def test_gaussian_kernel_dx_component_equals_grad():
D = 4
x = np.random.randn(D)
y = np.random.randn(D)
sigma = 0.5
grad = gaussian_kernel_grad(x, np.atleast_2d(y), sigma)[0]
for i in range(D):
dxi = gaussian_kernel_dx_component(x, y, i, sigma)
assert_allclose(grad[i], dxi)
def grad(self, x):
assert_array_shape(x, ndim=1, dims={0: self.D})
# now x is of shape (D,)
# assume M datapoints in x
Kxx = 1 # should be a scalar: Kxx = exp(-(x-x)**2 / self.sigma) = 1
KxX = gaussian_kernel(x[np.newaxis, :], self.X, sigma=self.sigma) # shape (1, K)
xX_grad = gaussian_kernel_grad(x, self.X, self.sigma) # should be shape (K, D)
tmp = np.dot(KxX, self.K_inv) # should be of shape (1, K)
A = Kxx + self.lmbda - np.sum(tmp * KxX) # should be a scalar
B = np.dot(KxX, self.X_grad) - np.dot(tmp + 1, xX_grad) # shape (1, D)
gradient = -B[0] / A # shape (D,)
return gradient
def grad(self, x):
if x.ndim == 1:
g = np.sum(gaussian_kernel_grad(x, self.X, sigma=self.bandwidth),
axis=0) / np.sum(gaussian_kernel(
x[None, :], self.X, sigma=self.bandwidth),
axis=-1)
return g
else:
grads = []
for i in xrange(x.shape[0]):
g_i = self.grad(x[i])
grads.append(g_i)
return np.asarray(grads)
def log_pdf_naive(x, X, sigma, alpha, beta):
N, D = X.shape
xi = 0
betasum = 0
for a in range(N):
x_a = np.atleast_2d(X[a, :])
gradient_x_xa = np.squeeze(gaussian_kernel_grad(x, x_a, sigma))
xi_grad = np.squeeze(gaussian_kernel_dx_dx(x, x_a, sigma))
for i in range(D):
xi += xi_grad[i] / N
betasum += gradient_x_xa[i] * beta[a, i]
return alpha * xi + betasum
def test_gaussian_kernel_grad_theano_result_equals_manual():
if not theano_available:
raise SkipTest("Theano not available")
D = 3
x = np.random.randn(D)
y = np.random.randn(D)
sigma = 2.
grad = gaussian_kernel_grad_theano(x, y, sigma)
grad_manual = gaussian_kernel_grad(x, y[np.newaxis, :], sigma)[0]
print grad_manual
print grad
assert_allclose(grad, grad_manual)
def test_gaussian_kernel_grad_theano_result_equals_manual():
if not theano_available:
raise SkipTest("Theano not available")
D = 3
x = np.random.randn(D)
y = np.random.randn(D)
sigma = 2.
grad = gaussian_kernel_grad_theano(x, y, sigma)
grad_manual = gaussian_kernel_grad(x, y[np.newaxis, :], sigma)[0]
print grad_manual
print grad
assert_allclose(grad, grad_manual)
def log_pdf(x, basis, sigma, alpha, beta):
m, D = basis.shape
assert_array_shape(x, ndim=1, dims={0: D})
SE_dx_dx_l = lambda x, y: gaussian_kernel_dx_dx(x, y.reshape(1, -1), sigma)
SE_dx_l = lambda x, y: gaussian_kernel_grad(x, y.reshape(1, -1), sigma)
xi = 0
betasum = 0
for a in range(m):
x_a = basis[a]
xi += np.sum(SE_dx_dx_l(x, x_a)) / m
gradient_x_xa = np.squeeze(SE_dx_l(x, x_a))
betasum += np.dot(gradient_x_xa, beta[a, :])
return np.float(alpha * xi + betasum)
def grad(self, x):
assert_array_shape(x, ndim=1, dims={0: self.D})
k = gaussian_kernel_grad(x, self.X, self.sigma)
return np.dot(self.alpha, k)
def grad(self, x):
assert_array_shape(x, ndim=1, dims={0: self.D})
k = gaussian_kernel_grad(x, self.X, self.sigma)
return np.dot(self.alpha, k)
def grad(self, x):
g = np.sum(gaussian_kernel_grad(x, self.X, sigma=self.bandwidth),
axis=0) / np.sum(gaussian_kernel(
x[None, :], self.X, sigma=self.bandwidth),
axis=-1)
return g
