def run(
task: Task,
num_samples: int,
num_simulations: int,
batch_size: int = 1,
**kwargs: Any,
) -> torch.Tensor:
"""Runtime baseline
Draws `num_simulations` samples from prior and simulates, discards outcomes,
returns tensor of NaNs.
Args:
task: Task instance
num_samples: Number of samples to generate from posterior
num_simulations: Simulation budget
batch_size: Batch size for simulations
Returns:
Random samples from prior
"""
prior = task.get_prior()
simulator = task.get_simulator()
batch_size = min(batch_size, num_simulations)
num_batches = int(num_simulations / batch_size)
for i in tqdm(range(num_batches)):
_ = simulator(prior(num_samples=batch_size))
assert simulator.num_simulations == num_simulations
samples = float("nan") * torch.ones((num_samples, task.dim_parameters))
return samples
def run_rejection_abc(
task: Task,
num_simulations: int,
population_size: int,
observation: Optional[torch.Tensor] = None,
distance: str = "l2",
batch_size: int = 1000,
):
"""Return posterior and distances from a ABC with fixed budget."""
inferer = MCABC(
simulator=task.get_simulator(max_calls=num_simulations),
prior=task.get_prior_dist(),
simulation_batch_size=batch_size,
distance=distance,
show_progress_bars=True,
)
posterior, distances = inferer(
x_o=observation,
num_simulations=num_simulations,
eps=None,
quantile=population_size / num_simulations,
return_distances=True,
)
return posterior, distances
def run(
task: Task,
num_samples: int,
num_simulations: int,
num_observation: Optional[int] = None,
observation: Optional[torch.Tensor] = None,
num_rounds: int = 10,
neural_net: str = "nsf",
hidden_features: int = 50,
simulation_batch_size: int = 1000,
training_batch_size: int = 10000,
num_atoms: int = 10,
automatic_transforms_enabled: bool = False,
z_score_x: bool = True,
z_score_theta: bool = True,
) -> Tuple[torch.Tensor, int, Optional[torch.Tensor]]:
"""Runs (S)NPE from `sbi`
Args:
task: Task instance
num_samples: Number of samples to generate from posterior
num_simulations: Simulation budget
num_observation: Observation number to load, alternative to `observation`
observation: Observation, alternative to `num_observation`
num_rounds: Number of rounds
neural_net: Neural network to use, one of maf / mdn / made / nsf
hidden_features: Number of hidden features in network
simulation_batch_size: Batch size for simulator
training_batch_size: Batch size for training network
num_atoms: Number of atoms, -1 means same as `training_batch_size`
automatic_transforms_enabled: Whether to enable automatic transforms
z_score_x: Whether to z-score x
z_score_theta: Whether to z-score theta
Returns:
Samples from posterior, number of simulator calls, log probability of true params if computable
"""
assert not (num_observation is None and observation is None)
assert not (num_observation is not None and observation is not None)
log = logging.getLogger(__name__)
if num_rounds == 1:
log.info(f"Running NPE")
num_simulations_per_round = num_simulations
else:
log.info(f"Running SNPE")
num_simulations_per_round = math.floor(num_simulations / num_rounds)
if simulation_batch_size > num_simulations_per_round:
simulation_batch_size = num_simulations_per_round
log.warn("Reduced simulation_batch_size to num_simulation_per_round")
if training_batch_size > num_simulations_per_round:
training_batch_size = num_simulations_per_round
log.warn("Reduced training_batch_size to num_simulation_per_round")
prior = task.get_prior_dist()
if observation is None:
observation = task.get_observation(num_observation)
simulator = task.get_simulator(max_calls=num_simulations)
transforms = task._get_transforms(
automatic_transforms_enabled)["parameters"]
if automatic_transforms_enabled:
prior = wrap_prior_dist(prior, transforms)
simulator = wrap_simulator_fn(simulator, transforms)
density_estimator_fun = posterior_nn(
model=neural_net.lower(),
hidden_features=hidden_features,
z_score_x=z_score_x,
z_score_theta=z_score_theta,
)
inference_method = inference.SNPE_C(
prior, density_estimator=density_estimator_fun)
posteriors = []
