def PMCMCstep(self, iteration):
#progressbar(iteration / (self.nbiterations - 1))
progressbar(iteration / (self.nbiterations - 1), text = " acceptance rate: %.3f" % \
(sum(self.acceptations[0:iteration]) / iteration))
#print "iteration %i, acceptance rate until now: %.3f" % (iteration, sum(self.acceptations[0:iteration]) / iteration)
if (random.uniform(size = 1) < self.proposalmixtureweights[0]):
transformedthetastar = self.modeltheta.proposal(self.transformedtheta[:, newaxis], self.fixedproposalcovmatrix)[:, 0]
else:
transformedthetastar = self.modeltheta.proposal(self.transformedtheta[:, newaxis], self.adaptiveproposalcovmatrix)[:, 0]
thetastar = self.modeltheta.untransform(transformedthetastar[:,newaxis])[:,0]
proposedSIRs = ParallelSIRs(self.Nx, thetastar[:, newaxis], self.observations, self.modelx)
proposedSIRs.first_step()
proposedSIRs.next_steps()
proposedloglike = proposedSIRs.getTotalLogLike()[0]
proposedlogomega = proposedloglike + self.modeltheta.priorlogdensity(transformedthetastar)
currentlogomega = self.totalLogLike + self.modeltheta.priorlogdensity(self.transformedtheta)
acceptation = (log(random.uniform(size = 1)) < (proposedlogomega - currentlogomega))
# if not(acceptation):
# print "\nproposed loglikelihood:", proposedloglike
# print "\ncurrent loglikelihood:", self.totalLogLike
# print "\naccept:", acceptation
if acceptation:
self.theta = thetastar.copy()
self.transformedtheta = transformedthetastar.copy()
self.totalLogLike = proposedloglike.copy()
self.chain[:, iteration] = self.theta.copy()
self.transformedchain[:, iteration] = self.transformedtheta.copy()
if iteration > 10:
self.adaptiveproposalcovmatrix = (5.6644 / self.thetadim) * cov(self.transformedchain[:, 1:iteration])
#print "\n", self.adaptiveproposalcovmatrix
self.loglikechain[iteration] = self.totalLogLike
self.acceptations[iteration] = acceptation
def __init__(self, model, algorithmparameters, autoinit = True):
# get the model:
self.modelx = model["modelx"]
self.modeltheta = model["modeltheta"]
self.observations = model["observations"]
self.Nx = algorithmparameters["N"]
self.nbiterations = algorithmparameters["nbiterations"]
#
self.theta = self.modeltheta.priorgenerator(1)[:,0]
self.thetadim = self.theta.shape[0]
self.transformedtheta = self.modeltheta.transform(self.theta[:, newaxis])[:,0]
self.chain = zeros((self.thetadim, self.nbiterations))
self.transformedchain = zeros((self.thetadim, self.nbiterations))
self.chain[:, 0] = self.theta.copy()
self.transformedchain[:, 0] = self.transformedtheta.copy()
#
self.acceptations = zeros(self.nbiterations)
self.fixedproposalcovmatrix = diag(repeat(0.01 / self.thetadim, self.thetadim))
self.adaptiveproposalcovmatrix = diag(repeat(5.6644 / self.thetadim, self.thetadim))
self.proposalmixtureweights = [0.5, 0.5]
currentSIRs = ParallelSIRs(self.Nx, self.theta[:, newaxis], self.observations, self.modelx)
currentSIRs.first_step()
currentSIRs.next_steps()
self.totalLogLike = currentSIRs.getTotalLogLike()[0]
self.loglikechain = zeros(self.nbiterations)
self.loglikechain[0] = self.totalLogLike
print "------------------"
print "launching adaptive PMCMC, with algorithm parameters:"
for key, element in algorithmparameters.items():
print key, ":", element
print "------------------"
if autoinit:
self.allsteps()
def PMCMCstep(self, t):
"""
Perform a PMMH move step on each theta-particle.
"""
transformedthetastar = self.modeltheta.proposal(self.transformedthetaparticles, \
self.proposalcovmatrix, hyperparameters = self.modeltheta.hyperparameters,\
proposalmean = self.proposalmean, proposalkernel = self.AP["proposalkernel"])
thetastar = self.modeltheta.untransform(transformedthetastar)
proposedSIRs = ParallelSIRs(self.Nx, thetastar,
self.observations[0:(t + 1)], self.modelx)
proposedSIRs.first_step()
proposedSIRs.next_steps()
proposedTotalLogLike = proposedSIRs.getTotalLogLike()
acceptations = zeros(self.Ntheta)
proposedpriordensityeval = apply_along_axis(func1d = self.modeltheta.priorlogdensity,\
arr = transformedthetastar, axis = 0)
proposedlogomega = proposedTotalLogLike + proposedpriordensityeval
currentlogomega = self.totalLogLike + self.priordensityeval
# if proposal kernel == "randomwalk", then nothing else needs to be computed
# since the RW is symmetric. If the proposal kernel is independent, then
# the density of the multivariate gaussian used to generate the proposals
# needs to be taken into account
if self.AP["proposalkernel"] == "randomwalk":
pass
elif self.AP["proposalkernel"] == "independent":
invSigma = linalg.inv(self.proposalcovmatrix)
def multinorm_logpdf(x):
centeredx = (x - self.proposalmean)
return -0.5 * dot(dot(centeredx, invSigma), centeredx)
proposaltermstar = apply_along_axis(func1d = multinorm_logpdf, \
arr = transformedthetastar, axis = 0)
proposedlogomega -= proposaltermstar
proposaltermcurr = apply_along_axis(func1d = multinorm_logpdf, \
arr = self.transformedthetaparticles, axis = 0)
currentlogomega -= proposaltermcurr
for i in range(self.Ntheta):
acceptations[i] = (log(random.uniform(size=1)) <
(proposedlogomega[i] - currentlogomega[i]))
if acceptations[i]:
self.transformedthetaparticles[:,
i] = transformedthetastar[:,
i].copy(
)
self.thetaparticles[:, i] = thetastar[:, i].copy()
self.totalLogLike[i] = proposedTotalLogLike[i].copy()
self.priordensityeval[i] = proposedpriordensityeval[i].copy()
self.xparticles[:, :, i] = proposedSIRs.xparticles[:, :,
i].copy()
acceptrate = sum(acceptations) / self.Ntheta
self.acceptratios.append(acceptrate)
def PMCMCstep(self, t):
"""
Perform a PMMH move step on each theta-particle.
