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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):
"""
NAME:
plotRotcurve
PURPOSE:
plot the rotation curve for this potential (in the z=0 plane for
non-spherical potentials)
INPUT:
Pot - Potential or list of Potential instances
Rrange - Range in R to consider (needs to be in the units that you are plotting; can be Quantity)
grid= grid in R
phi= (None) azimuth to use for non-axisymmetric potentials
savefilename= save to or restore from this savefile (pickle)
+galpy.util.plot.plot args and kwargs
OUTPUT:
plot to output device
HISTORY:
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.*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.])
# 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.,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.):
"""
NAME:
calcRotcurve
PURPOSE:
calculate the rotation curve for this potential (in the z=0 plane for
non-spherical potentials)
INPUT:
Pot - Potential or list of Potential instances
Rs - (array of) radius(i)
phi= (None) azimuth to use for non-axisymmetric potentials
ts - instantaneous time (optional)
OUTPUT:
array of vc
HISTORY:
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.):
"""
NAME:
vcirc
PURPOSE:
calculate the circular velocity at R in potential Pot
INPUT:
Pot - Potential instance or list of such instances
R - Galactocentric radius (can be Quantity)
phi= (None) azimuth to use for non-axisymmetric potentials
t= time (optional; can be Quantity)
OUTPUT:
circular rotation velocity
HISTORY:
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.):
"""
NAME:
dvcircdR
PURPOSE:
calculate the derivative of the circular velocity wrt R at R in potential Pot
INPUT:
Pot - Potential instance or list of such instances
R - Galactocentric radius (can be Quantity)
phi= (None) azimuth to use for non-axisymmetric potentials
t= time (optional; can be Quantity)
OUTPUT:
derivative of the circular rotation velocity wrt R
HISTORY:
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