proposal = prior
for _ in range(num_rounds):
theta, x = inference.simulate_for_sbi(
simulator,
proposal,
num_simulations=num_simulations_per_round,
simulation_batch_size=simulation_batch_size,
)
density_estimator = inference_method.append_simulations(
theta, x, proposal=proposal).train(
num_atoms=num_atoms,
training_batch_size=training_batch_size,
retrain_from_scratch_each_round=False,
discard_prior_samples=False,
use_combined_loss=False,
show_train_summary=True,
)
posterior = inference_method.build_posterior(density_estimator,
sample_with_mcmc=False)
proposal = posterior.set_default_x(observation)
posteriors.append(posterior)
posterior = wrap_posterior(posteriors[-1], transforms)
assert simulator.num_simulations == num_simulations
samples = posterior.sample((num_samples, )).detach()
if num_observation is not None:
true_parameters = task.get_true_parameters(
num_observation=num_observation)
log_prob_true_parameters = posterior.log_prob(true_parameters)
return samples, simulator.num_simulations, log_prob_true_parameters
else:
return samples, simulator.num_simulations, None
def run(
task: Task,
num_samples: int,
num_simulations: int,
num_observation: Optional[int] = None,
observation: Optional[torch.Tensor] = None,
num_rounds: int = 10,
neural_net: str = "resnet",
hidden_features: int = 50,
simulation_batch_size: int = 1000,
training_batch_size: int = 10000,
num_atoms: int = 10,
automatic_transforms_enabled: bool = True,
mcmc_method: str = "slice_np_vectorized",
mcmc_parameters: Dict[str, Any] = {
"num_chains": 100,
"thin": 10,
"warmup_steps": 100,
"init_strategy": "sir",
"sir_batch_size": 1000,
"sir_num_batches": 100,
},
z_score_x: bool = True,
z_score_theta: bool = True,
variant: str = "B",
) -> Tuple[torch.Tensor, int, Optional[torch.Tensor]]:
"""Runs (S)NRE from `sbi`
Args:
task: Task instance
num_samples: Number of samples to generate from posterior
num_observation: Observation number to load, alternative to `observation`
observation: Observation, alternative to `num_observation`
num_simulations: Simulation budget
num_rounds: Number of rounds
neural_net: Neural network to use, one of linear / mlp / resnet
hidden_features: Number of hidden features in network
simulation_batch_size: Batch size for simulator
training_batch_size: Batch size for training network
num_atoms: Number of atoms, -1 means same as `training_batch_size`
automatic_transforms_enabled: Whether to enable automatic transforms
mcmc_method: MCMC method
mcmc_parameters: MCMC parameters
z_score_x: Whether to z-score x
z_score_theta: Whether to z-score theta
variant: Can be used to switch between SNRE-A (AALR) and -B (SRE)
Returns:
Samples from posterior, number of simulator calls, log probability of true params if computable
"""
assert not (num_observation is None and observation is None)
assert not (num_observation is not None and observation is not None)
log = logging.getLogger(__name__)
if num_rounds == 1:
log.info(f"Running NRE")
num_simulations_per_round = num_simulations
else:
log.info(f"Running SNRE")
num_simulations_per_round = math.floor(num_simulations / num_rounds)
if simulation_batch_size > num_simulations_per_round:
simulation_batch_size = num_simulations_per_round
log.warn("Reduced simulation_batch_size to num_simulation_per_round")
if training_batch_size > num_simulations_per_round:
training_batch_size = num_simulations_per_round
log.warn("Reduced training_batch_size to num_simulation_per_round")
prior = task.get_prior_dist()
if observation is None:
observation = task.get_observation(num_observation)
simulator = task.get_simulator(max_calls=num_simulations)
transforms = task._get_transforms(
automatic_transforms_enabled)["parameters"]
if automatic_transforms_enabled:
prior = wrap_prior_dist(prior, transforms)
simulator = wrap_simulator_fn(simulator, transforms)
classifier = classifier_nn(
model=neural_net.lower(),
hidden_features=hidden_features,
z_score_x=z_score_x,
z_score_theta=z_score_theta,
)
if variant == "A":
inference_class = inference.SNRE_A
inference_method_kwargs = {}
