 6
header[0]['np'] = 5000
header[0]['time'] = snap['time']
header[0]['pm'] = snap['pm']
header[0]['pertbn'] = 0
# open a file, write the header
pcs_fs = ufmt(filename, 'w')
pcs_fs.write_record(header)
# write pcs array in batches of 5k ptcls
N_put, chunk_size = 0, 5000 * 6
pcs = pcs.reshape((-1,)) # into 1d array
while N_put < N_pcs * 6:
chunk_t = pcs[N_put: N_put + chunk_size]
pcs_fs.write_record(chunk_t)
N_put += chunk_t.size
pcs_fs.close()
return 0
