def test_repeated_prediction_cache():
kernel = kernels.ExpSquaredKernel(1.0)
gp = GP(kernel)
x = np.array((-1, 0, 1))
gp.compute(x)
t = np.array((-.5, .3, 1.2))
y = x / x.std()
mu0, mu1 = (gp.predict(y, t, return_cov=False) for _ in range(2))
assert np.array_equal(mu0, mu1), \
"Identical training data must give identical predictions " \
"(problem with GP cache)."
y2 = 2 * y
mu2 = gp.predict(y2, t, return_cov=False)
assert not np.array_equal(mu0, mu2), \
"Different training data must give different predictions " \
"(problem with GP cache)."
a0 = gp._alpha
gp.kernel[0] += 0.1
gp.recompute()
gp._compute_alpha(y2, True)
a1 = gp._alpha
assert not np.allclose(a0, a1), \
"Different kernel parameters must give different alphas " \
"(problem with GP cache)."
mu, cov = gp.predict(y2, t)
_, var = gp.predict(y2, t, return_var=True)
assert np.allclose(np.diag(cov), var), \
"The predictive variance must be equal to the diagonal of the " \
"predictive covariance."
class GeorgeGP(object):
def __init__(self, kernel):
self.kernel = kernel
self._gp = GP(kernel._k)
self._y = None ## Cached inputs
self._x = None ## Cached values
self._dirty = True ## Flag telling if the arrays are up to date
@property
def is_dirty(self):
return self._dirty
def set_dirty(self, is_dirty=True):
self._dirty = is_dirty
def set_pv(self, pv=None):
if pv is not None and not array_equal(pv, self.kernel._pv):
self.kernel.set_pv(pv)
self._gp.kernel = self.kernel._k
self.set_dirty()
def set_inputs(self, x=None):
if x is not None and not array_equal(x, self._x):
self._x = x
self.set_dirty()
def _covariance_matrix(self, x1, x2=None, pv=None, separate=False):
self.set_pv(pv)
if separate:
return (self.kernel._k1.value(x1, x2),
self.kernel._k2.value(x1, x2))
else:
return self.kernel._k.value(x1, x2)
def compute(self, x=None, pv=None):
self.set_pv(pv)
self.set_inputs(x)
if self.is_dirty:
self._gp.compute(self._x, yerr=self.kernel._pm[-1], sort=False)
self.set_dirty(False)
def negll(self, pv, y=None):
y = y if y is not None else self._y
self.compute(self._x, pv)
return -self._gp.lnlikelihood(y)
def predict(self, x, mean_only=True):
return self._gp.predict(self._y, x, mean_only=mean_only)
def predict_components(self, pv, y, x1, x2=None):
self.compute(x1, pv)
b = self._gp.solver.apply_inverse(y)
K1 = self.kernel._k1.value(x1, x2)
K2 = self.kernel._k2.value(x1, x2)
mu_time = dot(K1,b)
mu_pos = dot(K2,b)
return mu_time, mu_pos
class GeorgeGP(object):
def __init__(self, kernel):
self.kernel = kernel
self._gp = GP(kernel._k)
self._y = None ## Cached inputs
self._x = None ## Cached values
self._dirty = True ## Flag telling if the arrays are up to date
@property
def is_dirty(self):
return self._dirty
def set_dirty(self, is_dirty=True):
self._dirty = is_dirty
def set_pv(self, pv=None):
if pv is not None and not array_equal(pv, self.kernel._pv):
self.kernel.set_pv(pv)
self._gp.kernel = self.kernel._k
self.set_dirty()
def set_inputs(self, x=None):
if x is not None and not array_equal(x, self._x):
self._x = x
self.set_dirty()
def _covariance_matrix(self, x1, x2=None, pv=None, separate=False):
self.set_pv(pv)
if separate:
return (self.kernel._k1.value(x1,
x2), self.kernel._k2.value(x1, x2))
else:
return self.kernel._k.value(x1, x2)
def compute(self, x=None, pv=None):
self.set_pv(pv)
self.set_inputs(x)
if self.is_dirty:
self._gp.compute(self._x, yerr=self.kernel._pm[-1], sort=False)
self.set_dirty(False)
def negll(self, pv, y=None):
y = y if y is not None else self._y
self.compute(self._x, pv)
return -self._gp.lnlikelihood(y)
def predict(self, x, mean_only=True):
return self._gp.predict(self._y, x, mean_only=mean_only)
def predict_components(self, pv, y, x1, x2=None):
self.compute(x1, pv)
b = self._gp.solver.apply_inverse(y)
K1 = self.kernel._k1.value(x1, x2)
K2 = self.kernel._k2.value(x1, x2)
mu_time = dot(K1, b)
mu_pos = dot(K2, b)
return mu_time, mu_pos
def test_predict_single(solver, seed=1234, N=201, yerr=0.1):
np.random.seed(seed)