elif variant == "B":
inference_class = inference.SNRE_B
inference_method_kwargs = {"num_atoms": num_atoms}
else:
raise NotImplementedError
inference_method = inference_class(classifier=classifier, prior=prior)
posteriors = []
proposal = prior
mcmc_parameters["warmup_steps"] = 25
for r in range(num_rounds):
theta, x = inference.simulate_for_sbi(
simulator,
proposal,
num_simulations=num_simulations_per_round,
simulation_batch_size=simulation_batch_size,
)
density_estimator = inference_method.append_simulations(
theta, x, from_round=r).train(
training_batch_size=training_batch_size,
retrain_from_scratch_each_round=False,
discard_prior_samples=False,
show_train_summary=True,
**inference_method_kwargs,
)
if r > 1:
mcmc_parameters["init_strategy"] = "latest_sample"
posterior = inference_method.build_posterior(
density_estimator,
mcmc_method=mcmc_method,
mcmc_parameters=mcmc_parameters)
# Copy hyperparameters, e.g., mcmc_init_samples for "latest_sample" strategy.
if r > 0:
posterior.copy_hyperparameters_from(posteriors[-1])
proposal = posterior.set_default_x(observation)
posteriors.append(posterior)
posterior = wrap_posterior(posteriors[-1], transforms)
assert simulator.num_simulations == num_simulations
samples = posterior.sample((num_samples, )).detach()
return samples, simulator.num_simulations, None
def run(
task: Task,
num_samples: int,
num_simulations: int,
num_observation: Optional[int] = None,
observation: Optional[torch.Tensor] = None,
num_chains: int = 10,
num_warmup: int = 1000,
) -> (torch.Tensor, int, Optional[torch.Tensor]):
"""Runs BOLFI from elfi package
Args:
task: Task instance
num_samples: Number of samples to generate from posterior
num_simulations: Simulation budget
num_observation: Observation number to load, alternative to `observation`
observation: Observation, alternative to `num_observation`
num_chains: Number of chains
num_warmup: Warmup steps
Returns:
Samples from posterior, number of simulator calls, log probability of true params if computable
"""
assert not (num_observation is None and observation is None)
assert not (num_observation is not None and observation is not None)
logging.basicConfig(level=logging.INFO)
log = logging.getLogger(__name__)
log.warn("ELFI is not fully supported yet!")
# Initialize model object
m = elfi.ElfiModel()
# Prior
bounds = build_prior(task=task, model=m)
# Observation
if observation is None:
observation = task.get_observation(num_observation)
observation = observation.numpy()
# Simulator
simulator = task.get_simulator(max_calls=num_simulations)
elfi.Simulator(
Simulator(simulator),
*[m[f"parameter_{dim}"] for dim in range(task.dim_parameters)],
observed=observation,
name=task.name,
)
# Euclidean distance
elfi.Distance("euclidean", m[task.name], name="distance")
# Log distance
elfi.Operation(np.log, m["distance"], name="log_distance")
# Inference
num_samples_per_chain = ceil(num_samples / num_chains)
tic = time.time()
bolfi = elfi.BOLFI(model=m, target_name="log_distance", bounds=bounds)
bolfi.fit(n_evidence=num_simulations)
result_BOLFI = bolfi.sample(
num_samples_per_chain + num_warmup,
warmup=num_warmup,
n_chains=num_chains,
info_freq=int(100),
)
toc = time.time()
samples = torch.from_numpy(result_BOLFI.samples_array.astype(
np.float32)).reshape(-1, task.dim_parameters)[:num_samples, :]
assert samples.shape[0] == num_samples
# TODO: return log prob of true parameters
return samples, simulator.num_simulations, None
def run(
task: Task,
num_samples: int,
num_simulations: int,
num_observation: Optional[int] = None,
observation: Optional[torch.Tensor] = None,
num_top_samples: Optional[int] = 100,
quantile: Optional[float] = None,
eps: Optional[float] = None,
distance: str = "l2",
batch_size: int = 1000,
save_distances: bool = False,
kde_bandwidth: Optional[str] = "cv",
sass: bool = False,
sass_fraction: float = 0.5,
sass_feature_expansion_degree: int = 3,
lra: bool = False,
) -> Tuple[torch.Tensor, int, Optional[torch.Tensor]]:
"""Runs REJ-ABC from `sbi`
Choose one of `num_top_samples`, `quantile`, `eps`.
