def run(N=50, K=5, D=2):
# Generate data
N1 = np.floor(0.5*N)
N2 = N - N1
y = np.vstack([np.random.normal(0, 0.5, size=(N1,D)),
np.random.normal(10, 0.5, size=(N2,D))])
# Construct model
Q = gaussianmix_model(N,K,D)
# Observe data
Q['Y'].observe(y)
# Run inference
Q.update(repeat=30)
# Run predictive model
zh = nodes.Categorical(Q['alpha'], name='zh')
Yh = nodes.Mixture(zh, nodes.Gaussian, Q['X'], Q['Lambda'], name='Yh')
zh.update()
# Plot predictive pdf
N1 = 400
N2 = 400
x1 = np.linspace(-3, 15, N1)
x2 = np.linspace(-3, 15, N2)
xh = misc.grid(x1, x2)
lpdf = Yh.integrated_logpdf_from_parents(xh, 0)
pdf = np.reshape(np.exp(lpdf), (N2,N1))
plt.clf()
plt.contourf(x1, x2, pdf, 100)
plt.scatter(y[:,0], y[:,1])
print('integrated pdf:', np.sum(pdf)*(18*18)/(N1*N2))
def gaussianmix_model(N, K, D):
# N = number of data vectors
# K = number of clusters
# D = dimensionality
# Construct the Gaussian mixture model
# K prior weights (for components)
alpha = nodes.Dirichlet(1 * np.ones(K), name='alpha')
# N K-dimensional cluster assignments (for data)
z = nodes.Categorical(alpha, plates=(N, ), name='z')
# K D-dimensional component means
X = nodes.Gaussian(np.zeros(D),
0.01 * np.identity(D),
plates=(K, ),
name='X')
# K D-dimensional component covariances
Lambda = nodes.Wishart(D,
0.01 * np.identity(D),
plates=(K, ),
name='Lambda')
# N D-dimensional observation vectors
Y = nodes.Mixture(nodes.Gaussian)(z, X, Lambda, plates=(N, ), name='Y')
# TODO: Plates should be learned automatically if not given (it
# would be the smallest shape broadcasted from the shapes of the
# parents)
return (Y, X, Lambda, z, alpha)
def gaussianmix_model(N, K, D, covariance='full'):
# N = number of data vectors
# K = number of clusters
# D = dimensionality
# Construct the Gaussian mixture model
# K prior weights (for components)
alpha = nodes.Dirichlet(1e-3*np.ones(K),
name='alpha')
# N K-dimensional cluster assignments (for data)
z = nodes.Categorical(alpha,
plates=(N,),
name='z')
# K D-dimensional component means
X = nodes.GaussianARD(0, 1e-3,
shape=(D,),
plates=(K,),
name='X')
if covariance.lower() == 'full':
# K D-dimensional component covariances
Lambda = nodes.Wishart(D, 0.01*np.identity(D),
plates=(K,),
name='Lambda')
# N D-dimensional observation vectors
Y = nodes.Mixture(z, nodes.Gaussian, X, Lambda, plates=(N,), name='Y')
elif covariance.lower() == 'diagonal':
# Inverse variances
Lambda = nodes.Gamma(1e-3, 1e-3, plates=(K, D), name='Lambda')
# N D-dimensional observation vectors
Y = nodes.Mixture(z, nodes.GaussianARD, X, Lambda, plates=(N,), name='Y')
elif covariance.lower() == 'isotropic':
# Inverse variances
Lambda = nodes.Gamma(1e-3, 1e-3, plates=(K, 1), name='Lambda')
# N D-dimensional observation vectors
Y = nodes.Mixture(z, nodes.GaussianARD, X, Lambda, plates=(N,), name='Y')
z.initialize_from_random()
return VB(Y, X, Lambda, z, alpha)
def run(N=50, K=5, D=2):
#plt.ion()
#17,31
#np.random.seed(31)
