mojolearn.ExtraTreesClassifier#

class mojolearn.ExtraTreesClassifier(n_estimators=100, *, criterion='gini', max_depth=None, min_samples_split=2, min_samples_leaf=1, min_weight_fraction_leaf=0.0, max_features='sqrt', max_leaf_nodes=None, min_impurity_decrease=0.0, bootstrap=False, oob_score=False, n_jobs=None, random_state=None, verbose=0, warm_start=False, class_weight=None, ccp_alpha=0.0, max_samples=None, monotonic_cst=None, device='gpu', inference_engine='auto', numeric_mode=None)#

Extra-trees classifier with scikit-learn’s defaults.

Extremely randomized trees: each split draws one random threshold per candidate feature (scikit-learn’s random splitter, Geurts, Ernst and Wehenkel 2006) instead of searching for the best one. Defaults are scikit-learn’s, name for name. Every scikit-learn parameter is either honoured or refused by name; none is accepted and ignored.

X is converted to float32; NaN or infinity in X raises ValueError. y may hold numbers or strings; NaN labels are refused. Supports the fast (Apple GPUs only) and identical numeric modes through numeric_mode.

Parameters:

n_estimators (int, default 100) – Number of trees.
criterion ({‘gini’, ‘entropy’, ‘log_loss’}, default ‘gini’) – Split criterion; ‘log_loss’ is an alias of ‘entropy’. Other names raise NotImplementedError.
max_depth (int or None, default None) – Maximum tree depth; None means unlimited.
min_samples_split (int, default 2) – Minimum rows needed to split a node.
min_samples_leaf (int, default 1) – Minimum rows in a leaf.
min_weight_fraction_leaf (float, default 0.0) – Only 0.0 is accepted; sample weights are not supported.
max_features ({‘sqrt’, ‘log2’}, int, float or None, default ‘sqrt’) – Features drawn per split: a name, a count, a fraction, or None for all features.
max_leaf_nodes (int or None, default None) – scikit-learn’s best-first growth: an int grows each tree to exactly that many leaves, expanding the node with the largest impurity improvement first (ties go to the smaller node id). None keeps depth-wise growth. The improvement is computed in float32.
min_impurity_decrease (float, default 0.0) – Minimum impurity decrease required to split.
bootstrap (bool, default False) – Sample rows with replacement for each tree.
oob_score (bool, default False) – Only False is accepted; out-of-bag scoring is not implemented.
n_jobs (None, default None) – Only None is accepted; any other value raises NotImplementedError.
random_state (int or None, default None) – Seed. None means seed 0, so the default fit is deterministic, unlike scikit-learn.
verbose (int, default 0) – Only 0 is accepted; any other value raises NotImplementedError.
warm_start (bool, default False) – Only False is accepted; there is no incremental fit.
class_weight (None, default None) – Only None is accepted; any other value raises NotImplementedError in fit.
ccp_alpha (float, default 0.0) – Only 0.0 is accepted; cost-complexity pruning is not implemented.
max_samples (int, float or None, default None) – Rows drawn per tree when bootstrap=True, resolved as in scikit-learn: None means all rows, an int is a count, a float f means max(int(f * n_samples), 1). Setting it without bootstrap raises an error, as in scikit-learn.
monotonic_cst (None, default None) – Only None is accepted.
device ({‘gpu’}, default ‘gpu’) – Only ‘gpu’ is accepted; other values raise ValueError. On a CPU-only install the same calls run the host build of the trainer.
inference_engine ({‘auto’, ‘sequential’, ‘parallel_groves’}, default ‘auto’) – How predict reduces over trees. ‘auto’ uses ‘parallel_groves’ in fast mode and ‘sequential’ otherwise.
numeric_mode ({‘fast’, ‘identical’} or None, default None) – Numeric mode for this estimator; None uses the package default. 'fast' is available on Apple GPUs only.

Variables:

classes_ (list) – Class labels in sorted order (numbers by value, strings by code point).
n_features_in_ (int) – Number of features seen in fit.