Args:
task: Task instance
num_samples: Number of samples to generate from posterior
num_simulations: Simulation budget
num_observation: Observation number to load, alternative to `observation`
observation: Observation, alternative to `num_observation`
num_top_samples: If given, will use `top=True` with num_top_samples
quantile: Quantile to use
eps: Epsilon threshold to use
distance: Distance to use
batch_size: Batch size for simulator
save_distances: If True, stores distances of samples to disk
kde_bandwidth: If not None, will resample using KDE when necessary, set
e.g. to "cv" for cross-validated bandwidth selection
sass: If True, summary statistics are learned as in
Fearnhead & Prangle 2012.
sass_fraction: Fraction of simulation budget to use for sass.
sass_feature_expansion_degree: Degree of polynomial expansion of the summary
statistics.
lra: If True, posterior samples are adjusted with
linear regression as in Beaumont et al. 2002.
Returns:
Samples from posterior, number of simulator calls, log probability of true params if computable
"""
assert not (num_observation is None and observation is None)
assert not (num_observation is not None and observation is not None)
assert not (num_top_samples is None and quantile is None and eps is None)
log = sbibm.get_logger(__name__)
log.info(f"Running REJ-ABC")
prior = task.get_prior_dist()
simulator = task.get_simulator(max_calls=num_simulations)
kde = kde_bandwidth is not None
if observation is None:
observation = task.get_observation(num_observation)
if num_top_samples is not None and quantile is None:
if sass:
quantile = num_top_samples / (num_simulations -
int(sass_fraction * num_simulations))
else:
quantile = num_top_samples / num_simulations
inference_method = MCABC(
simulator=simulator,
prior=prior,
simulation_batch_size=batch_size,
distance=distance,
show_progress_bars=True,
)
# Returns samples or kde posterior in output.
output, summary = inference_method(
x_o=observation,
num_simulations=num_simulations,
eps=eps,
quantile=quantile,
return_summary=True,
kde=kde,
kde_kwargs={} if run_kde else {"kde_bandwidth": kde_bandwidth},
lra=lra,
sass=sass,
sass_expansion_degree=sass_feature_expansion_degree,
sass_fraction=sass_fraction,
)
assert simulator.num_simulations == num_simulations
if save_distances:
save_tensor_to_csv("distances.csv", summary["distances"])
if kde:
kde_posterior = output
samples = kde_posterior.sample(num_simulations)
