def calc_rungdist(param_name, dDelta):
"""
Calls ChaNGa to calculate the rung distribution
"""
changa_args = '+n 1 -dt {}'.format(dDelta)
command = ICgen_utils.changa_command(param_name, changa_args=changa_args, preset='isaac')
p = ICgen_utils.changa_run(command, verbose=False)
return read_rungdist(p)
def calc_rungdist(param_name, dDelta):
"""
Calls ChaNGa to calculate the rung distribution
"""
changa_args = '+n 1 -dt {}'.format(dDelta)
command = ICgen_utils.changa_command(param_name,
changa_args=changa_args,
preset='isaac')
p = ICgen_utils.changa_run(command, verbose=False)
return read_rungdist(p)
def v_xy(f, param, changbin=None, nr=50, min_per_bin=100, changa_preset=None, \
max_particles=None, est_eps=True):
"""
Attempts to calculate the circular velocities for particles in a thin
(not flat) keplerian disk. Also estimates gravitational softening (eps)
for the gas particles
Requires ChaNGa
Note that this will change the velocities IN f
**ARGUMENTS**
f : tipsy snapshot
For a gaseous disk
param : dict
a dictionary containing params for changa. (see isaac.configparser)
changbin : str (OPTIONAL)
If set, should be the full path to the ChaNGa executable. If None,
an attempt to find ChaNGa is made
nr : int (optional)
number of radial bins to use when averaging over accelerations
min_per_bin : int (optional)
The minimum number of particles to be in each bin. If there are too
few particles in a bin, it is merged with an adjacent bin. Thus,
actual number of radial bins may be less than nr.
changa_preset : str
Which ChaNGa execution preset to use (ie 'mpi', 'local', ...). See
ICgen_utils.changa_command
max_particles : int or None
Specifies the maximum number of particles to use for calculating
accelerations and velocities. Setting a smaller number can speed up
computation and save on memory but can yield noisier results.
If None, max is unlimited.
est_eps : bool
Estimate eps (gravitational softening length). Default is True.
If False, it is assumed eps has already been estimated
**RETURNS**
Nothing. Velocities are updated within f as is eps
"""
# If the snapshot has too many particles, randomly select gas particles
# To use for calculating velocity and make a view of the snapshot
n_gas = len(f) - 1
subview = (n_gas > max_particles) and (max_particles is not None)
if subview:
max_particles = int(max_particles)
mask = np.zeros(n_gas + 1, dtype=bool)
mask[-1] = True # Use the star particle always
# randomly select particles to use
m = np.random.rand(n_gas)
ind = m.argsort()[0:max_particles]
mask[ind] = True
# Make a subview and create a reference to the complete snapshot
complete_snapshot = f
f = complete_snapshot[mask]
# Scale gas mass
m_scale = float(n_gas)/float(max_particles)
f.g['mass'] *= m_scale
if not est_eps:
f.g['eps'] *= m_scale**(1.0/3)
# Load stuff from the snapshot
r = f.g['rxy'].astype(np.float32)
cosine = (f.g['x']/r).in_units('1').astype(np.float32)
sine = (f.g['y']/r).in_units('1').astype(np.float32)
z = f.g['z']
vel = f.g['vel']
a = None # arbitrary initialization
# Temporary filenames for running ChaNGa
f_prefix = str(np.random.randint(0, 2**32))
f_name = f_prefix + '.std'
p_name = f_prefix + '.param'
# Update parameters
p_temp = param.copy()
p_temp['achInFile'] = f_name
p_temp['achOutName'] = f_prefix
p_temp['dDelta'] = 1e-10
if 'dDumpFrameTime' in p_temp: p_temp.pop('dDumpFrameTime')
if 'dDumpFrameStep' in p_temp: p_temp.pop('dDumpFrameStep')
# --------------------------------------------
# Estimate velocity from gravity only
# --------------------------------------------
for iGrav in range(2):
# Save files
f.write(filename=f_name, fmt = pynbody.tipsy.TipsySnap)
isaac.configsave(p_temp, p_name, ftype='param')
if iGrav == 0:
# Run ChaNGa calculating all forces (for initial run)
command = ICgen_utils.changa_command(p_name, changa_preset, changbin, '+gas +n 0')
else:
# Run ChaNGa, only calculating gravity (on second run)
command = ICgen_utils.changa_command(p_name, changa_preset, changbin, '-gas +n 0')
print command
p = ICgen_utils.changa_run(command)
p.wait()
if (iGrav == 0) and est_eps:
