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[ssgplvm] implement IBP prior

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Zhenwen Dai 2015-05-21 14:18:32 +01:00
parent 21a39ffb87
commit afa0621488
4 changed files with 34 additions and 31 deletions
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54
GPy/models/ss_gplvm.py
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@ -7,7 +7,7 @@ from ..core.sparse_gp_mpi import SparseGP_MPI
from .. import kern
from ..core.parameterization import Param
from ..likelihoods import Gaussian
from ..core.parameterization.variational import SpikeAndSlabPrior, SpikeAndSlabPosterior
from ..core.parameterization.variational import SpikeAndSlabPrior, SpikeAndSlabPosterior,VariationalPrior
from ..inference.latent_function_inference.var_dtc_parallel import update_gradients, VarDTC_minibatch
from ..kern._src.psi_comp.ssrbf_psi_gpucomp import PSICOMP_SSRBF_GPU
@ -15,13 +15,13 @@ class IBPPosterior(SpikeAndSlabPosterior):
'''
The SpikeAndSlab distribution for variational approximations.
'''
def __init__(self, means, variances, binary_prob, tau, name='latent space'):
def __init__(self, means, variances, binary_prob, tau=None, name='latent space'):
"""
binary_prob : the probability of the distribution on the slab part.
"""
from ..core.parameterization.transformations import Logexp, __fixed__
super(IBPPosterior, self).__init__(means, variances, name)
self.tau = Param("tau",SpikeAndSlabPosterior, Logexp)
from ..core.parameterization.transformations import Logexp
super(IBPPosterior, self).__init__(means, variances, binary_prob, group_spike=True, name=name)
self.tau = Param("tau_", np.ones((self.gamma_group.shape[0],2)), Logexp())
self.link_parameter(self.tau)
def set_gradients(self, grad):
@ -35,7 +35,7 @@ class IBPPosterior(SpikeAndSlabPosterior):
dc['mean'] = self.mean[s]
dc['variance'] = self.variance[s]
dc['binary_prob'] = self.binary_prob[s]
dc['tau'] = self.tau[s]
dc['tau'] = self.tau
dc['parameters'] = copy.copy(self.parameters)
n.__dict__.update(dc)
n.parameters[dc['mean']._parent_index_] = dc['mean']
@ -53,16 +53,17 @@ class IBPPosterior(SpikeAndSlabPosterior):
else:
return super(IBPPosterior, self).__getitem__(s)
class IBPPrior(SpikeAndSlabPrior):
class IBPPrior(VariationalPrior):
def __init__(self, input_dim, alpha =2., name='IBPPrior', **kw):
super(SpikeAndSlabPrior, self).__init__(name=name, **kw)
super(IBPPrior, self).__init__(name=name, **kw)
from ..core.parameterization.transformations import Logexp, __fixed__
self.input_dim = input_dim
self.variance = 1.
self.alpha = Param('alpha', alpha, __fixed__)
self.link_parameter(self.alpha)
def KL_divergence(self, variational_posterior):
mu, S, gamma, tau = variational_posterior.mean.values, variational_posterior.variance.values, variational_posterior.gamma.values, variational_posterior.tau.values
mu, S, gamma, tau = variational_posterior.mean.values, variational_posterior.variance.values, variational_posterior.gamma_group.values, variational_posterior.tau.values
var_mean = np.square(mu)/self.variance
var_S = (S/self.variance - np.log(S))
@ -77,18 +78,17 @@ class IBPPrior(SpikeAndSlabPrior):
return part1+part2
def update_gradients_KL(self, variational_posterior):
mu, S, gamma, tau = variational_posterior.mean.values, variational_posterior.variance.values, variational_posterior.gamma.values, variational_posterior.tau.values
mu, S, gamma, tau = variational_posterior.mean.values, variational_posterior.variance.values, variational_posterior.gamma_group.values, variational_posterior.tau.values
variational_posterior.binary_prob.gradient -= ((np.square(mu)+S)/self.variance-np.log(S)+np.log(self.variance)-1.)/2.
mu.gradient -= gamma*mu/self.variance
S.gradient -= (1./self.variance - 1./S) * gamma /2.
if self.learnPi:
if len(self.pi)==1:
self.pi.gradient = (gamma/self.pi - (1.-gamma)/(1.-self.pi)).sum()
elif len(self.pi.shape)==1:
self.pi.gradient = (gamma/self.pi - (1.-gamma)/(1.-self.pi)).sum(axis=0)
else:
self.pi[idx].gradient = (gamma/self.pi[idx] - (1.-gamma)/(1.-self.pi[idx]))
variational_posterior.mean.gradient -= gamma*mu/self.variance
variational_posterior.variance.gradient -= (1./self.variance - 1./S) * gamma /2.
from scipy.special import digamma,polygamma
dgamma = (np.log(gamma/(1.-gamma))+ digamma(tau[:,1])-digamma(tau[:,0]))/mu.shape[0]
variational_posterior.binary_prob.gradient -= dgamma+((np.square(mu)+S)/self.variance-np.log(S)+np.log(self.variance)-1.)/2.
ad = self.alpha/self.input_dim
common = (ad+2-tau[:,0]-tau[:,1])*polygamma(1,tau.sum(axis=1))
variational_posterior.tau.gradient[:,0] = -((tau[:,0]-gamma-ad)*polygamma(1,tau[:,0])+common)
variational_posterior.tau.gradient[:,1] = -((tau[:,1]+gamma-2)*polygamma(1,tau[:,1])+common)
class SSGPLVM(SparseGP_MPI):
"""
@ -103,7 +103,7 @@ class SSGPLVM(SparseGP_MPI):
"""
def __init__(self, Y, input_dim, X=None, X_variance=None, Gamma=None, init='PCA', num_inducing=10,
Z=None, kernel=None, inference_method=None, likelihood=None, name='Spike_and_Slab GPLVM', group_spike=False, mpi_comm=None, pi=None, learnPi=False,normalizer=False, **kwargs):
Z=None, kernel=None, inference_method=None, likelihood=None, name='Spike_and_Slab GPLVM', group_spike=False, IBP=False, alpha=2., tau=None, mpi_comm=None, pi=None, learnPi=False,normalizer=False, **kwargs):
self.group_spike = group_spike
@ -144,10 +144,14 @@ class SSGPLVM(SparseGP_MPI):
if pi is None:
pi = np.empty((input_dim))
pi[:] = 0.5
self.variational_prior = SpikeAndSlabPrior(pi=pi,learnPi=learnPi, group_spike=group_spike) # the prior probability of the latent binary variable b
X = SpikeAndSlabPosterior(X, X_variance, gamma, group_spike=group_spike)
if IBP:
self.variational_prior = IBPPrior(input_dim=input_dim, alpha=alpha)
X = IBPPosterior(X, X_variance, gamma, tau=tau)
else:
self.variational_prior = SpikeAndSlabPrior(pi=pi,learnPi=learnPi, group_spike=group_spike) # the prior probability of the latent binary variable b
X = SpikeAndSlabPosterior(X, X_variance, gamma, group_spike=group_spike)
super(SSGPLVM,self).__init__(X, Y, Z, kernel, likelihood, variational_prior=self.variational_prior, inference_method=inference_method, name=name, mpi_comm=mpi_comm, normalizer=normalizer, **kwargs)
self.link_parameter(self.X, index=0)