def get_lightcone_subvolume(lightcone, redshifts, central_z, \
depth_mhz=None, depth_mpc=None, odd_num_cells=True, \
subtract_mean=True, fov_Mpc=None):
'''
Extract a subvolume from a lightcone, at a given central redshift,
and with a given depth. The depth can be specified in Mpc or MHz.
You must give exactly one of these parameters.
Parameters:
* ligthcone (numpy array): the lightcone
* redshifts (numpy array): the redshifts along the LOS
* central_z (float): the central redshift of the subvolume
* depth_mhz (float): the depth of the subvolume in MHz
* depth_mpc (float): the depth of the subvolume in Mpc
* odd_num_cells (bool): if true, the depth of the box will always
be an odd number of cells. This avoids problems with
power spectrum calculations.
* subtract_mean (bool): if true, subtract the mean of the signal (Default: True)
* fov_Mpc (float): the FoV size in Mpc
Returns:
Tuple with (subvolume, dims) where dims is a tuple
with the dimensions of the subvolume in Mpc
'''
assert len(np.nonzero([depth_mhz, depth_mpc])) == 1
if fov_Mpc == None:
fov_Mpc = conv.LB
central_nu = cm.z_to_nu(central_z)
if depth_mpc != None: #Depth is given in Mpc
central_dist = cm.nu_to_cdist(central_nu)
low_z = cm.cdist_to_z(central_dist-depth_mpc/2.)
high_z = cm.cdist_to_z(central_dist+depth_mpc/2.)
else: #Depth is given in MHz
low_z = cm.nu_to_z(central_nu+depth_mhz/2.)
high_z = cm.nu_to_z(central_nu-depth_mhz/2.)
if low_z < redshifts.min():
raise Exception('Lowest z is outside range')
if high_z > redshifts.max():
raise Exception('Highest z is outside range')
low_n = int(find_idx(redshifts, low_z))
high_n = int(find_idx(redshifts, high_z))
if (high_n-low_n) % 2 == 0 and odd_num_cells:
high_n += 1
subbox = lightcone[:,:,low_n:high_n]
if subtract_mean:
subbox = st.subtract_mean_signal(subbox, los_axis=2)
box_depth = float(subbox.shape[2])/lightcone.shape[1]*fov_Mpc
box_dims = (fov_Mpc, fov_Mpc, box_depth)
return subbox, box_dims
def get_lightcone_subvolume(lightcone, redshifts, central_z, \
depth_mhz=None, depth_mpc=None, odd_num_cells=True, \
subtract_mean=True, fov_Mpc=None):
'''
Extract a subvolume from a lightcone, at a given central redshift,
and with a given depth. The depth can be specified in Mpc or MHz.
You must give exactly one of these parameters.
Parameters:
* ligthcone (numpy array): the lightcone
* redshifts (numpy array): the redshifts along the LOS
* central_z (float): the central redshift of the subvolume
* depth_mhz (float): the depth of the subvolume in MHz
* depth_mpc (float): the depth of the subvolume in Mpc
* odd_num_cells (bool): if true, the depth of the box will always
be an odd number of cells. This avoids problems with
power spectrum calculations.
* subtract_mean (bool): if true, subtract the mean of the signal (Default: True)
* fov_Mpc (float): the FoV size in Mpc
Returns:
Tuple with (subvolume, dims) where dims is a tuple
with the dimensions of the subvolume in Mpc
'''
assert len(np.nonzero([depth_mhz, depth_mpc])) == 1
if fov_Mpc == None:
fov_Mpc = conv.LB
central_nu = cm.z_to_nu(central_z)
if depth_mpc != None: #Depth is given in Mpc
central_dist = cm.nu_to_cdist(central_nu)
low_z = cm.cdist_to_z(central_dist - depth_mpc / 2.)
high_z = cm.cdist_to_z(central_dist + depth_mpc / 2.)
else: #Depth is given in MHz
low_z = cm.nu_to_z(central_nu + depth_mhz / 2.)
high_z = cm.nu_to_z(central_nu - depth_mhz / 2.)
if low_z < redshifts.min():
raise Exception('Lowest z is outside range')
if high_z > redshifts.max():
raise Exception('Highest z is outside range')
low_n = int(find_idx(redshifts, low_z))
high_n = int(find_idx(redshifts, high_z))
if (high_n - low_n) % 2 == 0 and odd_num_cells:
high_n += 1
subbox = lightcone[:, :, low_n:high_n]
if subtract_mean:
subbox = st.subtract_mean_signal(subbox, los_axis=2)
box_depth = float(subbox.shape[2]) / lightcone.shape[1] * fov_Mpc
box_dims = (fov_Mpc, fov_Mpc, box_depth)
return subbox, box_dims
def bin_lightcone_in_frequency(lightcone, z_low, box_size_mpc, dnu):
'''
Bin a lightcone in frequency bins.