# LPTP can only be returned with KDE posterior.
if num_observation is not None:
true_parameters = task.get_true_parameters(
num_observation=num_observation)
log_prob_true_parameters = kde_posterior.log_prob(
true_parameters.squeeze())
return samples, simulator.num_simulations, log_prob_true_parameters
else:
samples = output
return samples, simulator.num_simulations, None
def run(
task: Task,
num_samples: int,
num_simulations: int,
num_observation: Optional[int] = None,
observation: Optional[torch.Tensor] = None,
population_size: Optional[int] = None,
distance: str = "l2",
epsilon_decay: float = 0.2,
distance_based_decay: bool = True,
ess_min: Optional[float] = None,
initial_round_factor: int = 5,
batch_size: int = 1000,
kernel: str = "gaussian",
kernel_variance_scale: float = 0.5,
use_last_pop_samples: bool = True,
algorithm_variant: str = "C",
save_summary: bool = False,
sass: bool = False,
sass_fraction: float = 0.5,
sass_feature_expansion_degree: int = 3,
lra: bool = False,
lra_sample_weights: bool = True,
kde_bandwidth: Optional[str] = "cv",
kde_sample_weights: bool = False,
) -> Tuple[torch.Tensor, int, Optional[torch.Tensor]]:
"""Runs SMC-ABC from `sbi`
SMC-ABC supports two different ways of scheduling epsilon:
1) Exponential decay: eps_t+1 = epsilon_decay * eps_t
2) Distance based decay: the new eps is determined from the "epsilon_decay"
quantile of the distances of the accepted simulations in the previous population. This is used if `distance_based_decay` is set to True.
Args:
task: Task instance
num_samples: Number of samples to generate from posterior
num_simulations: Simulation budget
num_observation: Observation number to load, alternative to `observation`
observation: Observation, alternative to `num_observation`
population_size: If None, uses heuristic: 1000 if `num_simulations` is greater
than 10k, else 100
distance: Distance function, options = {l1, l2, mse}
epsilon_decay: Decay for epsilon; treated as quantile in case of distance based decay.
distance_based_decay: Whether to determine new epsilon from quantile of
distances of the previous population.
ess_min: Threshold for resampling a population if effective sampling size is
too small.
initial_round_factor: Used to determine initial round size
batch_size: Batch size for the simulator
kernel: Kernel distribution used to perturb the particles.
kernel_variance_scale: Scaling factor for kernel variance.
use_last_pop_samples: If True, samples of a population that was quit due to
budget are used by filling up missing particles from the previous
population.
algorithm_variant: There are three SMCABC variants implemented: A, B, and C.
See doctstrings in SBI package for more details.
save_summary: Whether to save a summary containing all populations, distances,
etc. to file.
sass: If True, summary statistics are learned as in
Fearnhead & Prangle 2012.
sass_fraction: Fraction of simulation budget to use for sass.
sass_feature_expansion_degree: Degree of polynomial expansion of the summary
statistics.
lra: If True, posterior samples are adjusted with
linear regression as in Beaumont et al. 2002.
lra_sample_weights: Whether to weigh LRA samples
kde_bandwidth: If not None, will resample using KDE when necessary, set
e.g. to "cv" for cross-validated bandwidth selection
kde_sample_weights: Whether to weigh KDE samples
Returns:
Samples from posterior, number of simulator calls, log probability of true params if computable
"""
assert not (num_observation is None and observation is None)
assert not (num_observation is not None and observation is not None)
log = sbibm.get_logger(__name__)
smc_papers = dict(A="Toni 2010", B="Sisson et al. 2007", C="Beaumont et al. 2009")
log.info(f"Running SMC-ABC as in {smc_papers[algorithm_variant]}.")
prior = task.get_prior_dist()
simulator = task.get_simulator(max_calls=num_simulations)
if observation is None:
observation = task.get_observation(num_observation)
if population_size is None:
population_size = 100
if num_simulations > 10_000:
population_size = 1000
population_size = min(population_size, num_simulations)
initial_round_size = clip_int(
value=initial_round_factor * population_size,
minimum=population_size,
maximum=max(0.5 * num_simulations, population_size),
)
inference_method = SMCABC(
simulator=simulator,
prior=prior,
simulation_batch_size=batch_size,
distance=distance,
show_progress_bars=True,
kernel=kernel,
algorithm_variant=algorithm_variant,
)
posterior, summary = inference_method(
x_o=observation,
num_particles=population_size,
num_initial_pop=initial_round_size,
num_simulations=num_simulations,
epsilon_decay=epsilon_decay,
distance_based_decay=distance_based_decay,
ess_min=ess_min,
kernel_variance_scale=kernel_variance_scale,
use_last_pop_samples=use_last_pop_samples,
return_summary=True,
lra=lra,
lra_with_weights=lra_sample_weights,
sass=sass,
sass_fraction=sass_fraction,
sass_expansion_degree=sass_feature_expansion_degree,
)
if save_summary:
log.info("Saving smcabc summary to csv.")
