from sklearn.utils._param_validation import StrOptions

from sktree._lib.sklearn.ensemble._forest import ForestClassifier, ForestRegressor
from sktree.tree import (
    ObliqueDecisionTreeClassifier,
    ObliqueDecisionTreeRegressor,
    PatchObliqueDecisionTreeClassifier,
    PatchObliqueDecisionTreeRegressor,
)

from ..tree._neighbors import SimMatrixMixin


class ObliqueRandomForestClassifier(SimMatrixMixin, ForestClassifier):
    """
    An oblique random forest classifier.

    A oblique random forest is a meta estimator similar to a random
    forest that fits a number of oblique decision tree classifiers
    on various sub-samples of the dataset and uses averaging to
    improve the predictive accuracy and control over-fitting.

    The sub-sample size is controlled with the `max_samples` parameter if
    `bootstrap=True` (default), otherwise the whole dataset is used to build
    each tree.

    Read more in the :ref:`User Guide <sklearn:forest>`.

    Parameters
    ----------
    n_estimators : int, default=100
        The number of trees in the forest.

    criterion : {"gini", "entropy"}, default="gini"
        The function to measure the quality of a split. Supported criteria are
        "gini" for the Gini impurity and "entropy" for the information gain.
        Note: this parameter is tree-specific.

    max_depth : int, default=None
        The maximum depth of the tree. If None, then nodes are expanded until
        all leaves are pure or until all leaves contain less than
        min_samples_split samples.

    min_samples_split : int or float, default=2
        The minimum number of samples required to split an internal node:

        - If int, then consider `min_samples_split` as the minimum number.
        - If float, then `min_samples_split` is a fraction and
          `ceil(min_samples_split * n_samples)` are the minimum
          number of samples for each split.

    min_samples_leaf : int or float, default=1
        The minimum number of samples required to be at a leaf node.
        A split point at any depth will only be considered if it leaves at
        least ``min_samples_leaf`` training samples in each of the left and
        right branches.  This may have the effect of smoothing the model,
        especially in regression.

        - If int, then consider `min_samples_leaf` as the minimum number.
        - If float, then `min_samples_leaf` is a fraction and
          `ceil(min_samples_leaf * n_samples)` are the minimum
          number of samples for each node.

    min_weight_fraction_leaf : float, default=0.0
        The minimum weighted fraction of the sum total of weights (of all
        the input samples) required to be at a leaf node. Samples have
        equal weight when sample_weight is not provided.

    max_features : {"sqrt", "log2", None}, int or float, default="sqrt"
        The number of features to consider when looking for the best split:

        - If int, then consider `max_features` features at each split.
        - If float, then `max_features` is a fraction and
          `round(max_features * n_features)` features are considered at each
          split.
        - If "auto", then `max_features=sqrt(n_features)`.
        - If "sqrt", then `max_features=sqrt(n_features)`.
        - If "log2", then `max_features=log2(n_features)`.
        - If None, then `max_features=n_features`.

        Note: the search for a split does not stop until at least one
        valid partition of the node samples is found, even if it requires to
        effectively inspect more than ``max_features`` features.

    max_leaf_nodes : int, default=None
        Grow trees with ``max_leaf_nodes`` in best-first fashion.
        Best nodes are defined as relative reduction in impurity.
        If None then unlimited number of leaf nodes.

    min_impurity_decrease : float, default=0.0
        A node will be split if this split induces a decrease of the impurity
        greater than or equal to this value.

        The weighted impurity decrease equation is the following::

            N_t / N * (impurity - N_t_R / N_t * right_impurity
                                - N_t_L / N_t * left_impurity)

        where ``N`` is the total number of samples, ``N_t`` is the number of
        samples at the current node, ``N_t_L`` is the number of samples in the
        left child, and ``N_t_R`` is the number of samples in the right child.

        ``N``, ``N_t``, ``N_t_R`` and ``N_t_L`` all refer to the weighted sum,
        if ``sample_weight`` is passed.

    bootstrap : bool, default=True
        Whether bootstrap samples are used when building trees. If False, the
        whole dataset is used to build each tree.

    oob_score : bool, default=False
        Whether to use out-of-bag samples to estimate the generalization score.
        Only available if bootstrap=True.

    n_jobs : int, default=None
        The number of jobs to run in parallel. :meth:`fit`, :meth:`predict`,
        :meth:`decision_path` and :meth:`apply` are all parallelized over the
        trees. ``None`` means 1 unless in a `joblib.parallel_backend`
        context. ``-1`` means using all processors. See :term:`Glossary
        <n_jobs>` for more details.

    random_state : int, RandomState instance or None, default=None
        Controls both the randomness of the bootstrapping of the samples used
        when building trees (if ``bootstrap=True``) and the sampling of the
        features to consider when looking for the best split at each node
        (if ``max_features < n_features``).
        See :term:`Glossary <random_state>` for details.

    verbose : int, default=0
        Controls the verbosity when fitting and predicting.

    warm_start : bool, default=False
        When set to ``True``, reuse the solution of the previous call to fit
        and add more estimators to the ensemble, otherwise, just fit a whole
        new forest. See :term:`the Glossary <warm_start>`.

    class_weight : {"balanced", "balanced_subsample"}, dict or list of dicts, \
            default=None
        Weights associated with classes in the form ``{class_label: weight}``.
        If not given, all classes are supposed to have weight one. For
        multi-output problems, a list of dicts can be provided in the same
        order as the columns of y.

        Note that for multioutput (including multilabel) weights should be
        defined for each class of every column in its own dict. For example,
        for four-class multilabel classification weights should be
        [{0: 1, 1: 1}, {0: 1, 1: 5}, {0: 1, 1: 1}, {0: 1, 1: 1}] instead of
        [{1:1}, {2:5}, {3:1}, {4:1}].

