Unreleased

# Unreleased

drift¶

The river.drift sub-package is now clean under strict mypy, and the river.drift.* entry was removed from the non-strict overrides in pyproject.toml. Public signatures and docstrings are unchanged.
Fixed a latent bug in drift.datasets.base.Dataset._annotations_aggregated, which read a nonexistent self._annotations attribute and keyed the intersection branch on the integer 0 instead of the annotator key. The method has no callers today, so behavior is unchanged.
DriftRetrainingClassifier now passes a bool instead of an int as the error indicator to its wrapped binary drift detector.

Added CategoricalNB, a Naive Bayes classifier for categorical features that maintains per-class frequencies for every value of every feature, with additive (Laplace) smoothing and support for both online and mini-batch modes.

BayesianLinearRegression.predict_dist_one now replaces BayesianLinearRegression.predict_one(..., with_dist=True) to better respect the Regressor interface while still being able to predict distributions.

MultinomialNB.learn_many, predict_many, and predict_proba_many now accept any narwhals-supported eager backend (pandas, polars, pyarrow, ...) instead of being pandas-only, preserving the input backend (including the pandas index) on output. A backend-agnostic BaseNB.predict_many was added so the argmax-over-probabilities logic is shared by all Naive Bayes variants.

stream.Cache now writes a pass to a temporary file and renames it into place once the stream is exhausted. An interrupted first pass (a break, an exception, an abandoned generator) used to leave a truncated file behind, which every later pass then read back as if it were the whole dataset.
stream.iter_csv no longer yields an empty x for a blank line in the middle of a file. csv.DictReader skips those, and stream.iter_arff already did.
stream.iter_csv now closes the file it opened and restores csv.field_size_limit even when the stream is not exhausted, e.g. when the caller breaks out of the loop. Only the file iter_csv opened itself is closed; a buffer passed in by the caller is still left open.
stream.iter_sql now closes the result it iterates, so the underlying cursor is released once the stream is exhausted or abandoned.
stream.cache, stream.iter_csv, and stream.iter_sql are now clean under strict mypy. sqlalchemy is type-checked rather than ignored, so the query and conn arguments of stream.iter_sql are checked against the SQLAlchemy 2.0 types.

preprocessing.Normalizer now handles zero vectors without raising a ZeroDivisionError. A zero vector is returned unchanged instead.

Fixed the radius of cluster.DenStream micro-clusters, which used the norm of the vector of squared sums instead of the sum of its components and was 0 away from the origin. The docstring example now uses epsilon=1.0.
cluster.DenStream.predict_one now expands a cluster past the direct neighbors of its first micro-cluster. The neighbors of a neighbor were only queued if they already had a label, so a chain of micro-clusters came out as several clusters.
New cluster.DenStream micro-clusters no longer reuse the key of a deleted one, which overwrote an existing micro-cluster.