pd.DataFrame.from_dict(summary,).to_csv("summary.csv", index=False)
assert simulator.num_simulations == num_simulations
if kde_bandwidth is not None:
samples = posterior._samples
log.info(
f"KDE on {samples.shape[0]} samples with bandwidth option {kde_bandwidth}"
)
kde = get_kde(
samples,
bandwidth=kde_bandwidth,
sample_weight=posterior._log_weights.exp() if kde_sample_weights else None,
)
samples = kde.sample(num_samples)
else:
samples = posterior.sample((num_samples,)).detach()
if num_observation is not None:
true_parameters = task.get_true_parameters(num_observation=num_observation)
log_prob_true_parameters = posterior.log_prob(true_parameters)
return samples, simulator.num_simulations, log_prob_true_parameters
else:
return samples, simulator.num_simulations, None
def run(
task: Task,
num_samples: int,
num_simulations: int,
num_observation: Optional[int] = None,
observation: Optional[torch.Tensor] = None,
population_size: Optional[int] = None,
distance: Optional[str] = "l2",
initial_round_factor: int = 5,
batch_size: int = 1000,
epsilon_decay: Optional[float] = 0.5,
kernel: Optional[str] = "gaussian",
kernel_variance_scale: Optional[float] = 0.5,
population_strategy: Optional[str] = "constant",
use_last_pop_samples: bool = False,
num_workers: int = 1,
sass: bool = False,
sass_sample_weights: bool = False,
sass_feature_expansion_degree: int = 1,
sass_fraction: float = 0.5,
lra: bool = False,
lra_sample_weights: bool = True,
kde_bandwidth: Optional[str] = None,
kde_sample_weights: bool = False,
) -> Tuple[torch.Tensor, int, Optional[torch.Tensor]]:
"""ABC-SMC using pyabc toolbox
Args:
task: Task instance
num_samples: Number of samples to generate from posterior
num_simulations: Simulation budget
num_observation: Observation number to load, alternative to `observation`
observation: Observation, alternative to `num_observation`
population_size: If None, uses heuristic: 1000 if `num_simulations` is greater
than 10k, else 100
distance: Distance function, options = {l1, l2, mse}
epsilon_decay: Decay for epsilon, quantile based.
kernel: Kernel distribution used to perturb the particles.
kernel_variance_scale: Scaling factor for kernel variance.
sass: If True, summary statistics are learned as in
Fearnhead & Prangle 2012.
sass_sample_weights: Whether to weigh SASS samples
sass_feature_expansion_degree: Degree of polynomial expansion of the summary
statistics.
sass_fraction: Fraction of simulation budget to use for sass.
lra: If True, posterior samples are adjusted with
linear regression as in Beaumont et al. 2002.
lra_sample_weights: Whether to weigh LRA samples
kde_bandwidth: If not None, will resample using KDE when necessary, set
e.g. to "cv" for cross-validated bandwidth selection
kde_sample_weights: Whether to weigh KDE samples
Returns:
Samples from posterior, number of simulator calls, log probability of true params if computable
"""
assert not (num_observation is None and observation is None)
assert not (num_observation is not None and observation is not None)
log = sbibm.get_logger(__name__)
db = "sqlite:///" + os.path.join(
tempfile.gettempdir(),
f"pyabc_{time.time()}_{random.randint(0, 1e9)}.db")
# Wrap sbibm prior and simulator for pyABC
prior = wrap_prior(task)
simulator = PyAbcSimulator(task)
distance_str = distance
if observation is None:
observation = task.get_observation(num_observation)
# Population size strategy
if population_size is None:
population_size = 100
if num_simulations > 10_000:
