Source code for pymc.stats.log_likelihood

#   Copyright 2023 The PyMC Developers
#   Licensed under the Apache License, Version 2.0 (the "License");
#   you may not use this file except in compliance with the License.
#   You may obtain a copy of the License at
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#   distributed under the License is distributed on an "AS IS" BASIS,
#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#   See the License for the specific language governing permissions and
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from typing import Optional, Sequence, cast

from arviz import InferenceData, dict_to_dataset
from fastprogress import progress_bar

import pymc

from pymc.backends.arviz import _DefaultTrace, coords_and_dims_for_inferencedata
from pymc.model import Model, modelcontext
from pymc.pytensorf import PointFunc
from pymc.util import dataset_to_point_list

__all__ = ("compute_log_likelihood",)

[docs]def compute_log_likelihood( idata: InferenceData, *, var_names: Optional[Sequence[str]] = None, extend_inferencedata: bool = True, model: Optional[Model] = None, sample_dims: Sequence[str] = ("chain", "draw"), progressbar=True, ): """Compute elemwise log_likelihood of model given InferenceData with posterior group Parameters ---------- idata : InferenceData InferenceData with posterior group var_names : sequence of str, optional List of Observed variable names for which to compute log_likelihood. Defaults to all observed variables extend_inferencedata : bool, default True Whether to extend the original InferenceData or return a new one model : Model, optional sample_dims : sequence of str, default ("chain", "draw") progressbar : bool, default True Returns ------- idata : InferenceData InferenceData with log_likelihood group """ posterior = idata["posterior"] model = modelcontext(model) if var_names is None: observed_vars = model.observed_RVs var_names = tuple( for rv in observed_vars) else: observed_vars = [model.named_vars[name] for name in var_names] if not set(observed_vars).issubset(model.observed_RVs): raise ValueError(f"var_names must refer to observed_RVs in the model. Got: {var_names}") # We need to temporarily disable transforms, because the InferenceData only keeps the untransformed values # pylint: disable=used-before-assignment try: original_rvs_to_values = model.rvs_to_values original_rvs_to_transforms = model.rvs_to_transforms model.rvs_to_values = { rv: rv.clone() if rv not in model.observed_RVs else value for rv, value in model.rvs_to_values.items() } model.rvs_to_transforms = {rv: None for rv in model.basic_RVs} elemwise_loglike_fn = model.compile_fn( inputs=model.value_vars, outs=model.logp(vars=observed_vars, sum=False), on_unused_input="ignore", ) elemwise_loglike_fn = cast(PointFunc, elemwise_loglike_fn) finally: model.rvs_to_values = original_rvs_to_values model.rvs_to_transforms = original_rvs_to_transforms # pylint: enable=used-before-assignment # Ignore Deterministics posterior_values = posterior[[ for rv in model.free_RVs]] posterior_pts, stacked_dims = dataset_to_point_list(posterior_values, sample_dims) n_pts = len(posterior_pts) loglike_dict = _DefaultTrace(n_pts) indices = range(n_pts) if progressbar: indices = progress_bar(indices, total=n_pts, display=progressbar) for idx in indices: loglikes_pts = elemwise_loglike_fn(posterior_pts[idx]) for rv_name, rv_loglike in zip(var_names, loglikes_pts): loglike_dict.insert(rv_name, rv_loglike, idx) loglike_trace = loglike_dict.trace_dict for key, array in loglike_trace.items(): loglike_trace[key] = array.reshape( (*[len(coord) for coord in stacked_dims.values()], *array.shape[1:]) ) coords, dims = coords_and_dims_for_inferencedata(model) loglike_dataset = dict_to_dataset( loglike_trace, library=pymc, dims=dims, coords=coords, default_dims=list(sample_dims), skip_event_dims=True, ) if extend_inferencedata: idata.add_groups(dict(log_likelihood=loglike_dataset)) return idata else: return loglike_dataset