# Estimate the gravitational softening length on the first iteration
smoothlength_file = f_prefix + '.000000.smoothlength'
eps = ICgen_utils.est_eps(smoothlength_file)
f.g['eps'] = eps
# Load accelerations
acc_name = f_prefix + '.000000.acc2'
del a
gc.collect()
a = isaac.load_acc(acc_name, low_mem=True)
gc.collect()
# Clean-up
for fname in glob.glob(f_prefix + '*'): os.remove(fname)
# Calculate cos(theta) where theta is angle above x-y plane
cos = (r/np.sqrt(r**2 + z**2)).in_units('1').astype(np.float32)
# Calculate radial acceleration times r^2
ar2 = (a[:,0]*cosine + a[:,1]*sine)*r**2
# Bin the data
r_edges = np.linspace(r.min(), (1+np.spacing(2))*r.max(), nr + 1)
ind, r_edges = isaac.digitize_threshold(r, min_per_bin, r_edges)
ind -= 1
nr = len(r_edges) - 1
r_bins, ar2_mean, err = isaac.binned_mean(r, ar2, binedges=r_edges, \
weighted_bins=True)
gc.collect()
# Fit lines to ar2 vs cos for each radial bin
m = np.zeros(nr)
b = np.zeros(nr)
for i in range(nr):
mask = (ind == i)
p = np.polyfit(cos[mask], ar2[mask], 1)
m[i] = p[0]
b[i] = p[1]
# Interpolate the line fits
m_spline = isaac.extrap1d(r_bins, m)
b_spline = isaac.extrap1d(r_bins, b)
# Calculate circular velocity
ar2 = SimArray(m_spline(r)*cos + b_spline(r), ar2.units)
gc.collect()
v_calc = (np.sqrt(abs(ar2)/r)).in_units(vel.units)
gc.collect()
vel[:,0] = -v_calc*sine
vel[:,1] = v_calc*cosine
del v_calc
gc.collect()
# --------------------------------------------
# Estimate pressure/gas dynamics accelerations
# --------------------------------------------
# Save files
f.write(filename=f_name, fmt = pynbody.tipsy.TipsySnap)
isaac.configsave(p_temp, p_name, ftype='param')
# Run ChaNGa, including SPH
command = ICgen_utils.changa_command(p_name, changa_preset, changbin, '+gas -n 0')
p = ICgen_utils.changa_run(command)
p.wait()
# Load accelerations
acc_name = f_prefix + '.000000.acc2'
a_total = isaac.load_acc(acc_name, low_mem=True)
gc.collect()
# Clean-up
for fname in glob.glob(f_prefix + '*'): os.remove(fname)
# Estimate the accelerations due to pressure gradients/gas dynamics
a_gas = a_total - a
del a_total, a
gc.collect()
ar2_gas = (a_gas[:,0]*cosine + a_gas[:,1]*sine)*r**2
del a_gas
gc.collect()
logr_bins, ratio, err = isaac.binned_mean(np.log(r), ar2_gas/ar2, nbins=nr,\
weighted_bins=True)
r_bins = np.exp(logr_bins)
del ar2_gas
gc.collect()
ratio_spline = isaac.extrap1d(r_bins, ratio)
# If not all the particles were used for calculating velocity,
# Make sure to use them now
if subview:
# Re-scale mass back to normal
f.g['mass'] /= m_scale
# Scale eps appropriately
f.g['eps'] /= m_scale**(1.0/3)
complete_snapshot.g['eps'] = f.g['eps'][[0]]
# Rename complete snapshot
f = complete_snapshot
# Calculate stuff for all particles
r = f.g['rxy']
z = f.g['z']
cos = (r/np.sqrt(r**2 + z**2)).in_units('1').astype(np.float32)
ar2 = SimArray(m_spline(r)*cos + b_spline(r), ar2.units)
cosine = (f.g['x']/r).in_units('1').astype(np.float32)
sine = (f.g['y']/r).in_units('1').astype(np.float32)
vel = f.g['vel']
ar2_calc = ar2*(1 + ratio_spline(r))
del ar2
gc.collect()
# Calculate velocity
v = (np.sqrt(abs(ar2_calc)/r)).in_units(f.g['vel'].units)
del ar2_calc
gc.collect()
vel[:,0] = -v*sine
vel[:,1] = v*cosine
return
def v_xy(f, param, changbin=None, nr=50, min_per_bin=100, changa_preset=None, \
max_particles=None, est_eps=True):
"""
Attempts to calculate the circular velocities for particles in a thin
(not flat) keplerian disk. Also estimates gravitational softening (eps)
for the gas particles
Requires ChaNGa
Note that this will change the velocities IN f
**ARGUMENTS**
f : tipsy snapshot
For a gaseous disk
param : dict
a dictionary containing params for changa. (see isaac.configparser)
changbin : str (OPTIONAL)
If set, should be the full path to the ChaNGa executable. If None,
an attempt to find ChaNGa is made
nr : int (optional)
number of radial bins to use when averaging over accelerations
min_per_bin : int (optional)
The minimum number of particles to be in each bin. If there are too
few particles in a bin, it is merged with an adjacent bin. Thus,
actual number of radial bins may be less than nr.
