def test_fake_DMfit():
""" fit only for DM with fake TOAs
compare the variance of that result against the uncertainties
"""
parfile = pint.config.examplefile("NGC6440E.par")
timfile = pint.config.examplefile("NGC6440E.tim")
m, t = get_model_and_toas(parfile, timfile)
# pick only data for a DM fit
t = t[-8:]
m.RAJ.frozen = True
m.DECJ.frozen = True
m.F0.frozen = True
m.F1.frozen = True
f = GLSFitter(t, m)
f.fit_toas()
N = 30
DMs = np.zeros(N) * u.pc / u.cm**3
for iter in range(N):
t_fake = pint.simulation.make_fake_toas(t, m, add_noise=True)
f_fake = GLSFitter(t_fake, m)
f_fake.fit_toas()
DMs[iter] = f_fake.model.DM.quantity.astype(np.float64)
assert np.isclose(DMs.std(), f.model.DM.uncertainty, rtol=0.5)
assert np.abs(DMs.mean() -
f.model.DM.quantity) < 5 * f.model.DM.uncertainty
def calc_chi2(self, full_cov=False):
"""Return the weighted chi-squared for the model and toas.
If the errors on the TOAs are independent this is a straightforward
calculation, but if the noise model introduces correlated errors then
obtaining a meaningful chi-squared value requires a Cholesky
decomposition. This is carried out, here, by constructing a GLSFitter
and asking it to do the chi-squared computation but not a fit.
The return value here is available as self.chi2, which will not
redo the computation unless necessary.
The chi-squared value calculated here is suitable for use in downhill
minimization algorithms and Bayesian approaches.
Handling of problematic results - degenerate conditions explored by
a minimizer for example - may need to be checked to confirm that they
correctly return infinity.
"""
if self.model.has_correlated_errors:
# Use GLS but don't actually fit
from pint.fitter import GLSFitter
f = GLSFitter(self.toas, self.model, residuals=self)
try:
return f.fit_toas(maxiter=0, full_cov=full_cov)
except LinAlgError as e:
log.warning(
"Degenerate conditions encountered when "
"computing chi-squared: %s" % (e,)
)
return np.inf
else:
# Residual units are in seconds. Error units are in microseconds.
if (self.toas.get_errors() == 0.0).any():
return np.inf
else:
# The self.time_resids is in the unit of "s", the error "us".
# This is more correct way, but it is the slowest.
# return (((self.time_resids / self.toas.get_errors()).decompose()**2.0).sum()).value
# This method is faster then the method above but not the most correct way
# return ((self.time_resids.to(u.s) / self.toas.get_errors().to(u.s)).value**2.0).sum()
# This the fastest way, but highly depend on the assumption of time_resids and
# error units.
return (
(self.time_resids / self.toas.get_errors().to(u.s)) ** 2.0
).sum()
def test_residuals_gls_chi2():
model = get_model(
StringIO("""
PSRJ J1234+5678
ELAT 0
ELONG 0
DM 10
F0 1
PEPOCH 58000
ECORR mjd 57000 58000 2
"""))
toas = make_fake_toas(57000, 59000, 20, model=model, error=1 * u.us)
np.random.seed(0)
toas.adjust_TOAs(TimeDelta(np.random.randn(len(toas)) * u.us))
r = Residuals(toas, model)
f = GLSFitter(toas, model)
assert f.fit_toas() == r.chi2
def test_fake_from_timfile():
m, t = get_model_and_toas(
pint.config.examplefile("B1855+09_NANOGrav_9yv1.gls.par"),
pint.config.examplefile("B1855+09_NANOGrav_9yv1.tim"),
)
# refit the data to get rid of a trend
f = GLSFitter(t, m)