population_size = 1000
# Find initial epsilon with rej abc run.
initial_round_size = clip_int(
value=initial_round_factor * population_size,
minimum=population_size,
maximum=max(0.5 * num_simulations, population_size),
)
log.info(
f"Running REJ-ABC with {initial_round_size} samples to find initial epsilon."
)
_, distances = run_rejection_abc(task, initial_round_size, population_size,
observation, distance_str, batch_size)
initial_epsilon = distances[-1].item()
# Wrap observation and distance for pyabc.
distance = get_distance(distance_str)
observation = np.atleast_1d(np.array(observation, dtype=float).squeeze())
# Define quantile based epsilon decay.
epsilon = pyabc.epsilon.QuantileEpsilon(initial_epsilon=initial_epsilon,
alpha=epsilon_decay)
# Perturbation kernel
transition = pyabc.transition.MultivariateNormalTransition(
scaling=kernel_variance_scale)
population_size = min(population_size, num_simulations)
if population_strategy == "constant":
population_size_strategy = population_size
elif population_strategy == "adaptive":
raise NotImplementedError("Not implemented atm.")
population_size_strategy = pyabc.populationstrategy.AdaptivePopulationSize(
start_nr_particles=population_size,
max_population_size=int(10 * population_size),
min_population_size=int(0.1 * population_size),
)
# Multiprocessing
if num_workers > 1:
sampler = pyabc.sampler.MulticoreParticleParallelSampler(
n_procs=num_workers)
else:
sampler = pyabc.sampler.SingleCoreSampler(check_max_eval=False)
# Collect kwargs
kwargs = dict(
parameter_priors=[prior],
distance_function=distance,
population_size=population_size_strategy,
transitions=[transition],
eps=epsilon,
sampler=sampler,
)
# Semi-automatic summary statistics.
if sass:
num_pilot_simulations = int(sass_fraction * num_simulations)
log.info(f"SASS pilot run with {num_pilot_simulations} simulations.")
kwargs["models"] = [simulator]
# Run pyabc with fixed budget.
pilot_theta, pilot_weights = run_pyabc(
task,
db,
num_pilot_simulations,
observation,
pyabc_kwargs=kwargs,
use_last_pop_samples=use_last_pop_samples,
distance_str=distance_str,
batch_size=batch_size,
)
# Regression
# TODO: Posterior does not return xs, which we would need for
# regression adjustment. So we will resimulate, which is
# unneccessary. Should ideally change `inference_method` to return xs
# if requested instead. This step thus does not count towards budget
pilot_x = task.get_simulator(max_calls=None)(pilot_theta)
# Run SASS.
sumstats_transform = get_sass_transform(
theta=pilot_theta,
x=pilot_x,
expansion_degree=sass_feature_expansion_degree,
sample_weight=pilot_weights if sass_sample_weights else None,
)
# Update simulator to use sass summary stats.
def sumstats_simulator(theta):
# Pyabc simulator returns dict.
x = simulator(theta)["data"].reshape(1, -1)
# Transform return Tensor.
sx = sumstats_transform(x)
return dict(data=sx.numpy().squeeze())
observation = sumstats_transform(observation.reshape(1, -1))
observation = np.atleast_1d(
np.array(observation, dtype=float).squeeze())
log.info(f"Finished learning summary statistics.")
else:
sumstats_simulator = simulator
num_pilot_simulations = 0
population_size = min(population_size, num_simulations)
log.info("""Running ABC-SMC-pyabc with {} simulations""".format(
num_simulations - num_pilot_simulations))
kwargs["models"] = [sumstats_simulator]
# Run pyabc with fixed budget.
particles, weights = run_pyabc(
task,
db,
num_simulations=num_simulations - num_pilot_simulations,
observation=observation,
pyabc_kwargs=kwargs,
use_last_pop_samples=use_last_pop_samples,
distance_str=distance_str,
batch_size=batch_size,
)
if lra:
log.info(f"Running linear regression adjustment.")
