def lstsq_laplace_factor_approx(
model_approx: EPMeanField,
factor: Factor,
delta: float = 0.5,
opt_kws: Optional[Dict[str, Any]] = None):
"""
"""
factor_approx = model_approx.factor_approximation(factor)
opt = LeastSquaresOpt(
factor_approx, **({} if opt_kws is None else opt_kws))
mode, covar, result = opt.least_squares()
message = (
"optimise.lsq_sq_laplace_factor_approx: "
f"nfev={result.nfev}, njev={result.njev}, "
f"optimality={result.optimality}, "
f"cost={result.cost}, "
f"status={result.status}, message={result.message}",)
status = Status(result.success, message)
model_dist = MeanField({
v: factor_approx.factor_dist[v].from_mode(
mode[v],
covar.get(v))
for v in mode
})
projection, status = factor_approx.project(
model_dist, delta=delta, status=status)
return model_approx.project(projection, status=status)
def factor_approximation(self, factor: Factor) -> FactorApproximation:
"""
Create an approximation for one factor.
This comprises:
- The factor
- The factor's variable distributions
- The cavity distribution, which is the product of the distributions
for each variable for all other factors
- The model distribution, which is the product of the distributions
for each variable for all factors
Parameters
----------
factor
Some factor
Returns
-------
An object comprising distributions with a specific distribution excluding
that factor
"""
factor_mean_field = self._factor_mean_field.copy()
factor_dist = factor_mean_field.pop(factor)
cavity_dist = MeanField({v: 1.0
for v in factor_dist.all_variables
}).prod(*factor_mean_field.values())
model_dist = factor_dist.prod(cavity_dist)
return FactorApproximation(factor, cavity_dist, factor_dist,
model_dist)
def project_factor_approx_sample(
factor_approx: FactorApproximation,
sample: SamplingResult) -> Dict[str, AbstractMessage]:
# Calculate log_norm
log_weights = sample.log_weights
# Need to collapse the weights to match the shapes of the different
# variables
variable_log_weights = {
v: factor_approx.factor.collapse(v, log_weights, agg_func=np.sum)
for v in factor_approx.cavity_dist
}
log_weights = log_weights.sum(tuple(range(1, log_weights.ndim)))
# subtract max log_weight for numerical stability
log_w_max = np.max(log_weights)
w = np.exp(log_weights - log_w_max)
log_norm = np.log(w.mean(0)) + log_w_max
model_dist = MeanField(
{
v: factor_approx.factor_dist[v].project(
x, variable_log_weights.get(v))
for v, x in chain(sample.samples.items(),
sample.det_variables.items())
},
log_norm=log_norm)
return model_dist
def calc_exact_update(self, mean_field) -> "MeanField":
if self._calc_exact_update:
from autofit.graphical.mean_field import MeanField
projection = self._calc_exact_update(
*self.resolve_args_and_out(mean_field))
return MeanField(
nested_filter(is_variable, self.args + (self.factor_out, ),
projection))
else:
raise NotImplementedError
def factor_approximation(self, factor: Factor) -> FactorApproximation:
factor_mean_field = self._factor_mean_field.copy()
factor_dist = factor_mean_field.pop(factor)
cavity_dist = MeanField.prod(
{v: 1.
for v in factor_dist.all_variables},
*(dist for fac, dist in factor_mean_field.items()))
# cavity_dist.log_norm = 0.
model_dist = factor_dist.prod(cavity_dist)
return FactorApproximation(factor, cavity_dist, factor_dist,
model_dist)
def refine_approx(
self,
factor_approx: FactorApprox,
mean_field: MeanField = None,
params: VariableData = None,
n_refine=None,
) -> Tuple[MeanField, Status]:
mean_field = mean_field or factor_approx.model_dist
state = self.prepare_state(factor_approx, mean_field, params)
next_state = self.refine_state(state,
mean_field.sample,
n_refine=n_refine)
return mean_field.from_opt_state(next_state)
def from_approx_dists(
cls,
factor_graph: FactorGraph,
approx_dists: Dict[Variable, AbstractMessage],
) -> "EPMeanField":
factor_mean_field = {
factor: MeanField(
{v: approx_dists[v].copy()
for v in factor.all_variables})
for factor in factor_graph.factors
}
return cls(factor_graph, factor_mean_field)
def optimise_approx(self,
factor_approx: FactorApprox,
mean_field: MeanField = None,
params: VariableData = None,
**kwargs) -> Tuple[MeanField, Status]:
mean_field = mean_field or factor_approx.model_dist
state = self.prepare_state(factor_approx, mean_field, params)
next_state, status = self.optimise_state(state, **kwargs)
# if status.flag != StatusFlag.SUCCESS:
next_state = max(state, next_state, key=lambda x: x.value)
next_state = self.refine_state(next_state,
mean_field.sample,
n_refine=kwargs.get("n_refine"))
projection = mean_field.from_opt_state(next_state)
return projection, status
def project_mean_field(
self,
new_dist: MeanField,
factor_approx: FactorApproximation,
delta: float = 1.0,
status: Status = Status(),
) -> Tuple["EPMeanField", Status]:
new_factor_dist, status = new_dist.update_factor_mean_field(
factor_approx.cavity_dist,
factor_approx.factor_dist,
delta=delta,
status=status,
)
factor_mean_field = self.factor_mean_field
factor_mean_field[factor_approx.factor] = new_factor_dist
new_approx = type(self)(
factor_graph=self._factor_graph,
factor_mean_field=factor_mean_field,
)
return new_approx, status
def project_mean_field(
self,
new_dist: MeanField,
factor_approx: FactorApproximation,
delta: float = 1.0,
status: Status = Status(),
) -> Tuple["EPMeanField", Status]:
factor_mean_field = self.factor_mean_field
# We're fitting the full factor_dist, not the subset factor_dist
rescale1 = {
v: 1 - scale
for v, scale in self._factor_rescale[factor_approx.factor].items()
}
last_factor_dist = factor_mean_field.pop(factor_approx.factor)
subset_cavity_dist = last_factor_dist.rescale(rescale1)
new_factor_dist, status = new_dist.update_factor_mean_field(
factor_approx.cavity_dist,
factor_approx.factor_dist,
delta=delta,
status=status,
)
factor_mean_field[
factor_approx.factor] = new_factor_dist * subset_cavity_dist
new_approx = type(self)(
factor_graph=self._factor_graph,
factor_mean_field=factor_mean_field,
factor_rescale=self._factor_rescale,
factor_subset_factor=self._factor_subset_factor,
ep_mean_field=self._ep_mean_field,
plates_index=self._plates_index,
)
return new_approx, status
def make_posdef_hessian(mean_field, variables):
return MeanField.precision(mean_field, variables)
def mean_field(self) -> MeanField:
return MeanField({v: 1.0
for v in self.all_variables
}).prod(*self._factor_mean_field.values())