# Generate data
N1 = np.floor(0.5 * N)
N2 = N - N1
y = np.vstack([
np.random.normal(0, 0.5, size=(N1, D)),
np.random.normal(10, 0.5, size=(N2, D))
])
# Construct model
(Y, X, Lambda, z, alpha) = gaussianmix_model(N, K, D)
# Initialize nodes (from prior and randomly)
alpha.initialize_from_prior()
z.initialize_from_prior()
Lambda.initialize_from_parameters(D, 10 * np.identity(D))
X.initialize_from_prior()
X.initialize_from_parameters(X.random(), np.identity(D))
## X.initialize_from_parameters(np.random.permutation(y)[:K],
## 0.01*np.identity(D))
#X.initialize_from_random()
# Initialize means by selecting random data points
#X.initialize_from_value(np.random.permutation(y)[:K])
#return
#X.initialize_random_mean()
#Y.initialize()
## X.show()
## return
# Data with missing values
## mask = np.random.rand(M,N) < 0.4 # randomly missing
## mask[:,20:40] = False # gap missing
# Y.observe(y, mask)
## alpha.show()
## Lambda.show()
## z.show()
X.show()
#return
Y.observe(y)
## z.update()
## X.update()
## alpha.update()
## X.show()
## alpha.show()
#Lambda.show()
#return
## X.show()
## Lambda.show()
## z.update()
## z.show()
## return
# Inference loop.
maxiter = 30
L_X = np.zeros(maxiter)
L_Lambda = np.zeros(maxiter)
L_alpha = np.zeros(maxiter)
L_z = np.zeros(maxiter)
L_Y = np.zeros(maxiter)
L = np.zeros(maxiter)
L_last = -np.inf
for i in range(maxiter):
t = time.clock()
# Update nodes
z.update()
alpha.update()
X.update()
Lambda.update()
#Y.show()
#z.show()
# Compute lower bound
L_X[i] = X.lower_bound_contribution()
L_Lambda[i] = Lambda.lower_bound_contribution()
L_alpha[i] = alpha.lower_bound_contribution()
L_z[i] = z.lower_bound_contribution()
L_Y[i] = Y.lower_bound_contribution()
L[i] = L_X[i] + L_Lambda[i] + L_alpha[i] + L_z[i] + L_Y[i]
#print('terms:', L_X[i], L_Lambda[i], L_alpha[i], L_z[i], L_Y[i])
# Check convergence
print("Iteration %d: loglike=%e (%.3f seconds)" %
(i + 1, L[i], time.clock() - t))
if L_last - L[i] > 1e-6:
L_diff = (L_last - L[i])
print(
"Lower bound decreased %e! Bug somewhere or numerical inaccuracy?"
% L_diff)
#raise Exception("Lower bound decreased %e! Bug somewhere or numerical inaccuracy?" % L_diff)
if L[i] - L_last < 1e-12:
print("Converged.")
#break
L_last = L[i]
# Predictive stuff
zh = nodes.Categorical(alpha, name='zh')
Yh = nodes.Mixture(nodes.Gaussian)(zh, X, Lambda, name='Yh')
# TODO/FIXME: Messages to parents should use the masks such that
# children don't need to be initialized!
zh.initialize_from_prior()
Yh.initialize_from_prior()
zh.update()
#zh.show()
N1 = 400
N2 = 400
x1 = np.linspace(-3, 15, N1)
x2 = np.linspace(-3, 15, N2)
xh = utils.grid(x1, x2)
lpdf = Yh.integrated_logpdf_from_parents(xh, 0)
pdf = np.reshape(np.exp(lpdf), (N2, N1))
#print(pdf)
#plt.clf()
plt.clf()
#plt.imshow(x1, x2, pdf)
plt.contourf(x1, x2, pdf, 100)
plt.scatter(y[:, 0], y[:, 1])
print('integrated pdf:', np.sum(pdf) * (18 * 18) / (N1 * N2))
#return
X.show()
alpha.show()
plt.show()