        The "balanced" mode uses the values of y to automatically adjust
        weights inversely proportional to class frequencies in the input data
        as ``n_samples / (n_classes * np.bincount(y))``

        The "balanced_subsample" mode is the same as "balanced" except that
        weights are computed based on the bootstrap sample for every tree
        grown.

        For multi-output, the weights of each column of y will be multiplied.

        Note that these weights will be multiplied with sample_weight (passed
        through the fit method) if sample_weight is specified.

    max_samples : int or float, default=None
        If bootstrap is True, the number of samples to draw from X
        to train each base estimator.

        - If None (default), then draw `X.shape[0]` samples.
        - If int, then draw `max_samples` samples.
        - If float, then draw `max_samples * X.shape[0]` samples. Thus,
          `max_samples` should be in the interval `(0.0, 1.0]`.

    feature_combinations : float, default=None
        The number of features to combine on average at each split
        of the decision trees. If ``None``, then will default to the minimum of
        ``(1.5, n_features)``. This controls the number of non-zeros is the
        projection matrix. Setting the value to 1.0 is equivalent to a
        traditional decision-tree. ``feature_combinations * max_features``
        gives the number of expected non-zeros in the projection matrix of shape
        ``(max_features, n_features)``. Thus this value must always be less than
        ``n_features`` in order to be valid.

    Attributes
    ----------
    base_estimator_ : sktree.tree.ObliqueDecisionTreeClassifier
        The child estimator template used to create the collection of fitted
        sub-estimators.

    estimators_ : list of sktree.tree.ObliqueDecisionTreeClassifier
        The collection of fitted sub-estimators.

    classes_ : ndarray of shape (n_classes,) or a list of such arrays
        The classes labels (single output problem), or a list of arrays of
        class labels (multi-output problem).

    n_classes_ : int or list
        The number of classes (single output problem), or a list containing the
        number of classes for each output (multi-output problem).

    n_features_ : int
        The number of features when ``fit`` is performed.

    n_features_in_ : int
        Number of features seen during :term:`fit`.

    feature_names_in_ : ndarray of shape (`n_features_in_`,)
        Names of features seen during :term:`fit`. Defined only when `X`
        has feature names that are all strings.

    n_outputs_ : int
        The number of outputs when ``fit`` is performed.

    feature_importances_ : ndarray of shape (n_features,)
        The impurity-based feature importances.
        The higher, the more important the feature.
        The importance of a feature is computed as the (normalized)
        total reduction of the criterion brought by that feature.  It is also
        known as the Gini importance.

        Warning: impurity-based feature importances can be misleading for
        high cardinality features (many unique values). See
        :func:`sklearn.inspection.permutation_importance` as an alternative.

    oob_score_ : float
        Score of the training dataset obtained using an out-of-bag estimate.
        This attribute exists only when ``oob_score`` is True.

    oob_decision_function_ : ndarray of shape (n_samples, n_classes) or \
            (n_samples, n_classes, n_outputs)
        Decision function computed with out-of-bag estimate on the training
        set. If n_estimators is small it might be possible that a data point
        was never left out during the bootstrap. In this case,
        `oob_decision_function_` might contain NaN. This attribute exists
        only when ``oob_score`` is True.

    See Also
    --------
    sktree.tree.ObliqueDecisionTreeClassifier : An oblique decision
        tree classifier.
    sklearn.ensemble.RandomForestClassifier : An axis-aligned decision
        forest classifier.

    Notes
    -----
    The default values for the parameters controlling the size of the trees
    (e.g. ``max_depth``, ``min_samples_leaf``, etc.) lead to fully grown and
    unpruned trees which can potentially be very large on some data sets. To
    reduce memory consumption, the complexity and size of the trees should be
    controlled by setting those parameter values.

    The features are always randomly permuted at each split. Therefore,
    the best found split may vary, even with the same training data,
    ``max_features=n_features`` and ``bootstrap=False``, if the improvement
    of the criterion is identical for several splits enumerated during the
    search of the best split. To obtain a deterministic behaviour during
    fitting, ``random_state`` has to be fixed.

    References
    ----------
    .. [1] L. Breiman, "Random Forests", Machine Learning, 45(1), 5-32, 2001.

    Examples
    --------
    >>> from sktree.ensemble import ObliqueRandomForestClassifier
    >>> from sklearn.datasets import make_classification
    >>> X, y = make_classification(n_samples=1000, n_features=4,
    ...                            n_informative=2, n_redundant=0,
    ...                            random_state=0, shuffle=False)
    >>> clf = ObliqueRandomForestClassifier(max_depth=2, random_state=0)
    >>> clf.fit(X, y)
    ObliqueRandomForestClassifier(...)
    >>> print(clf.predict([[0, 0, 0, 0]]))
    [1]
    """

    tree_type = "oblique"
    _parameter_constraints: dict = {
        **ForestClassifier._parameter_constraints,
        **ObliqueDecisionTreeClassifier._parameter_constraints,
        "class_weight": [
            StrOptions({"balanced_subsample", "balanced"}),
            dict,
            list,
            None,
        ],
    }
    _parameter_constraints.pop("splitter")

    def __init__(
        self,
        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=True,
        oob_score=False,
        n_jobs=None,
        random_state=None,
        verbose=0,
        warm_start=False,
        class_weight=None,
        max_samples=None,
        feature_combinations=None,
    ):
        super().__init__(
            estimator=ObliqueDecisionTreeClassifier(),
            n_estimators=n_estimators,
            estimator_params=(
                "criterion",
                "max_depth",
                "min_samples_split",
                "min_samples_leaf",
                "min_weight_fraction_leaf",
                "max_features",
                "max_leaf_nodes",
                "min_impurity_decrease",
                "random_state",
                "feature_combinations",
            ),
            bootstrap=bootstrap,
            oob_score=oob_score,
            n_jobs=n_jobs,
            random_state=random_state,
            verbose=verbose,
            warm_start=warm_start,
            class_weight=class_weight,
            max_samples=max_samples,
        )
        self.criterion = criterion
        self.max_depth = max_depth
        self.min_samples_split = min_samples_split
        self.min_samples_leaf = min_samples_leaf
        self.max_features = max_features
        self.feature_combinations = feature_combinations

        # unused by oblique forests
        self.min_weight_fraction_leaf = min_weight_fraction_leaf
        self.max_leaf_nodes = max_leaf_nodes
        self.min_impurity_decrease = min_impurity_decrease


class ObliqueRandomForestRegressor(SimMatrixMixin, ForestRegressor):
    """An oblique random forest regressor.