"""
#### INGMAR: This is where the proposal is computed
transformedthetastar = self.modeltheta.proposal(self.transformedthetaparticles, \
self.proposalcovmatrix, hyperparameters = self.modeltheta.hyperparameters,\
proposalmean = self.proposalmean, proposalkernel = self.AP["proposalkernel"])
thetastar = self.modeltheta.untransform(transformedthetastar)
###### INGMAR: This is where the likelihood is estimated
proposedSIRs = ParallelSIRs(self.Nx, thetastar, self.observations[0:(t+1)], self.modelx)
proposedSIRs.first_step()
proposedSIRs.next_steps()
proposedTotalLogLike = proposedSIRs.getTotalLogLike()
acceptations = zeros(self.Ntheta)
proposedpriordensityeval = apply_along_axis(func1d = self.modeltheta.priorlogdensity,\
arr = transformedthetastar, axis = 0)
proposedlogomega = proposedTotalLogLike + proposedpriordensityeval
currentlogomega = self.totalLogLike + self.priordensityeval
# if proposal kernel == "randomwalk", then nothing else needs to be computed
# since the RW is symmetric. If the proposal kernel is independent, then
# the density of the multivariate gaussian used to generate the proposals
# needs to be taken into account
if self.AP["proposalkernel"] == "randomwalk":
pass
elif self.AP["proposalkernel"] == "independent":
invSigma = linalg.inv(self.proposalcovmatrix)
def multinorm_logpdf(x):
centeredx = (x - self.proposalmean)
return -0.5 * dot(dot(centeredx, invSigma), centeredx)
proposaltermstar = apply_along_axis(func1d = multinorm_logpdf, \
arr = transformedthetastar, axis = 0)
proposedlogomega -= proposaltermstar
proposaltermcurr = apply_along_axis(func1d = multinorm_logpdf, \
arr = self.transformedthetaparticles, axis = 0)
currentlogomega -= proposaltermcurr
for i in range(self.Ntheta):
acceptations[i] = (log(random.uniform(size = 1)) < (proposedlogomega[i] - currentlogomega[i]))
if acceptations[i]:
self.transformedthetaparticles[:, i] = transformedthetastar[:, i].copy()
self.thetaparticles[:, i] = thetastar[:, i].copy()
self.totalLogLike[i] = proposedTotalLogLike[i].copy()
self.priordensityeval[i] = proposedpriordensityeval[i].copy()
self.xparticles[:, :, i] = proposedSIRs.xparticles[:, :, i].copy()
acceptrate = sum(acceptations) / self.Ntheta
self.acceptratios.append(acceptrate)
def increaseParticlesNb(self, t):
"""
Double the number of x-particles.
"""
print "increasing Nx: from %i to %i" % (self.Nx, 2 * self.Nx)
self.Nx = 2 * self.Nx
biggerSIRs = ParallelSIRs(self.Nx, self.thetaparticles, self.observations[0:(t+1),:], self.modelx)
biggerSIRs.first_step()
biggerSIRs.next_steps()
biggerTotalLogLike = biggerSIRs.getTotalLogLike()
self.thetalogweights[t, :] = self.thetalogweights[t, :] + biggerTotalLogLike - self.totalLogLike
self.totalLogLike = biggerTotalLogLike.copy()
self.xparticles = biggerSIRs.xparticles.copy()
self.xweights = zeros_like(biggerSIRs.xweights)
self.logxweights = zeros_like(biggerSIRs.xweights)
self.Nxlist.append(self.Nx)
self.increaseindices.append(t)
def increaseParticlesNb(self, t):
"""
Double the number of x-particles.
"""
print "increasing Nx: from %i to %i" % (self.Nx, 2 * self.Nx)
self.Nx = 2 * self.Nx
biggerSIRs = ParallelSIRs(self.Nx, self.thetaparticles, self.observations[0:(t+1),:], self.modelx)
biggerSIRs.first_step()
biggerSIRs.next_steps()
biggerTotalLogLike = biggerSIRs.getTotalLogLike()
self.thetalogweights[t, :] = self.thetalogweights[t, :] + biggerTotalLogLike - self.totalLogLike
self.totalLogLike = biggerTotalLogLike.copy()
self.xparticles = biggerSIRs.xparticles.copy()
self.xweights = zeros_like(biggerSIRs.xweights)
self.logxweights = zeros_like(biggerSIRs.xweights)
self.Nxlist.append(self.Nx)
self.increaseindices.append(t)