f.fit_toas()
r = pint.residuals.Residuals(t, f.model)
t_sim = pint.simulation.make_fake_toas(t, f.model, add_noise=True)
r_sim = pint.residuals.Residuals(t_sim, f.model)
# need a generous rtol because of the small statistics
assert np.isclose(r.calc_time_resids().std(),
r_sim.calc_time_resids().std(),
rtol=2)
def setUpClass(self):
self.par = 'B1855+09_NANOGrav_9yv1.gls.par'
self.tim = 'B1855+09_NANOGrav_9yv1.tim'
self.m = mb.get_model(self.par)
self.t = toa.get_TOAs(self.tim, ephem='DE436')
self.f = GLSFitter(self.t, self.m)
# get tempo2 parameter dict
with open('B1855+09_tempo2_gls_pars.json', 'r') as fp:
self.t2d = json.load(fp)
def test_gls_chi2_reasonable(full_cov):
model = get_model(
StringIO("""
PSRJ J1234+5678
ELAT 0
ELONG 0
DM 10
F0 1
PEPOCH 58000
TNRedAmp -14.227505410948254
TNRedGam 4.91353
TNRedC 45
"""))
toas = make_fake_toas(57000, 59000, 40, model=model, error=1 * u.us)
np.random.seed(0)
toas.adjust_TOAs(TimeDelta(np.random.randn(len(toas)) * u.us))
f = GLSFitter(toas, model)
fit_chi2 = f.fit_toas(full_cov=full_cov)
assert_allclose(fit_chi2, f.resids.calc_chi2(full_cov=full_cov))
def setUpClass(cls):
os.chdir(datadir)
cls.par = "B1855+09_NANOGrav_9yv1.gls.par"
cls.tim = "B1855+09_NANOGrav_9yv1.tim"
cls.m = mb.get_model(cls.par)
cls.t = toa.get_TOAs(cls.tim, ephem="DE436")
cls.f = GLSFitter(cls.t, cls.m)
# get tempo2 parameter dict
with open("B1855+09_tempo2_gls_pars.json", "r") as fp:
cls.t2d = json.load(fp)
def test_gls_covmatrix(wls):
gls = GLSFitter(wls.toas, wls.model_init)
gls.fit_toas()
assert np.isclose(
wls.parameter_covariance_matrix.matrix, gls.parameter_covariance_matrix.matrix
).all()
uncertainties = gls.model.get_params_dict("free", "uncertainty")
for param in uncertainties:
# uncertainty based on the diagonals of the covariance matrix
matrix_uncertainty = np.sqrt(
gls.parameter_covariance_matrix.get_label_matrix([param]).matrix[0, 0]
)
if param in ["RAJ", "DECJ"]:
# then uncertainties are in arcsec, need to convert
factor = 3600
else:
factor = 1
assert np.isclose(uncertainties[param] / factor, matrix_uncertainty)
def setUpClass(cls):
os.chdir(datadir)
cls.par = "B1855+09_NANOGrav_9yv1.gls.par"
cls.tim = "B1855+09_NANOGrav_9yv1.tim"
cls.m = mb.get_model(cls.par)
cls.t = toa.get_TOAs(cls.tim, ephem="DE436")
cls.f = GLSFitter(cls.t, cls.m)
# get tempo2 parameter dict
with open("B1855+09_tempo2_gls_pars.json", "r") as fp:
cls.t2d = json.load(fp)
# Get tempo whitened resids
mjd, cls.twres = (np.genfromtxt(
"B1855+09_NANOGrav_9yv1_whitened.tempo_test", unpack=True) * u.us)
def test_gls_chi2_behaviour():
model = get_model(
StringIO("""
PSRJ J1234+5678
ELAT 0
ELONG 0
DM 10
F0 1
PEPOCH 58000
TNRedAmp -14.227505410948254
TNRedGam 4.91353
TNRedC 45
"""))
model.free_params = ["F0", "ELAT", "ELONG"]
toas = make_fake_toas(57000, 59000, 40, model=model, error=1 * u.us)
np.random.seed(0)
toas.adjust_TOAs(TimeDelta(np.random.randn(len(toas)) * u.us))
f = GLSFitter(toas, model)
initial_chi2 = Residuals(toas, model).calc_chi2()
fit_chi2 = f.fit_toas()
assert fit_chi2 <= initial_chi2
assert f.resids.calc_chi2() <= initial_chi2
assert initial_chi2 == Residuals(toas, model).calc_chi2()
def setUpClass(cls):
os.chdir(datadir)