changa_preset : str
Which ChaNGa execution preset to use (ie 'mpi', 'local', ...). See
ICgen_utils.changa_command
max_particles : int or None
Specifies the maximum number of particles to use for calculating
accelerations and velocities. Setting a smaller number can speed up
computation and save on memory but can yield noisier results.
If None, max is unlimited.
est_eps : bool
Estimate eps (gravitational softening length). Default is True.
If False, it is assumed eps has already been estimated
**RETURNS**
Nothing. Velocities are updated within f as is eps
"""
# If the snapshot has too many particles, randomly select gas particles
# To use for calculating velocity and make a view of the snapshot
n_gas = len(f) - 1
subview = (n_gas > max_particles) and (max_particles is not None)
if subview:
max_particles = int(max_particles)
mask = np.zeros(n_gas + 1, dtype=bool)
mask[-1] = True # Use the star particle always
# randomly select particles to use
m = np.random.rand(n_gas)
ind = m.argsort()[0:max_particles]
mask[ind] = True
# Make a subview and create a reference to the complete snapshot
complete_snapshot = f
f = complete_snapshot[mask]
# Scale gas mass
m_scale = float(n_gas) / float(max_particles)
f.g['mass'] *= m_scale
if not est_eps:
f.g['eps'] *= m_scale**(1.0 / 3)
# Load stuff from the snapshot
r = f.g['rxy'].astype(np.float32)
cosine = (f.g['x'] / r).in_units('1').astype(np.float32)
sine = (f.g['y'] / r).in_units('1').astype(np.float32)
z = f.g['z']
vel = f.g['vel']
a = None # arbitrary initialization
# Temporary filenames for running ChaNGa
f_prefix = str(np.random.randint(0, 2**32))
f_name = f_prefix + '.std'
p_name = f_prefix + '.param'
# Update parameters
p_temp = param.copy()
p_temp['achInFile'] = f_name
p_temp['achOutName'] = f_prefix
p_temp['dDelta'] = 1e-10
if 'dDumpFrameTime' in p_temp: p_temp.pop('dDumpFrameTime')
if 'dDumpFrameStep' in p_temp: p_temp.pop('dDumpFrameStep')
# --------------------------------------------
# Estimate velocity from gravity only
# --------------------------------------------
for iGrav in range(2):
# Save files
f.write(filename=f_name, fmt=pynbody.tipsy.TipsySnap)
isaac.configsave(p_temp, p_name, ftype='param')
if iGrav == 0:
# Run ChaNGa calculating all forces (for initial run)
command = ICgen_utils.changa_command(p_name, changa_preset,
changbin, '+gas +n 0')
else:
# Run ChaNGa, only calculating gravity (on second run)
command = ICgen_utils.changa_command(p_name, changa_preset,
changbin, '-gas +n 0')
print command
p = ICgen_utils.changa_run(command)
p.wait()
if (iGrav == 0) and est_eps:
# Estimate the gravitational softening length on the first iteration
smoothlength_file = f_prefix + '.000000.smoothlength'
eps = ICgen_utils.est_eps(smoothlength_file)
f.g['eps'] = eps
# Load accelerations
acc_name = f_prefix + '.000000.acc2'
del a
gc.collect()
a = isaac.load_acc(acc_name, low_mem=True)
gc.collect()
# Clean-up
for fname in glob.glob(f_prefix + '*'):