    A oblique random forest is a meta estimator similar to a random
    forest that fits a number of oblique decision tree regressor
    on various sub-samples of the dataset and uses averaging to
    improve the predictive accuracy and control over-fitting.

    The sub-sample size is controlled with the `max_samples` parameter if
    `bootstrap=True` (default), otherwise the whole dataset is used to build
    each tree.

    Read more in the :ref:`User Guide <sklearn:forest>`.

    Parameters
    ----------
    n_estimators : int, default=100
        The number of trees in the forest.

    criterion : {"squared_error", "absolute_error", "friedman_mse", "poisson"}, \
            default="squared_error"

        The function to measure the quality of a split. Supported criteria
        are "squared_error" for the mean squared error, which is equal to
        variance reduction as feature selection criterion and minimizes the L2
        loss using the mean of each terminal node, "friedman_mse", which uses
        mean squared error with Friedman's improvement score for potential
        splits, "absolute_error" for the mean absolute error, which minimizes
        the L1 loss using the median of each terminal node, and "poisson" which
        uses reduction in Poisson deviance to find splits.
        Training using "absolute_error" is significantly slower
        than when using "squared_error".

    max_depth : int, default=None
        The maximum depth of the tree. If None, then nodes are expanded until
        all leaves are pure or until all leaves contain less than
        min_samples_split samples.

    min_samples_split : int or float, default=2
        The minimum number of samples required to split an internal node:

        - If int, then consider `min_samples_split` as the minimum number.
        - If float, then `min_samples_split` is a fraction and
          `ceil(min_samples_split * n_samples)` are the minimum
          number of samples for each split.

    min_samples_leaf : int or float, default=1
        The minimum number of samples required to be at a leaf node.
        A split point at any depth will only be considered if it leaves at
        least ``min_samples_leaf`` training samples in each of the left and
        right branches.  This may have the effect of smoothing the model,
        especially in regression.

        - If int, then consider `min_samples_leaf` as the minimum number.
        - If float, then `min_samples_leaf` is a fraction and
          `ceil(min_samples_leaf * n_samples)` are the minimum
          number of samples for each node.

    min_weight_fraction_leaf : float, default=0.0
        The minimum weighted fraction of the sum total of weights (of all
        the input samples) required to be at a leaf node. Samples have
        equal weight when sample_weight is not provided.

    max_features : {"sqrt", "log2", None}, int or float, default="sqrt"
        The number of features to consider when looking for the best split:

        - If int, then consider `max_features` features at each split.
        - If float, then `max_features` is a fraction and
          `round(max_features * n_features)` features are considered at each
          split.
        - If "auto", then `max_features=sqrt(n_features)`.
        - If "sqrt", then `max_features=sqrt(n_features)`.
        - If "log2", then `max_features=log2(n_features)`.
        - If None, then `max_features=n_features`.

        Note: the search for a split does not stop until at least one
        valid partition of the node samples is found, even if it requires to
        effectively inspect more than ``max_features`` features.

    max_leaf_nodes : int, default=None
        Grow trees with ``max_leaf_nodes`` in best-first fashion.
        Best nodes are defined as relative reduction in impurity.
        If None then unlimited number of leaf nodes.

    min_impurity_decrease : float, default=0.0
        A node will be split if this split induces a decrease of the impurity
        greater than or equal to this value.

        The weighted impurity decrease equation is the following::

            N_t / N * (impurity - N_t_R / N_t * right_impurity
                                - N_t_L / N_t * left_impurity)

        where ``N`` is the total number of samples, ``N_t`` is the number of
        samples at the current node, ``N_t_L`` is the number of samples in the
        left child, and ``N_t_R`` is the number of samples in the right child.

        ``N``, ``N_t``, ``N_t_R`` and ``N_t_L`` all refer to the weighted sum,
        if ``sample_weight`` is passed.

    bootstrap : bool, default=True
        Whether bootstrap samples are used when building trees. If False, the
        whole dataset is used to build each tree.

    oob_score : bool, default=False
        Whether to use out-of-bag samples to estimate the generalization score.
        Only available if bootstrap=True.

    n_jobs : int, default=None
        The number of jobs to run in parallel. :meth:`fit`, :meth:`predict`,
        :meth:`decision_path` and :meth:`apply` are all parallelized over the
        trees. ``None`` means 1 unless in a `joblib.parallel_backend`
        context. ``-1`` means using all processors. See :term:`Glossary
        <n_jobs>` for more details.

    random_state : int, RandomState instance or None, default=None
        Controls both the randomness of the bootstrapping of the samples used
        when building trees (if ``bootstrap=True``) and the sampling of the
        features to consider when looking for the best split at each node
        (if ``max_features < n_features``).
        See :term:`Glossary <random_state>` for details.

    verbose : int, default=0
        Controls the verbosity when fitting and predicting.

    warm_start : bool, default=False
        When set to ``True``, reuse the solution of the previous call to fit
        and add more estimators to the ensemble, otherwise, just fit a whole
        new forest. See :term:`the Glossary <warm_start>`.

    max_samples : int or float, default=None
        If bootstrap is True, the number of samples to draw from X
        to train each base estimator.