cls.par = "J0023+0923_NANOGrav_11yv0.gls.par"
cls.tim = "J0023+0923_NANOGrav_11yv0.tim"
cls.m = mb.get_model(cls.par)
cls.t = toa.get_TOAs(cls.tim, ephem="DE436")
cls.f = GLSFitter(cls.t, cls.m)
# Get comparison resids and uncertainties
mjd, freq, res, err, ophase, chi2, info = np.genfromtxt(cls.par +
".resavg",
unpack=True)
cls.resavg_mjd = mjd * u.d
cls.resavg_freq = freq * u.MHz
cls.resavg_res = res * u.us
cls.resavg_err = err * u.us
cls.resavg_chi2 = chi2
class TestGLS(unittest.TestCase):
"""Compare delays from the dd model with tempo and PINT"""
@classmethod
def setUpClass(self):
self.par = 'B1855+09_NANOGrav_9yv1.gls.par'
self.tim = 'B1855+09_NANOGrav_9yv1.tim'
self.m = mb.get_model(self.par)
self.t = toa.get_TOAs(self.tim, ephem='DE436')
self.f = GLSFitter(self.t, self.m)
# get tempo2 parameter dict
with open('B1855+09_tempo2_gls_pars.json', 'r') as fp:
self.t2d = json.load(fp)
def fit(self, full_cov):
self.f.reset_model()
self.f.update_resids()
self.f.fit_toas(full_cov=full_cov)
def test_gls_fitter(self):
for full_cov in [True, False]:
self.fit(full_cov)
for par, val in sorted(self.t2d.items()):
if par not in ['F0']:
v = (getattr(self.f.model, par).value if par not in [
'ELONG', 'ELAT'
] else getattr(self.f.model, par).quantity.to(u.rad).value)
e = (getattr(self.f.model, par).uncertainty.value
if par not in ['ELONG', 'ELAT'] else getattr(
self.f.model, par).uncertainty.to(u.rad).value)
msg = 'Parameter {} does not match T2 for full_cov={}'.format(
par, full_cov)
assert np.abs(v - val[0]) <= val[1], msg
assert np.abs(v - val[0]) <= e, msg
assert np.abs(1 - val[1] / e) < 0.1, msg
def test_gls_compare(self):
self.fit(full_cov=False)
chi21 = self.f.resids.chi2
self.fit(full_cov=True)
chi22 = self.f.resids.chi2
assert np.allclose(chi21, chi22)
class TestGLS(unittest.TestCase):
"""Compare delays from the dd model with tempo and PINT"""
@classmethod
def setUpClass(self):
self.par = 'B1855+09_NANOGrav_9yv1.gls.par'
self.tim = 'B1855+09_NANOGrav_9yv1.tim'
self.m = mb.get_model(self.par)
self.t = toa.get_TOAs(self.tim, ephem='DE436')
self.f = GLSFitter(self.t, self.m)
# get tempo2 parameter dict
with open('B1855+09_tempo2_gls_pars.json', 'r') as fp:
self.t2d = json.load(fp)
def fit(self, full_cov):
self.f.reset_model()
self.f.update_resids()
self.f.fit_toas(full_cov=full_cov)
def test_gls_fitter(self):
for full_cov in [True, False]:
self.fit(full_cov)
for par, val in sorted(self.t2d.items()):
if par not in ['F0']:
v = (getattr(self.f.model, par).value if par not in
['ELONG', 'ELAT'] else
getattr(self.f.model, par).quantity.to(u.rad).value)
e = (getattr(self.f.model, par).uncertainty.value if par not
in ['ELONG', 'ELAT'] else
getattr(self.f.model, par).uncertainty.to(u.rad).value)
msg = 'Parameter {} does not match T2 for full_cov={}'.format(par, full_cov)
assert np.abs(v-val[0]) <= val[1], msg
assert np.abs(v-val[0]) <= e, msg
assert np.abs(1 - val[1]/e) < 0.1, msg
def test_gls_compare(self):
self.fit(full_cov=False)
chi21 = self.f.resids.chi2
self.fit(full_cov=True)
chi22 = self.f.resids.chi2
assert np.allclose(chi21, chi22)
def test_compare_gls(full_cov, wls):
gls = GLSFitter(wls.toas, wls.model_init)
gls.fit_toas(full_cov=full_cov)
assert abs(wls.resids.chi2 - gls.resids.chi2) < 0.01
