def experiment_kiss(dataset=PUMADYN32NM, m=100, proj_d=2, cov='covSEard', standardize=True, proj=None):
assert proj in {None, 'norm', 'orth'}
train_x, train_y, test_x, test_y = load_dataset(dataset)
if standardize:
scaler = StandardScaler()
train_x = scaler.fit_transform(train_x)
test_x = scaler.transform(test_x)
n, d = train_x.shape
print 'Train KISS with {} data points and {} dimension'.format(n, d)
# get GP functionality
gp = GaussianProcess()
# subtract mean
train_y -= np.mean(train_y)
test_y -= np.mean(train_y)
# projection matrix
P = np.random.normal(size=(proj_d, d))
# initialization
hyp_lik = float(0.5 * np.log(np.var(train_y) / 4))
if cov == 'covSEard':
init_x = np.dot(train_x, P.T)
init_ell = np.log((np.max(init_x, axis=0) - np.min(init_x, axis=0)) / 2)
hyp_cov = np.append(init_ell, [0.5 * np.log(np.var(train_y))])
else:
hyp_cov = np.asarray([np.log(5), 0.5 * np.log(np.var(train_y))])
hyp_old = {'mean': [], 'lik': hyp_lik, 'cov': hyp_cov, 'proj': P}
opt = {'cg_maxit': 500, 'cg_tol': 1e-5}
if proj is not None:
opt['proj'] = proj
hyp = gp.train_kiss(train_x, train_y.reshape(-1, 1), k=m, hyp=hyp_old, opt=opt, n_iter=100)
test_mean, test_var = gp.predict_kiss(train_x, train_y.reshape(-1, 1), k=m, xstar=test_x, opt=opt, hyp=hyp, cov=cov)
print 'KISS error:'
print_error(test_y, test_mean)
def experiment1D():
gp = GaussianProcess()
# setup data
n = 500
m = 50
f = lambda x: np.sin(x) * np.exp(-x**2 / 50)
X = np.random.uniform(-10, 10, size=n)
X = np.sort(X)
y = f(X) + np.random.normal(0, 1, size=n)
y -= np.mean(y)
x_min, x_max = np.min(X), np.max(X)
U = np.linspace(x_min, x_max, m).reshape(-1, 1)
X = X.reshape(-1, 1)
hyp_cov = np.asarray([np.log(1), np.log(2)])
hyp_lik = float(np.log(1))
hyp_old = {'mean': [], 'lik': hyp_lik, 'cov': hyp_cov}
hyp = gp.train_exact(X, y.reshape(-1, 1), hyp_old)
hyp_cov = hyp['cov'][0]
sigmasq = np.exp(2 * hyp['lik'])
kernel = SEiso()
distill = Distillation(X=X,
y=y,
U=U,
kernel=kernel,
hyp=hyp_cov,
num_iters=10,
eta=5e-4,
sigmasq=sigmasq,
width=3,
use_kmeans=True,
optimizer='sgd')
distill.grad_descent()
distill.precompute(use_true_K=False)
xx = np.linspace(x_min, x_max, 2 * n)
mm_true, vv_true = gp.predict_exact(X,
y.reshape(-1, 1),
xx.reshape(-1, 1),
hyp=hyp)
mm = []
vv = []
opt = {'cg_maxit': 500, 'cg_tol': 1e-5}
k = n / 2
hyp = gp.train_kiss(X, y.reshape(-1, 1), k, hyp=hyp_old, opt=opt)
mm_kiss, vv_kiss = gp.predict_kiss(X,
y.reshape(-1, 1),
xx.reshape(-1, 1),
k,
hyp=hyp,
opt=opt)
for xstar in xx:
xstar = np.asarray([xstar])
mstar, vstar = distill.predict(xstar, width=3)
vv.append(vstar)
mm.append(mstar)
mm = np.asarray(mm).flatten()
vv = np.asarray(vv).flatten()
mm_kiss = np.asarray(mm_kiss).flatten()
vv_kiss = np.asarray(vv_kiss).flatten()
plt.fill_between(xx,
mm - np.sqrt(vv) * 2,
mm + np.sqrt(vv) * 2,
color='gray',
alpha=.5)
plt.plot(xx, mm_true, color='y', lw=3, label='exact mean')
plt.plot(xx, mm, color='r', lw=3, label='distill mean', ls='dotted')
plt.plot(xx, mm_kiss, color='g', lw=3, label='kiss mean', ls=':')
plt.plot(xx, f(xx), lw=3, label='true value', ls='dashed')
plt.scatter(X, y, color='m', label='train data', marker='+')
plt.xlim([x_min, x_max])
plt.legend()
plt.show()
plt.plot(xx, vv_kiss, color='g', lw=3, label='kiss var', ls=':')
plt.plot(xx, vv_true, color='y', lw=3, label='exact var')
plt.plot(xx, vv, color='r', lw=3, label='distill var', ls='dotted')
plt.xlim([x_min, x_max])
plt.legend()
plt.show()