        - If None (default), then draw `X.shape[0]` samples.
        - If int, then draw `max_samples` samples.
        - If float, then draw `max_samples * X.shape[0]` samples. Thus,
          `max_samples` should be in the interval `(0.0, 1.0]`.

    feature_combinations : float, default=None
        The number of features to combine on average at each split
        of the decision trees. If ``None``, then will default to the minimum of
        ``(1.5, n_features)``. This controls the number of non-zeros is the
        projection matrix. Setting the value to 1.0 is equivalent to a
        traditional decision-tree. ``feature_combinations * max_features``
        gives the number of expected non-zeros in the projection matrix of shape
        ``(max_features, n_features)``. Thus this value must always be less than
        ``n_features`` in order to be valid.

    Attributes
    ----------
    base_estimator_ : ObliqueDecisionTreeRegressor
        The child estimator template used to create the collection of fitted
        sub-estimators.

    estimators_ : list of ObliqueDecisionTreeRegressor
        The collection of fitted sub-estimators.

    n_features_ : int
        The number of features when ``fit`` is performed.

    n_features_in_ : int
        Number of features seen during :term:`fit`.

    feature_names_in_ : ndarray of shape (`n_features_in_`,)
        Names of features seen during :term:`fit`. Defined only when `X`
        has feature names that are all strings.

    n_outputs_ : int
        The number of outputs when ``fit`` is performed.

    feature_importances_ : ndarray of shape (n_features,)
        The impurity-based feature importances.
        The higher, the more important the feature.
        The importance of a feature is computed as the (normalized)
        total reduction of the criterion brought by that feature.  It is also
        known as the Gini importance.

        Warning: impurity-based feature importances can be misleading for
        high cardinality features (many unique values). See
        :func:`sklearn.inspection.permutation_importance` as an alternative.

    oob_score_ : float
        Score of the training dataset obtained using an out-of-bag estimate.
        This attribute exists only when ``oob_score`` is True.

    oob_decision_function_ : ndarray of shape (n_samples, n_classes) or \
            (n_samples, n_classes, n_outputs)
        Decision function computed with out-of-bag estimate on the training
        set. If n_estimators is small it might be possible that a data point
        was never left out during the bootstrap. In this case,
        `oob_decision_function_` might contain NaN. This attribute exists
        only when ``oob_score`` is True.

    See Also
    --------
    sktree.tree.ObliqueDecisionTreeRegressor : An oblique decision
        tree regressor.
    sklearn.ensemble.RandomForestRegressor : An axis-aligned decision
        forest regressor.

    Notes
    -----
    The default values for the parameters controlling the size of the trees
    (e.g. ``max_depth``, ``min_samples_leaf``, etc.) lead to fully grown and
    unpruned trees which can potentially be very large on some data sets. To
    reduce memory consumption, the complexity and size of the trees should be
    controlled by setting those parameter values.

    The features are always randomly permuted at each split. Therefore,
    the best found split may vary, even with the same training data,
    ``max_features=n_features`` and ``bootstrap=False``, if the improvement
    of the criterion is identical for several splits enumerated during the
    search of the best split. To obtain a deterministic behaviour during
    fitting, ``random_state`` has to be fixed.

    References
    ----------
    .. [1] L. Breiman, "Random Forests", Machine Learning, 45(1), 5-32, 2001.

    .. [2] T. Tomita, "Sparse Projection Oblique Randomer Forests", \
        Journal of Machine Learning Research, 21(104), 1-39, 2020.

    Examples
    --------
    >>> from sktree.ensemble import ObliqueRandomForestRegressor
    >>> from sklearn.datasets import make_regression
    >>> X, y = make_regression(n_features=4, n_informative=2,
    ...                        random_state=0, shuffle=False)
    >>> regr = ObliqueRandomForestRegressor(max_depth=2, random_state=0)
    >>> regr.fit(X, y)
    ObliqueRandomForestRegressor(...)
    >>> print(regr.predict([[0, 0, 0, 0]]))
    [-5.86327109]
    """

    tree_type = "oblique"
    _parameter_constraints: dict = {
        **ForestRegressor._parameter_constraints,
        **ObliqueDecisionTreeRegressor._parameter_constraints,
    }
    _parameter_constraints.pop("splitter")

    def __init__(
        self,
        n_estimators=100,
        *,
        criterion="squared_error",
        max_depth=None,
        min_samples_split=2,
        min_samples_leaf=1,
        min_weight_fraction_leaf=0.0,
        max_features=1.0,
        max_leaf_nodes=None,
        min_impurity_decrease=0.0,
        bootstrap=True,
        oob_score=False,
        n_jobs=None,
        random_state=None,
        verbose=0,
        warm_start=False,
        max_samples=None,
        feature_combinations=None,
    ):
        super().__init__(
            estimator=ObliqueDecisionTreeRegressor(),
            n_estimators=n_estimators,
            estimator_params=(
                "criterion",
                "max_depth",
                "min_samples_split",
                "min_samples_leaf",
                "min_weight_fraction_leaf",
                "max_features",
                "max_leaf_nodes",
                "min_impurity_decrease",
                "random_state",
                "feature_combinations",
            ),
            bootstrap=bootstrap,
            oob_score=oob_score,
            n_jobs=n_jobs,
            random_state=random_state,
            verbose=verbose,
            warm_start=warm_start,
            max_samples=max_samples,
        )
        self.criterion = criterion
        self.max_depth = max_depth
        self.min_samples_split = min_samples_split
        self.min_samples_leaf = min_samples_leaf
        self.min_weight_fraction_leaf = min_weight_fraction_leaf
        self.max_features = max_features
        self.max_leaf_nodes = max_leaf_nodes
        self.min_impurity_decrease = min_impurity_decrease
        self.feature_combinations = feature_combinations

        # unused by oblique forests
        self.min_weight_fraction_leaf = min_weight_fraction_leaf
        self.max_leaf_nodes = max_leaf_nodes
        self.min_impurity_decrease = min_impurity_decrease


class PatchObliqueRandomForestClassifier(SimMatrixMixin, ForestClassifier):
    """A patch-oblique random forest classifier.

