/
plotRotcurve.py
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plotRotcurve.py
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import os
import pickle
import numpy
from ..util import conversion, plot
from ..util.conversion import (
parse_length,
parse_velocity,
physical_conversion,
potential_physical_input,
)
def plotRotcurve(Pot, *args, **kwargs):
"""
Plot the rotation curve for this potential (in the z=0 plane for non-spherical potentials).
Parameters
----------
Pot : Potential or list of Potential instances
Potential instance or list of such instances.
Rrange : numpy.ndarray or Quantity
Range in R to consider (needs to be in the units that you are plotting).
grid : int, optional
Number of grid points in R.
phi : float or Quantity, optional
Azimuth to use for non-axisymmetric potentials.
savefilename : str, optional
Save to or restore from this savefile (pickle).
*args
Arguments passed to `galpy.util.plot.plot`.
**kwargs
Keyword arguments passed to `galpy.util.plot.plot`.
Returns
-------
matplotlib.Axes
Axes on which the plot was drawn.
Notes
-----
- 2010-07-10 - Written - Bovy (NYU)
- 2016-06-15 - Added phi= keyword for non-axisymmetric potential - Bovy (UofT)
"""
# Using physical units or not?
if isinstance(Pot, list):
potro = Pot[0]._ro
roSet = Pot[0]._roSet
potvo = Pot[0]._vo
voSet = Pot[0]._voSet
else:
potro = Pot._ro
roSet = Pot._roSet
potvo = Pot._vo
voSet = Pot._voSet
# Following just to deal with Quantity ro/vo and check whether they are set
_ro = parse_length(kwargs.get("ro", None), ro=potro)
_vo = parse_velocity(kwargs.get("vo", None), vo=potvo)
if (
kwargs.get("use_physical", True)
and (not _ro is None or roSet)
and (not _vo is None or voSet)
):
use_physical = True
potro = kwargs.get("ro", potro)
potvo = kwargs.get("vo", potvo)
xlabel = r"$R\,(\mathrm{kpc})$"
ylabel = r"$v_c(R)\,(\mathrm{km\,s}^{-1})$"
Rrange = kwargs.pop("Rrange", [0.01 * potro, 5.0 * potro])
else:
use_physical = False
xlabel = r"$R/R_0$"
ylabel = r"$v_c(R)/v_c(R_0)$"
Rrange = kwargs.pop("Rrange", [0.01, 5.0])
# Parse ro
potro = conversion.parse_length_kpc(potro)
potvo = conversion.parse_velocity_kms(potvo)
Rrange[0] = conversion.parse_length_kpc(Rrange[0])
Rrange[1] = conversion.parse_length_kpc(Rrange[1])
if use_physical:
Rrange[0] /= potro
Rrange[1] /= potro
grid = kwargs.pop("grid", 1001)
savefilename = kwargs.pop("savefilename", None)
phi = kwargs.pop("phi", None)
if not savefilename is None and os.path.exists(savefilename):
print("Restoring savefile " + savefilename + " ...")
savefile = open(savefilename, "rb")
rotcurve = pickle.load(savefile)
Rs = pickle.load(savefile)
savefile.close()
else:
Rs = numpy.linspace(Rrange[0], Rrange[1], grid)
rotcurve = calcRotcurve(Pot, Rs, phi=phi)
if not savefilename == None:
print("Writing savefile " + savefilename + " ...")
savefile = open(savefilename, "wb")
pickle.dump(rotcurve, savefile)
pickle.dump(Rs, savefile)
savefile.close()
if use_physical:
Rs *= potro
rotcurve *= potvo
Rrange[0] *= potro
Rrange[1] *= potro
if not "xlabel" in kwargs:
kwargs["xlabel"] = xlabel
if not "ylabel" in kwargs:
kwargs["ylabel"] = ylabel
if not "xrange" in kwargs:
kwargs["xrange"] = Rrange
if not "yrange" in kwargs:
kwargs["yrange"] = [0.0, 1.2 * numpy.amax(rotcurve)]
kwargs.pop("ro", None)
kwargs.pop("vo", None)
kwargs.pop("use_physical", None)
return plot.plot(Rs, rotcurve, *args, **kwargs)
def calcRotcurve(Pot, Rs, phi=None, t=0.0):
"""
Calculate the rotation curve for this potential (in the z=0 plane for non-spherical potentials).