Parameters:
* lightcone (numpy array): the lightcone in length units
* z_low (float): the lowest redshift of the lightcone
* box_size_mpc (float): the side of the lightcone in Mpc
* dnu (float): the width of the frequency bins in MHz
Returns:
The lightcone, binned in frequencies with high frequencies first
The frequencies along the line of sight in MHz
'''
#Figure out dimensions and make output volume
cell_size = box_size_mpc / lightcone.shape[0]
distances = cm.z_to_cdist(z_low) + np.arange(
lightcone.shape[2]) * cell_size
input_redshifts = cm.cdist_to_z(distances)
input_frequencies = cm.z_to_nu(input_redshifts)
nu1 = input_frequencies[0]
nu2 = input_frequencies[-1]
output_frequencies = np.arange(nu1, nu2, -dnu)
output_lightcone = np.zeros((lightcone.shape[0], lightcone.shape[1], \
len(output_frequencies)))
#Bin in frequencies by smoothing and indexing
max_cell_size = cm.nu_to_cdist(output_frequencies[-1]) - cm.nu_to_cdist(
output_frequencies[-2])
smooth_scale = np.round(max_cell_size / cell_size)
if smooth_scale < 1:
smooth_scale = 1
hf.print_msg('Smooth along LoS with scale %f' % smooth_scale)
tophat3d = np.ones((1, 1, smooth_scale))
tophat3d /= np.sum(tophat3d)
lightcone_smoothed = scipy.signal.fftconvolve(lightcone,
tophat3d,
mode='same')
for i in range(output_lightcone.shape[2]):
nu = output_frequencies[i]
idx = hf.find_idx(input_frequencies, nu)
output_lightcone[:, :, i] = lightcone_smoothed[:, :, idx]
return output_lightcone, output_frequencies
def bin_lightcone_in_frequency(lightcone, z_low, box_size_mpc, dnu):
'''
Bin a lightcone in frequency bins.
Parameters:
* lightcone (numpy array): the lightcone in length units
* z_low (float): the lowest redshift of the lightcone
* box_size_mpc (float): the side of the lightcone in Mpc
* dnu (float): the width of the frequency bins in MHz
Returns:
The lightcone, binned in frequencies with high frequencies first
The frequencies along the line of sight in MHz
'''
#Figure out dimensions and make output volume
cell_size = box_size_mpc/lightcone.shape[0]
distances = cm.z_to_cdist(z_low) + np.arange(lightcone.shape[2])*cell_size
input_redshifts = cm.cdist_to_z(distances)
input_frequencies = cm.z_to_nu(input_redshifts)
nu1 = input_frequencies[0]
nu2 = input_frequencies[-1]
output_frequencies = np.arange(nu1, nu2, -dnu)
output_lightcone = np.zeros((lightcone.shape[0], lightcone.shape[1], \
len(output_frequencies)))
#Bin in frequencies by smoothing and indexing
max_cell_size = cm.nu_to_cdist(output_frequencies[-1])-cm.nu_to_cdist(output_frequencies[-2])
smooth_scale = np.round(max_cell_size/cell_size)
if smooth_scale < 1:
smooth_scale = 1
hf.print_msg('Smooth along LoS with scale %f' % smooth_scale)
tophat3d = np.ones((1,1,smooth_scale))
tophat3d /= np.sum(tophat3d)
lightcone_smoothed = fftconvolve(lightcone, tophat3d)
for i in range(output_lightcone.shape[2]):
nu = output_frequencies[i]
idx = hf.find_idx(input_frequencies, nu)
output_lightcone[:,:,i] = lightcone_smoothed[:,:,idx]
return output_lightcone, output_frequencies
