def build_kernel(state: TuningJobState,
do_warping: bool = False) -> KernelFunction:
dims, warping_ranges = dimensionality_and_warping_ranges(state.hp_ranges)
kernel = Matern52(dims, ARD=True)
if do_warping:
return WarpedKernel(kernel=kernel,
warping=Warping(dims, warping_ranges))
else:
return kernel
def test_gp_regression_with_warping():
def f(x):
return np.sin(3 * np.log(x))
np.random.seed(7)
L, U = -5., 12.
input_range = (2.**L, 2.**U)
x_train = np.sort(2.**np.random.uniform(L, U, 250))
x_test = np.sort(2.**np.random.uniform(L, U, 500))
y_train = f(x_train)
y_test = f(x_test)
# to mx.nd
y_train_mx_nd = mx.nd.array(y_train)
x_train_mx_nd = mx.nd.array(x_train)
x_test_mx_nd = mx.nd.array(x_test)
kernels = [
Matern52(dimension=1),
WarpedKernel(kernel=Matern52(dimension=1),
warping=Warping(dimension=1,
index_to_range={0: input_range}))
]
models = [
GaussianProcessRegression(kernel=k, random_seed=0) for k in kernels
]
train_errors, test_errors = [], []
for model in models:
model.fit(x_train_mx_nd, y_train_mx_nd)
mu_train, var_train = model.predict(x_train_mx_nd)[0]
mu_test, var_test = model.predict(x_test_mx_nd)[0]
# back to np.array
mu_train = mu_train.asnumpy()
mu_test = mu_test.asnumpy()
# var_train = var_train.asnumpy()
# var_test = var_test.asnumpy()
train_errors.append(np.mean(np.abs((mu_train - y_train))))
test_errors.append(np.mean(np.abs((mu_test - y_test))))
# The two models have similar performance on training points
np.testing.assert_almost_equal(train_errors[0], train_errors[1], decimal=4)
# As expected, the model with warping largely outperforms the model without
assert test_errors[1] < 0.1 * test_errors[0]
def test_set_gp_hps():
mean = ScalarMeanFunction()
kernel = Matern52(dimension=1)
warping = Warping(dimension=1, index_to_range={0: (-4., 4.)})
warped_kernel = WarpedKernel(kernel=kernel, warping=warping)
likelihood = MarginalLikelihood(kernel=warped_kernel,
mean=mean,
initial_noise_variance=1e-6)
likelihood.initialize(ctx=mx.cpu(), force_reinit=True)
likelihood.hybridize()
hp_values = np.array([1e-2, 1.0, 0.5, 0.3, 0.2, 1.1])
_set_gp_hps(hp_values, likelihood)
np.testing.assert_array_almost_equal(hp_values, _get_gp_hps(likelihood))
def test_get_gp_hps():
mean = ScalarMeanFunction()
kernel = Matern52(dimension=1)
warping = Warping(dimension=1, index_to_range={0: (-4., 4.)})
warped_kernel = WarpedKernel(kernel=kernel, warping=warping)
likelihood = MarginalLikelihood(kernel=warped_kernel,
mean=mean,
initial_noise_variance=1e-6)
likelihood.initialize(ctx=mx.cpu(), force_reinit=True)
likelihood.hybridize()
hp_values = _get_gp_hps(likelihood)
# the oder of hps are noise, mean, covariance scale, bandwidth, warping a, warping b
np.testing.assert_array_almost_equal(
hp_values, np.array([1e-6, 0.0, 1.0, 1.0, 1.0, 1.0]))
def resource_kernel_factory(
name: str, kernel_x: KernelFunction, mean_x: gluon.HybridBlock,
max_metric_value: float) -> (KernelFunction, gluon.HybridBlock):
"""
Given kernel function kernel_x and mean function mean_x over config x,
create kernel and mean functions over (x, r), where r is the resource
attribute (nonnegative scalar, usually in [0, 1]).
:param name: Selects resource kernel type
:param kernel_x: Kernel function over configs x
:param mean_x: Mean function over configs x
:return: res_kernel, res_mean, both over (x, r)
"""
if name == 'matern52':
res_kernel = Matern52(dimension=kernel_x.dimension + 1, ARD=True)
res_mean = mean_x
elif name == 'matern52-res-warp':
# Warping on resource dimension (last one)
dim_x = kernel_x.dimension
res_warping = Warping(dimension=dim_x + 1,
index_to_range={dim_x: (0., 1.)})
res_kernel = WarpedKernel(kernel=Matern52(dimension=dim_x + 1,
ARD=True),
warping=res_warping)
res_mean = mean_x
else:
if name == 'exp-decay-sum':
delta_fixed_value = 0.0
elif name == 'exp-decay-combined':
delta_fixed_value = None
elif name == 'exp-decay-delta1':
delta_fixed_value = 1.0
else:
raise AssertionError("name = '{}' not supported".format(name))
res_kernel = ExponentialDecayResourcesKernelFunction(
kernel_x,
mean_x,
gamma_init=0.5 * max_metric_value,
delta_fixed_value=delta_fixed_value,
max_metric_value=max_metric_value)
res_mean = ExponentialDecayResourcesMeanFunction(kernel=res_kernel)
return res_kernel, res_mean
def build_kernel():
return WarpedKernel(kernel=Matern52(dimension=1),
warping=Warping(dimension=1,
index_to_range={0: (-4., 4.)}))