# Set up the solver.
kernel = 1.0 * kernels.ExpSquaredKernel(0.5)
kwargs = dict()
if solver == HODLRSolver:
kwargs["tol"] = 1e-8
gp = GP(kernel, solver=solver, **kwargs)
x = np.sort(np.random.rand(N))
y = gp.sample(x)
gp.compute(x, yerr=yerr)
mu0, var0 = gp.predict(y, [0.0], return_var=True)
mu, var = gp.predict(y, [0.0, 1.0], return_var=True)
_, cov = gp.predict(y, [0.0, 1.0])
assert np.allclose(mu0, mu[0])
assert np.allclose(var0, var[0])
assert np.allclose(var0, cov[0, 0])
def test_prediction(solver, seed=42):
"""Basic sanity checks for GP regression."""
np.random.seed(seed)
kernel = kernels.ExpSquaredKernel(1.0)
kwargs = dict()
if solver == HODLRSolver:
kwargs["tol"] = 1e-8
gp = GP(kernel, solver=solver, white_noise=0.0, **kwargs)
x0 = np.linspace(-10, 10, 500)
x = np.sort(np.random.uniform(-10, 10, 300))
gp.compute(x)
y = np.sin(x)
mu, cov = gp.predict(y, x0)
Kstar = gp.get_matrix(x0, x)
K = gp.get_matrix(x)
K[np.diag_indices_from(K)] += 1.0
mu0 = np.dot(Kstar, np.linalg.solve(K, y))
print(np.abs(mu - mu0).max())
assert np.allclose(mu, mu0)
def plotpred_QP(p, t, y):
kern, sig = kern_QP(p)
gp = GP(kern)
yerr = np.ones(len(y)) * sig
gp.compute(t, yerr)
mu, cov = gp.predict(y, t)
sigma = np.diag(cov)
sigma = np.sqrt(sigma**2 + yerr**2)
pl.fill_between(t, mu + 2 * sigma, mu - 2 * sigma, \
color='c', alpha=0.3)
pl.plot(t, mu, color='c', lw=2)
nper = (len(p) - 1) / 4
# if nper > 1:
# cols = ['c','m','y','k']
# for i in range(nper):
# p1 = np.append(p[i*4:i*4+4], p[-1])
# k1, sig = kern_QP(p1)
# b = gp.solver.apply_inverse(y)
# X = np.transpose([t])
# K1 = k1.value(t, t)
# mu1 = np.dot(K1, b)
# col = np.roll(cols, -i)[0]
# pl.plot(t, mu, color = col, lw = 2)
return
def run(self):
gp = GP(self._kernel)
gp.compute(self._x)
y = self._y
pipe = self._out_pipe
for cmd, args, kwargs in iter(pipe.recv, None):
if cmd == 'predict':
result = gp.predict(y, *args, **kwargs)
if len(result) == 2:
# only return the diagonal of the covariance matrix
result = result[0], result[1].diagonal()
elif cmd == 'get_kernel_pars':
result = gp.kernel.pars
elif cmd == 'set_kernel_pars':
gp.kernel.pars = args[0]
result = None
elif cmd == 'train':
prior, nstarts, verbose = args
# define function for negative log-likelihood and its gradient
def nll(vector, bad_return=(1e30, np.zeros(len(gp.kernel)))):
# prevent exp overflow
if np.any(vector > 100.):
return bad_return
gp.kernel.vector = vector
ll = gp.lnlikelihood(y, quiet=True)
if not np.isfinite(ll):
return bad_return
grad = gp.grad_lnlikelihood(y, quiet=True)
return -ll, -grad
if verbose:
print(self.name, 'starting training')
# sample random initial positions from prior
# run optimization for each
result = tuple(
optimize.minimize(nll, x0, jac=True, **kwargs)
for x0 in np.log(prior.rvs(nstarts))
)
if verbose:
print(self.name, 'training complete')
# Print a table of results.
# Since results are sure to repeat,
# group them and output a row for each group:
# number ll *hyperpars
for nll, group in itertools.groupby(
sorted(result, key=lambda r: r.fun),
key=lambda r: round(r.fun, 2)
):
for n, r in enumerate(group, start=1):
pass
print(' ', n, -nll, _format_number_list(*np.exp(r.x)))
# set hyperparameters to opt result with best likelihood
gp.kernel.vector = min(result, key=lambda r: r.fun).x
else:
result = ValueError('Unknown command: {}.'.format(cmd))
pipe.send(result)