    A patch-oblique random forest is a meta estimator similar to a random
    forest that fits a number of patch oblique decision tree classifiers
    on various sub-samples of the dataset and uses averaging to
    improve the predictive accuracy and control over-fitting. For more
    details, see :footcite:`Li2019manifold`.

    Parameters
    ----------
    n_estimators : int, default=100
        The number of trees in the forest.

    criterion : {"gini", "entropy"}, default="gini"
        The function to measure the quality of a split. Supported criteria are
        "gini" for the Gini impurity and "entropy" for the information gain.
        Note: this parameter is tree-specific.

    max_depth : int, default=None
        The maximum depth of the tree. If None, then nodes are expanded until
        all leaves are pure or until all leaves contain less than
        min_samples_split samples.

    min_samples_split : int or float, default=2
        The minimum number of samples required to split an internal node:

        - If int, then consider `min_samples_split` as the minimum number.
        - If float, then `min_samples_split` is a fraction and
          `ceil(min_samples_split * n_samples)` are the minimum
          number of samples for each split.

    min_samples_leaf : int or float, default=1
        The minimum number of samples required to be at a leaf node.
        A split point at any depth will only be considered if it leaves at
        least ``min_samples_leaf`` training samples in each of the left and
        right branches.  This may have the effect of smoothing the model,
        especially in regression.

        - If int, then consider `min_samples_leaf` as the minimum number.
        - If float, then `min_samples_leaf` is a fraction and
          `ceil(min_samples_leaf * n_samples)` are the minimum
          number of samples for each node.

    min_weight_fraction_leaf : float, default=0.0
        The minimum weighted fraction of the sum total of weights (of all
        the input samples) required to be at a leaf node. Samples have
        equal weight when sample_weight is not provided.

    max_features : {"sqrt", "log2", None}, int or float, default="sqrt"
        The number of features to consider when looking for the best split:

        - If int, then consider `max_features` features at each split.
        - If float, then `max_features` is a fraction and
          `round(max_features * n_features)` features are considered at each
          split.
        - If "auto", then `max_features=sqrt(n_features)`.
        - If "sqrt", then `max_features=sqrt(n_features)`.
        - If "log2", then `max_features=log2(n_features)`.
        - If None, then `max_features=n_features`.

        Note: the search for a split does not stop until at least one
        valid partition of the node samples is found, even if it requires to
        effectively inspect more than ``max_features`` features.

    max_leaf_nodes : int, default=None
        Grow trees with ``max_leaf_nodes`` in best-first fashion.
        Best nodes are defined as relative reduction in impurity.
        If None then unlimited number of leaf nodes.

    min_impurity_decrease : float, default=0.0
        A node will be split if this split induces a decrease of the impurity
        greater than or equal to this value.

        The weighted impurity decrease equation is the following::

            N_t / N * (impurity - N_t_R / N_t * right_impurity
                                - N_t_L / N_t * left_impurity)

        where ``N`` is the total number of samples, ``N_t`` is the number of
        samples at the current node, ``N_t_L`` is the number of samples in the
        left child, and ``N_t_R`` is the number of samples in the right child.

        ``N``, ``N_t``, ``N_t_R`` and ``N_t_L`` all refer to the weighted sum,
        if ``sample_weight`` is passed.

    bootstrap : bool, default=True
        Whether bootstrap samples are used when building trees. If False, the
        whole dataset is used to build each tree.

    oob_score : bool, default=False
        Whether to use out-of-bag samples to estimate the generalization score.
        Only available if bootstrap=True.

    n_jobs : int, default=None
        The number of jobs to run in parallel. :meth:`fit`, :meth:`predict`,
        :meth:`decision_path` and :meth:`apply` are all parallelized over the
        trees. ``None`` means 1 unless in a `joblib.parallel_backend`
        context. ``-1`` means using all processors. See :term:`Glossary
        <n_jobs>` for more details.

    random_state : int, RandomState instance or None, default=None
        Controls both the randomness of the bootstrapping of the samples used
        when building trees (if ``bootstrap=True``) and the sampling of the
        features to consider when looking for the best split at each node
        (if ``max_features < n_features``).
        See :term:`Glossary <random_state>` for details.

    verbose : int, default=0
        Controls the verbosity when fitting and predicting.

    warm_start : bool, default=False
        When set to ``True``, reuse the solution of the previous call to fit
        and add more estimators to the ensemble, otherwise, just fit a whole
        new forest. See :term:`the Glossary <warm_start>`.

    class_weight : {"balanced", "balanced_subsample"}, dict or list of dicts, \
            default=None
        Weights associated with classes in the form ``{class_label: weight}``.
        If not given, all classes are supposed to have weight one. For
        multi-output problems, a list of dicts can be provided in the same
        order as the columns of y.

        Note that for multioutput (including multilabel) weights should be
        defined for each class of every column in its own dict. For example,
        for four-class multilabel classification weights should be
        [{0: 1, 1: 1}, {0: 1, 1: 5}, {0: 1, 1: 1}, {0: 1, 1: 1}] instead of
        [{1:1}, {2:5}, {3:1}, {4:1}].

        The "balanced" mode uses the values of y to automatically adjust
        weights inversely proportional to class frequencies in the input data
        as ``n_samples / (n_classes * np.bincount(y))``

        The "balanced_subsample" mode is the same as "balanced" except that
        weights are computed based on the bootstrap sample for every tree
        grown.