Parameters
----------
Pot : Potential or list of Potential instances
Potential instance or list of such instances.
Rs : numpy.ndarray or float
Radius(i).
phi : float or Quantity, optional
Azimuth to use for non-axisymmetric potentials.
t : float or Quantity, optional
Instantaneous time (default: 0.0)
Returns
-------
numpy.ndarray
Array of circular rotation velocities.
Notes
-----
- 2011-04-13 - Written - Bovy (NYU)
- 2016-06-15 - Added phi= keyword for non-axisymmetric potential - Bovy (UofT)
"""
try:
grid = len(Rs)
except TypeError:
grid = 1
Rs = numpy.array([Rs])
rotcurve = numpy.zeros(grid)
for ii in range(grid):
rotcurve[ii] = vcirc(Pot, Rs[ii], phi=phi, t=t, use_physical=False)
return rotcurve
@potential_physical_input
@physical_conversion("velocity", pop=True)
def vcirc(Pot, R, phi=None, t=0.0):
"""
Calculate the circular velocity at R in potential Pot.
Parameters
----------
Pot : Potential or list of Potential instances
Potential instance or list of such instances.
R : float or Quantity
Galactocentric radius.
phi : float or Quantity, optional
Azimuth to use for non-axisymmetric potentials.
t : float or Quantity, optional
Instantaneous time (default: 0.0)
Returns
-------
float or Quantity
Circular rotation velocity.
Notes
-----
- 2011-10-09 - Written - Bovy (IAS)
- 2016-06-15 - Added phi= keyword for non-axisymmetric potential - Bovy (UofT)
"""
from ..potential import PotentialError, evaluateplanarRforces
try:
return numpy.sqrt(
-R * evaluateplanarRforces(Pot, R, phi=phi, t=t, use_physical=False)
)
except PotentialError:
from ..potential import toPlanarPotential
Pot = toPlanarPotential(Pot)
return numpy.sqrt(
-R * evaluateplanarRforces(Pot, R, phi=phi, t=t, use_physical=False)
)
@potential_physical_input
@physical_conversion("frequency", pop=True)
def dvcircdR(Pot, R, phi=None, t=0.0):
"""
Calculate the derivative of the circular velocity wrt R at R in potential Pot.
Parameters
----------
Pot : Potential or list of Potential instances
Potential instance or list of such instances.
R : float or Quantity
Galactocentric radius.
phi : float or Quantity, optional
Azimuth to use for non-axisymmetric potentials.
t : float, optional
Instantaneous time (default: 0)
Returns
-------
float or Quantity
Derivative of the circular rotation velocity wrt R.
Notes
-----
- 2013-01-08 - Written - Bovy (IAS)
- 2016-06-28 - Added phi= keyword for non-axisymmetric potential - Bovy (UofT)
"""
from ..potential import (
PotentialError,
evaluateplanarR2derivs,
evaluateplanarRforces,
)
tvc = vcirc(Pot, R, phi=phi, t=t, use_physical=False)
try:
return (
0.5
* (
-evaluateplanarRforces(Pot, R, phi=phi, t=t, use_physical=False)
+ R * evaluateplanarR2derivs(Pot, R, phi=phi, t=t, use_physical=False)
)
/ tvc
)
except PotentialError:
from ..potential import RZToplanarPotential
Pot = RZToplanarPotential(Pot)
return (
0.5
* (
-evaluateplanarRforces(Pot, R, phi=phi, t=t, use_physical=False)
+ R * evaluateplanarR2derivs(Pot, R, phi=phi, t=t, use_physical=False)
)
/ tvc
)