def setup_units(m, x):
"""
Sets up units for a ChaNGa simulation, defined by position and mass units.
* time unit = :math:`\\sqrt{L_{unit}^3/G M_{unit}}`
* velocity unit = :math:`L_{unit}/T_{unit}`
* temperature units = Kelvin
Parameters
----------
m, x : Unit, string, or SimArray
Define the mass and position units
Returns
-------
units : dict
A dictionary containing the units
"""
m_unit = get_units(m)
pos_unit = get_units(x)
# time units are sqrt(L^3/GM)
t_unit = np.sqrt((pos_unit**3)*np.power((G*m_unit), -1)).units
# velocity units are L/t
v_unit = (pos_unit/t_unit).ratio('km s**-1')
# Make it a unit
v_unit = pynbody.units.Unit('{0} km s**-1'.format(v_unit))
# Temperature (just a hard-coded default)
temp_unit = get_units('K')
units = {'m': m_unit, 't': t_unit, 'v': v_unit, 'x': pos_unit,
'temp': temp_unit}
return units
def setup_units(m, x):
"""
Sets up units for a ChaNGa simulation, defined by position and mass units.
* time unit = :math:`\\sqrt{L_{unit}^3/G M_{unit}}`
* velocity unit = :math:`L_{unit}/T_{unit}`
* temperature units = Kelvin
Parameters
----------
m, x : Unit, string, or SimArray
Define the mass and position units
Returns
-------
units : dict
A dictionary containing the units
"""
m_unit = get_units(m)
pos_unit = get_units(x)
# time units are sqrt(L^3/GM)
t_unit = np.sqrt((pos_unit**3) * np.power((G * m_unit), -1)).units
# velocity units are L/t
v_unit = (pos_unit / t_unit).ratio('km s**-1')
# Make it a unit
v_unit = pynbody.units.Unit('{0} km s**-1'.format(v_unit))
# Temperature (just a hard-coded default)
temp_unit = get_units('K')
units = {
'm': m_unit,
't': t_unit,
'v': v_unit,
'x': pos_unit,
'temp': temp_unit
}
return units
def waterfall(power, t=None, m=None, log=True, normalize=True,
cmap='cubehelix', vmin=None, vmax=None, colorbar=True):
"""
Generates a waterfall plot for power spectrum vs time for a simulation
Parameters
----------
power : array, SimArray
2D shape (nt, nm) array of power spectrum
t : array, SimArray
(optional) time points. 1D array
m : array, SimArray
(optional) Fourier mode numbers. 1D array
log: bool
logscale the colors
normalize : bool
Normalize by the DC component at each time step
cmap : str or colormap
colormap to use
vmin, vmax : float
limits
colorbar : bool
Display colorbar
Examples
--------
>>> flist = diskpy.pychanga.get_fnames('snapshot')
>>> m, power = diskpy.disk.powerspectrum_t(flist, spacing='log')
>>> waterfall(power)
"""
# Initialize m and t
nt, nm = power.shape
if m is None:
m = np.arange(nm)
if t is None:
t = np.arange(nt)
mMesh, tMesh = np.meshgrid(m, t)
# Normalize
if normalize:
# Power in DC component
p0 = power[:, 0, None]
# Make a 2D array (same shape as power)
p0 = np.dot(p0, np.ones([1, nm]))
# normalize
power = power/p0
# Set up log-scale for plot
if log:
norm = LogNorm(vmin, vmax)
else:
norm = None
plt.pcolormesh(tMesh[:, 1:], mMesh[:, 1:], power[:, 1:], norm=norm, \
cmap = cmap)
plt.ylim(m[1], m[-1])
plt.ylabel('m')
tUnits = get_units(t)
if tUnits == 1:
plt.xlabel('time step')
else:
plt.xlabel(' time $(' + tUnits.latex() + ')$')
if colorbar:
cbar = plt.colorbar()
if normalize:
text = r'$A_m/A_0$'
else:
units = get_units(power)
text = r'$A_m (' + units.latex() + r') $'
cbar.set_label(text)
def waterfall(power, t=None, m=None, log=True, normalize=True,
cmap='cubehelix', vmin=None, vmax=None, colorbar=True):
"""
Generates a waterfall plot for power spectrum vs time for a simulation
Parameters
----------
power : array, SimArray
2D shape (nt, nm) array of power spectrum
t : array, SimArray
(optional) time points. 1D array
m : array, SimArray
(optional) Fourier mode numbers. 1D array
log: bool
logscale the colors
normalize : bool
Normalize by the DC component at each time step
cmap : str or colormap
colormap to use
vmin, vmax : float
limits
colorbar : bool
Display colorbar
Examples
--------
>>> flist = diskpy.pychanga.get_fnames('snapshot')
>>> m, power = diskpy.disk.powerspectrum_t(flist, spacing='log')
>>> waterfall(power)
"""
# Initialize m and t
nt, nm = power.shape
if m is None:
m = np.arange(nm)
if t is None:
t = np.arange(nt)
mMesh, tMesh = np.meshgrid(m, t)
# Normalize
if normalize:
# Power in DC component
p0 = power[:, 0, None]
# Make a 2D array (same shape as power)
p0 = np.dot(p0, np.ones([1, nm]))
# normalize
power = power/p0
# Set up log-scale for plot
if log:
norm = LogNorm(vmin, vmax)
else:
norm = None
plt.pcolormesh(tMesh[:, 1:], mMesh[:, 1:], power[:, 1:], norm=norm, \
cmap = cmap)
plt.ylim(m[1], m[-1])
plt.ylabel('m')
tUnits = get_units(t)
if tUnits == 1:
plt.xlabel('time step')
else:
plt.xlabel(' time $(' + tUnits.latex() + ')$')
if colorbar:
cbar = plt.colorbar()
if normalize:
text = r'$A_m/A_0$'
else:
units = get_units(power)
text = r'$A_m (' + units.latex() + r') $'
cbar.set_label(text)