        For multi-output, the weights of each column of y will be multiplied.

        Note that these weights will be multiplied with sample_weight (passed
        through the fit method) if sample_weight is specified.

    max_samples : int or float, default=None
        If bootstrap is True, the number of samples to draw from X
        to train each base estimator.

        - If None (default), then draw `X.shape[0]` samples.
        - If int, then draw `max_samples` samples.
        - If float, then draw `max_samples * X.shape[0]` samples. Thus,
          `max_samples` should be in the interval `(0.0, 1.0]`.

    min_patch_dims : array-like, optional
        The minimum dimensions of a patch, by default 1 along all dimensions.

    max_patch_dims : array-like, optional
        The maximum dimensions of a patch, by default 1 along all dimensions.

    dim_contiguous : array-like of bool, optional
        Whether or not each patch is sampled contiguously along this dimension.

    data_dims : array-like, optional
        The presumed dimensions of the un-vectorized feature vector, by default
        will be a 1D vector with (1, n_features) shape.

    boundary : optional, str {'wrap'}
        The boundary condition to use when sampling patches, by default None.
        'wrap' corresponds to the boundary condition as is in numpy and scipy.

    feature_weight : array-like of shape (n_features,), default=None
        Feature weights. If None, then features are equally weighted as is.
        If provided, then the feature weights are used to weight the
        patches that are generated. The feature weights are used
        as follows: for every patch that is sampled, the feature weights over
        the entire patch is summed and normalizes the patch.

    Attributes
    ----------
    base_estimator_ : PatchObliqueDecisionTreeClassifier
        The child estimator template used to create the collection of fitted
        sub-estimators.

    estimators_ : list of PatchObliqueDecisionTreeClassifier
        The collection of fitted sub-estimators.

    classes_ : ndarray of shape (n_classes,) or a list of such arrays
        The classes labels (single output problem), or a list of arrays of
        class labels (multi-output problem).

    n_classes_ : int or list
        The number of classes (single output problem), or a list containing the
        number of classes for each output (multi-output problem).

    n_features_ : int
        The number of features when ``fit`` is performed.

    n_features_in_ : int
        Number of features seen during :term:`fit`.

    feature_names_in_ : ndarray of shape (`n_features_in_`,)
        Names of features seen during :term:`fit`. Defined only when `X`
        has feature names that are all strings.

    n_outputs_ : int
        The number of outputs when ``fit`` is performed.

    feature_importances_ : ndarray of shape (n_features,)
        The impurity-based feature importances.
        The higher, the more important the feature.
        The importance of a feature is computed as the (normalized)
        total reduction of the criterion brought by that feature.  It is also
        known as the Gini importance.

        Warning: impurity-based feature importances can be misleading for
        high cardinality features (many unique values). See
        :func:`sklearn.inspection.permutation_importance` as an alternative.

    oob_score_ : float
        Score of the training dataset obtained using an out-of-bag estimate.
        This attribute exists only when ``oob_score`` is True.

    oob_decision_function_ : ndarray of shape (n_samples, n_classes) or \
            (n_samples, n_classes, n_outputs)
        Decision function computed with out-of-bag estimate on the training
        set. If n_estimators is small it might be possible that a data point
        was never left out during the bootstrap. In this case,
        `oob_decision_function_` might contain NaN. This attribute exists
        only when ``oob_score`` is True.

    See Also
    --------
    sktree.tree.ObliqueDecisionTreeClassifier : An oblique decision
        tree classifier.
    sklearn.ensemble.RandomForestClassifier : An axis-aligned decision
        forest classifier.

    Notes
    -----
    The default values for the parameters controlling the size of the trees
    (e.g. ``max_depth``, ``min_samples_leaf``, etc.) lead to fully grown and
    unpruned trees which can potentially be very large on some data sets. To
    reduce memory consumption, the complexity and size of the trees should be
    controlled by setting those parameter values.

    The features are always randomly permuted at each split. Therefore,
    the best found split may vary, even with the same training data,
    ``max_features=n_features`` and ``bootstrap=False``, if the improvement
    of the criterion is identical for several splits enumerated during the
    search of the best split. To obtain a deterministic behaviour during
    fitting, ``random_state`` has to be fixed.

    References
    ----------
    .. footbibliography::
    """

    tree_type = "oblique"
    _parameter_constraints: dict = {
        **ForestClassifier._parameter_constraints,
        **PatchObliqueDecisionTreeClassifier._parameter_constraints,
        "class_weight": [
            StrOptions({"balanced_subsample", "balanced"}),
            dict,
            list,
            None,
        ],
    }
    _parameter_constraints.pop("splitter")

    def __init__(
        self,
        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=True,
        oob_score=False,
        n_jobs=None,
        random_state=None,
        verbose=0,
        warm_start=False,
        class_weight=None,
        max_samples=None,
        min_patch_dims=None,
        max_patch_dims=None,
        dim_contiguous=None,
        data_dims=None,
        boundary=None,
        feature_weight=None,
    ):
        super().__init__(
            estimator=PatchObliqueDecisionTreeClassifier(),
            n_estimators=n_estimators,
            estimator_params=(
                "criterion",
                "max_depth",
                "min_samples_split",
                "min_samples_leaf",
                "min_weight_fraction_leaf",
                "max_features",
                "max_leaf_nodes",
                "min_impurity_decrease",
                "random_state",
                "min_patch_dims",
                "max_patch_dims",
                "dim_contiguous",
                "data_dims",
                "boundary",
                "feature_weight",
            ),
            bootstrap=bootstrap,
            oob_score=oob_score,
            n_jobs=n_jobs,
            random_state=random_state,
            verbose=verbose,
            warm_start=warm_start,
            class_weight=class_weight,
            max_samples=max_samples,
        )
        self.criterion = criterion
        self.max_depth = max_depth
        self.min_samples_split = min_samples_split
        self.min_samples_leaf = min_samples_leaf
        self.max_features = max_features

        self.min_patch_dims = min_patch_dims
        self.max_patch_dims = max_patch_dims
        self.dim_contiguous = dim_contiguous
        self.data_dims = data_dims
        self.boundary = boundary
        self.feature_weight = feature_weight

        # unused by oblique forests
        self.min_weight_fraction_leaf = min_weight_fraction_leaf
        self.max_leaf_nodes = max_leaf_nodes
        self.min_impurity_decrease = min_impurity_decrease


class PatchObliqueRandomForestRegressor(SimMatrixMixin, ForestRegressor):
    """A patch-oblique random forest regressor.