# TODO: Posterior does not return xs, which we would need for
# regression adjustment. So we will resimulate, which is
# unneccessary. Should ideally change `inference_method` to return xs
# if requested instead.
xs = task.get_simulator(max_calls=None)(particles)
# NOTE: If posterior is bounded we should do the regression in
# unbounded space, as described in https://arxiv.org/abs/1707.01254
transform_to_unbounded = True
transforms = task._get_transforms(transform_to_unbounded)["parameters"]
# Update the particles with LRA.
particles = run_lra(
theta=particles,
x=xs,
observation=torch.tensor(observation,
dtype=torch.float32).unsqueeze(0),
sample_weight=weights if lra_sample_weights else None,
transforms=transforms,
)
# TODO: Maybe set weights uniform because they can't be updated?
# weights = torch.ones(particles.shape[0]) / particles.shape[0]
if kde_bandwidth is not None:
samples = particles
log.info(
f"KDE on {samples.shape[0]} samples with bandwidth option {kde_bandwidth}"
)
kde = get_kde(
samples,
bandwidth=kde_bandwidth,
sample_weight=weights if kde_sample_weights else None,
)
samples = kde.sample(num_samples)
else:
log.info(f"Sampling {num_samples} samples from trace")
samples = sample_with_weights(particles,
weights,
num_samples=num_samples)
log.info(f"Unique samples: {torch.unique(samples, dim=0).shape[0]}")
return samples, simulator.simulator.num_simulations, None
def run(
task: Task,
num_samples: int,
num_simulations: int,
num_simulations_per_step: int = 100,
num_observation: Optional[int] = None,
observation: Optional[torch.Tensor] = None,
automatic_transforms_enabled: bool = False,
mcmc_method: str = "slice_np",
mcmc_parameters: Dict[str, Any] = {},
diag_eps: float = 0.0,
) -> (torch.Tensor, int, Optional[torch.Tensor]):
"""Runs (S)NLE from `sbi`
Args:
task: Task instance
num_observation: Observation number to load, alternative to `observation`
observation: Observation, alternative to `num_observation`
num_samples: Number of samples to generate from posterior
num_simulations: Simulation budget
num_simulations_per_step: Number of simulations per MCMC step
automatic_transforms_enabled: Whether to enable automatic transforms
mcmc_method: MCMC method
mcmc_parameters: MCMC parameters
diag_eps: Epsilon applied to diagonal
Returns:
Samples from posterior, number of simulator calls, log probability of true params if computable
"""
assert not (num_observation is None and observation is None)
assert not (num_observation is not None and observation is not None)
log = logging.getLogger(__name__)
log.info(f"Running SL")
prior = task.get_prior_dist()
if observation is None:
observation = task.get_observation(num_observation)
simulator = task.get_simulator()
transforms = task._get_transforms(automatic_transforms_enabled)["parameters"]
prior = wrap_prior_dist(prior, transforms)
simulator = wrap_simulator_fn(simulator, transforms)
likelihood_estimator = SynthLikNet(
simulator=simulator,
num_simulations_per_step=num_simulations_per_step,
diag_eps=diag_eps,
)
posterior = LikelihoodBasedPosterior(
method_family="snle",
neural_net=likelihood_estimator,
prior=prior,
x_shape=observation.shape,
mcmc_parameters=mcmc_parameters,
)
posterior.set_default_x(observation)
posterior = wrap_posterior(posterior, transforms)
# assert simulator.num_simulations == num_simulations
samples = posterior.sample((num_samples,)).detach()
return samples, simulator.num_simulations, None