Examples

>>> import numpy as np, mojolearn
>>> rng = np.random.default_rng(0)
>>> X = rng.random((1000, 8), dtype=np.float32)
>>> y = (X[:, 0] > 0.5).astype(np.int64)
>>> model = mojolearn.ExtraTreesClassifier(n_estimators=50).fit(X, y)
>>> proba = model.predict_proba(X)

User guide: Trees and gradient boosting

Choosing an estimator

Methods

`apply`(X)	Return tree-relative leaf IDs, shape (rows, trees), from the native walk.
`fit`(X, y)	Fit the forest.
`get_params`([deep])
`load`(path)	Load a forest saved by `save`.
`numeric_mode_used`()	The numeric mode this estimator runs in.
`predict`(X)	Predicted class labels: the argmax of `predict_proba`, first maximum winning, mapped through `classes_`.
`predict_proba`(X)	Class probabilities: the average of the trees' leaf class distributions.
`predict_with_leaves`(X)	Return ordered raw mean scores (rows, outputs) and leaf IDs (rows, trees).
`save`(path)	Write the fitted forest to `path` as an npz file.
`score`(X, y[, sample_weight])	Mode-aware GPU accuracy or Float32 R², weighted when `sample_weight` is given (scikit-learn's weighted accuracy and R² on the pinned-sum path of `metrics.accuracy_score` and `metrics.r2_score`).
`set_params`(**params)	Set constructor parameters.
`staged_predict`(X)	Return eager mean prefixes, shape (rows, trees, outputs), in tree order.
`vendor_used`()	The GPU backend this estimator runs on.

fit(X, y)#

Fit the forest.

Parameters:

X (array-like of shape (n_samples, n_features)) – Training data, converted to float32.
y (array-like of shape (n_samples,)) – Targets.

Returns:

self

predict_proba(X)#

Class probabilities: the average of the trees’ leaf class distributions.

Returns:: Array of shape (n_samples, n_classes), float64 – Columns in classes_ order.

predict(X)#

Predicted class labels: the argmax of predict_proba, first maximum winning, mapped through classes_.

Returns:: Array or list of shape (n_samples,) – An int64 or float64 Array for numeric labels, a Python list for string labels.

apply(X)#: Return tree-relative leaf IDs, shape (rows, trees), from the native walk.

classmethod load(path)#

Load a forest saved by save.

The loaded model predicts; it does not refit. Loading a file saved by a different estimator class raises ValueError.

numeric_mode_used()#

The numeric mode this estimator runs in.

Returns:: str – 'identical' or 'fast', read from the compiled binary the estimator uses, not from the argument it was given.

predict_with_leaves(X)#

Return ordered raw mean scores (rows, outputs) and leaf IDs (rows, trees).

Classifier scores are undecoded class votes. This auxiliary ordered contract is independent of an explicitly selected groves engine.

save(path)#

Write the fitted forest to path as an npz file.

The file holds the prediction arrays exactly as fitted, with exact dtypes; floats never pass through decimal text. A model saved with the ‘parallel_groves’ inference engine also records its engine and numeric mode. The file bytes depend only on the model, so equal models give equal file hashes on any machine.

score(X, y, sample_weight=None)#

Mode-aware GPU accuracy or Float32 R², weighted when sample_weight is given (scikit-learn’s weighted accuracy and R² on the pinned-sum path of metrics.accuracy_score and metrics.r2_score).

Class labels are compared without narrowing their values by the x_metrics binding’s grouped match count (accuracy_fraction). Regression scoring uses the same Float32 target domain as tree fitting.

set_params(**params)#: Set constructor parameters. The estimator is rebuilt through its constructor, so every constructor check runs again and any fitted state is dropped, as a new setting invalidates it.

staged_predict(X)#

Return eager mean prefixes, shape (rows, trees, outputs), in tree order.

Each prefix uses the fixed increasing-tree fold through that tree. Only this requested API allocates the complete prefix buffer.

vendor_used()#

The GPU backend this estimator runs on.

Returns:: str – 'metal', 'cuda' or 'hip', read from the compiled binary the estimator uses.