    A patch-oblique random forest is a meta estimator similar to a random
    forest that fits a number of patch oblique decision tree regressors
    on various sub-samples of the dataset and uses averaging to
    improve the predictive accuracy and control over-fitting. For more
    details, see :footcite:`Li2019manifold`.

    Parameters
    ----------
    n_estimators : int, default=100
        The number of trees in the forest.

    criterion : {"squared_error", "absolute_error", "friedman_mse", "poisson"},\
            default="squared_error"

        The function to measure the quality of a split. Supported criteria
        are "squared_error" for the mean squared error, which is equal to
        variance reduction as feature selection criterion and minimizes the L2
        loss using the mean of each terminal node, "friedman_mse", which uses
        mean squared error with Friedman's improvement score for potential
        splits, "absolute_error" for the mean absolute error, which minimizes
        the L1 loss using the median of each terminal node, and "poisson" which
        uses reduction in Poisson deviance to find splits.
        Training using "absolute_error" is significantly slower
        than when using "squared_error".

    max_depth : int, default=None
        The maximum depth of the tree. If None, then nodes are expanded until
        all leaves are pure or until all leaves contain less than
        min_samples_split samples.

    min_samples_split : int or float, default=2
        The minimum number of samples required to split an internal node:

        - If int, then consider `min_samples_split` as the minimum number.
        - If float, then `min_samples_split` is a fraction and
          `ceil(min_samples_split * n_samples)` are the minimum
          number of samples for each split.

    min_samples_leaf : int or float, default=1
        The minimum number of samples required to be at a leaf node.
        A split point at any depth will only be considered if it leaves at
        least ``min_samples_leaf`` training samples in each of the left and
        right branches.  This may have the effect of smoothing the model,
        especially in regression.

        - If int, then consider `min_samples_leaf` as the minimum number.
        - If float, then `min_samples_leaf` is a fraction and
          `ceil(min_samples_leaf * n_samples)` are the minimum
          number of samples for each node.

    min_weight_fraction_leaf : float, default=0.0
        The minimum weighted fraction of the sum total of weights (of all
        the input samples) required to be at a leaf node. Samples have
        equal weight when sample_weight is not provided.

    max_features : {"sqrt", "log2", None}, int or float, default="sqrt"
        The number of features to consider when looking for the best split:

        - If int, then consider `max_features` features at each split.
        - If float, then `max_features` is a fraction and
          `round(max_features * n_features)` features are considered at each
          split.
        - If "auto", then `max_features=sqrt(n_features)`.
        - If "sqrt", then `max_features=sqrt(n_features)`.
        - If "log2", then `max_features=log2(n_features)`.
        - If None, then `max_features=n_features`.

        Note: the search for a split does not stop until at least one
        valid partition of the node samples is found, even if it requires to
        effectively inspect more than ``max_features`` features.

    max_leaf_nodes : int, default=None
        Grow trees with ``max_leaf_nodes`` in best-first fashion.
        Best nodes are defined as relative reduction in impurity.
        If None then unlimited number of leaf nodes.

    min_impurity_decrease : float, default=0.0
        A node will be split if this split induces a decrease of the impurity
        greater than or equal to this value.

        The weighted impurity decrease equation is the following::

            N_t / N * (impurity - N_t_R / N_t * right_impurity
                                - N_t_L / N_t * left_impurity)

        where ``N`` is the total number of samples, ``N_t`` is the number of
        samples at the current node, ``N_t_L`` is the number of samples in the
        left child, and ``N_t_R`` is the number of samples in the right child.

        ``N``, ``N_t``, ``N_t_R`` and ``N_t_L`` all refer to the weighted sum,
        if ``sample_weight`` is passed.

    bootstrap : bool, default=True
        Whether bootstrap samples are used when building trees. If False, the
        whole dataset is used to build each tree.

    oob_score : bool, default=False
        Whether to use out-of-bag samples to estimate the generalization score.
        Only available if bootstrap=True.

    n_jobs : int, default=None
        The number of jobs to run in parallel. :meth:`fit`, :meth:`predict`,
        :meth:`decision_path` and :meth:`apply` are all parallelized over the
        trees. ``None`` means 1 unless in a `joblib.parallel_backend`
        context. ``-1`` means using all processors. See :term:`Glossary
        <n_jobs>` for more details.

    random_state : int, RandomState instance or None, default=None
        Controls both the randomness of the bootstrapping of the samples used
        when building trees (if ``bootstrap=True``) and the sampling of the
        features to consider when looking for the best split at each node
        (if ``max_features < n_features``).
        See :term:`Glossary <random_state>` for details.

    verbose : int, default=0
        Controls the verbosity when fitting and predicting.

    warm_start : bool, default=False
        When set to ``True``, reuse the solution of the previous call to fit
        and add more estimators to the ensemble, otherwise, just fit a whole
        new forest. See :term:`the Glossary <warm_start>`.

    max_samples : int or float, default=None
        If bootstrap is True, the number of samples to draw from X
        to train each base estimator.