os.remove(fname)
# Calculate cos(theta) where theta is angle above x-y plane
cos = (r / np.sqrt(r**2 + z**2)).in_units('1').astype(np.float32)
# Calculate radial acceleration times r^2
ar2 = (a[:, 0] * cosine + a[:, 1] * sine) * r**2
# Bin the data
r_edges = np.linspace(r.min(), (1 + np.spacing(2)) * r.max(), nr + 1)
ind, r_edges = isaac.digitize_threshold(r, min_per_bin, r_edges)
ind -= 1
nr = len(r_edges) - 1
r_bins, ar2_mean, err = isaac.binned_mean(r, ar2, binedges=r_edges, \
weighted_bins=True)
gc.collect()
# Fit lines to ar2 vs cos for each radial bin
m = np.zeros(nr)
b = np.zeros(nr)
for i in range(nr):
mask = (ind == i)
p = np.polyfit(cos[mask], ar2[mask], 1)
m[i] = p[0]
b[i] = p[1]
# Interpolate the line fits
m_spline = isaac.extrap1d(r_bins, m)
b_spline = isaac.extrap1d(r_bins, b)
# Calculate circular velocity
ar2 = SimArray(m_spline(r) * cos + b_spline(r), ar2.units)
gc.collect()
v_calc = (np.sqrt(abs(ar2) / r)).in_units(vel.units)
gc.collect()
vel[:, 0] = -v_calc * sine
vel[:, 1] = v_calc * cosine
del v_calc
gc.collect()
# --------------------------------------------
# Estimate pressure/gas dynamics accelerations
# --------------------------------------------
# Save files
f.write(filename=f_name, fmt=pynbody.tipsy.TipsySnap)
isaac.configsave(p_temp, p_name, ftype='param')
# Run ChaNGa, including SPH
command = ICgen_utils.changa_command(p_name, changa_preset, changbin,
'+gas -n 0')
p = ICgen_utils.changa_run(command)
p.wait()
# Load accelerations
acc_name = f_prefix + '.000000.acc2'
a_total = isaac.load_acc(acc_name, low_mem=True)
gc.collect()
# Clean-up
for fname in glob.glob(f_prefix + '*'):
os.remove(fname)
# Estimate the accelerations due to pressure gradients/gas dynamics
a_gas = a_total - a
del a_total, a
gc.collect()
ar2_gas = (a_gas[:, 0] * cosine + a_gas[:, 1] * sine) * r**2
del a_gas
gc.collect()
logr_bins, ratio, err = isaac.binned_mean(np.log(r), ar2_gas/ar2, nbins=nr,\
weighted_bins=True)
r_bins = np.exp(logr_bins)
del ar2_gas
gc.collect()
ratio_spline = isaac.extrap1d(r_bins, ratio)
# If not all the particles were used for calculating velocity,
# Make sure to use them now
if subview:
# Re-scale mass back to normal
f.g['mass'] /= m_scale
# Scale eps appropriately
f.g['eps'] /= m_scale**(1.0 / 3)
complete_snapshot.g['eps'] = f.g['eps'][[0]]
# Rename complete snapshot
f = complete_snapshot
# Calculate stuff for all particles
r = f.g['rxy']
z = f.g['z']
cos = (r / np.sqrt(r**2 + z**2)).in_units('1').astype(np.float32)
ar2 = SimArray(m_spline(r) * cos + b_spline(r), ar2.units)
cosine = (f.g['x'] / r).in_units('1').astype(np.float32)
sine = (f.g['y'] / r).in_units('1').astype(np.float32)
vel = f.g['vel']
ar2_calc = ar2 * (1 + ratio_spline(r))
del ar2
gc.collect()
# Calculate velocity
v = (np.sqrt(abs(ar2_calc) / r)).in_units(f.g['vel'].units)
del ar2_calc
gc.collect()
vel[:, 0] = -v * sine
vel[:, 1] = v * cosine
return