        - If None (default), then draw `X.shape[0]` samples.
        - If int, then draw `max_samples` samples.
        - If float, then draw `max_samples * X.shape[0]` samples. Thus,
          `max_samples` should be in the interval `(0.0, 1.0]`.

    min_patch_dims : array-like, optional
        The minimum dimensions of a patch, by default 1 along all dimensions.

    max_patch_dims : array-like, optional
        The maximum dimensions of a patch, by default 1 along all dimensions.

    dim_contiguous : array-like of bool, optional
        Whether or not each patch is sampled contiguously along this dimension.

    data_dims : array-like, optional
        The presumed dimensions of the un-vectorized feature vector, by default
        will be a 1D vector with (1, n_features) shape.

    boundary : optional, str {'wrap'}
        The boundary condition to use when sampling patches, by default None.
        'wrap' corresponds to the boundary condition as is in numpy and scipy.

    feature_weight : array-like of shape (n_features,), default=None
        Feature weights. If None, then features are equally weighted as is.
        If provided, then the feature weights are used to weight the
        patches that are generated. The feature weights are used
        as follows: for every patch that is sampled, the feature weights over
        the entire patch is summed and normalizes the patch.

    Attributes
    ----------
    base_estimator_ : PatchObliqueDecisionTreeRegressor
        The child estimator template used to create the collection of fitted
        sub-estimators.

    estimators_ : list of PatchObliqueDecisionTreeRegressor
        The collection of fitted sub-estimators.

    n_features_ : int
        The number of features when ``fit`` is performed.

    n_features_in_ : int
        Number of features seen during :term:`fit`.

    feature_names_in_ : ndarray of shape (`n_features_in_`,)
        Names of features seen during :term:`fit`. Defined only when `X`
        has feature names that are all strings.

    n_outputs_ : int
        The number of outputs when ``fit`` is performed.

    feature_importances_ : ndarray of shape (n_features,)
        The impurity-based feature importances.
        The higher, the more important the feature.
        The importance of a feature is computed as the (normalized)
        total reduction of the criterion brought by that feature.  It is also
        known as the Gini importance.

        Warning: impurity-based feature importances can be misleading for
        high cardinality features (many unique values). See
        :func:`sklearn.inspection.permutation_importance` as an alternative.

    oob_score_ : float
        Score of the training dataset obtained using an out-of-bag estimate.
        This attribute exists only when ``oob_score`` is True.

    oob_prediction_ : ndarray of shape (n_samples,) or (n_samples, n_outputs)
        Prediction computed with out-of-bag estimate on the training set.
        This attribute exists only when ``oob_score`` is True.

    See Also
    --------
    sktree.tree.ObliqueDecisionTreeRegressor : An oblique decision
        tree regressor.
    sklearn.ensemble.RandomForestRegressor : An axis-aligned decision
        forest regressor.

    Notes
    -----
    The default values for the parameters controlling the size of the trees
    (e.g. ``max_depth``, ``min_samples_leaf``, etc.) lead to fully grown and
    unpruned trees which can potentially be very large on some data sets. To
    reduce memory consumption, the complexity and size of the trees should be
    controlled by setting those parameter values.
    The features are always randomly permuted at each split. Therefore,
    the best found split may vary, even with the same training data,
    ``max_features=n_features`` and ``bootstrap=False``, if the improvement
    of the criterion is identical for several splits enumerated during the
    search of the best split. To obtain a deterministic behaviour during
    fitting, ``random_state`` has to be fixed.

    References
    ----------
    .. footbibliography::

    Examples
    --------
    >>> from sktree.ensemble import PatchObliqueRandomForestRegressor
    >>> from sklearn.datasets import make_regression
    >>> X, y = make_regression(n_features=4, n_informative=2,
    ...                        random_state=0, shuffle=False)
    >>> regressor = PatchObliqueRandomForestRegressor(max_depth=2, random_state=0)
    >>> regressor.fit(X, y)
    PatchObliqueRandomForestRegressor(...)
    >>> print(regressor.predict([[0, 0, 0, 0]]))
    [-5.82818509]
    """

    tree_type = "oblique"
    _parameter_constraints: dict = {
        **ForestRegressor._parameter_constraints,
        **PatchObliqueDecisionTreeRegressor._parameter_constraints,
    }
    _parameter_constraints.pop("splitter")

    def __init__(
        self,
        n_estimators=100,
        *,
        criterion="squared_error",
        max_depth=None,
        min_samples_split=2,
        min_samples_leaf=1,
        min_weight_fraction_leaf=0.0,
        max_features=1.0,
        max_leaf_nodes=None,
        min_impurity_decrease=0.0,
        bootstrap=True,
        oob_score=False,
        n_jobs=None,
        random_state=None,
        verbose=0,
        warm_start=False,
        max_samples=None,
        min_patch_dims=None,
        max_patch_dims=None,
        dim_contiguous=None,
        data_dims=None,
        boundary=None,
        feature_weight=None,
    ):
        super().__init__(
            estimator=PatchObliqueDecisionTreeRegressor(),
            n_estimators=n_estimators,
            estimator_params=(
                "criterion",
                "max_depth",
                "min_samples_split",
                "min_samples_leaf",
                "min_weight_fraction_leaf",
                "max_features",
                "max_leaf_nodes",
                "min_impurity_decrease",
                "random_state",
                "min_patch_dims",
                "max_patch_dims",
                "dim_contiguous",
                "data_dims",
                "boundary",
                "feature_weight",
            ),
            bootstrap=bootstrap,
            oob_score=oob_score,
            n_jobs=n_jobs,
            random_state=random_state,
            verbose=verbose,
            warm_start=warm_start,
            max_samples=max_samples,
        )
        self.criterion = criterion
        self.max_depth = max_depth
        self.min_samples_split = min_samples_split
        self.min_samples_leaf = min_samples_leaf
        self.max_features = max_features

        self.min_patch_dims = min_patch_dims
        self.max_patch_dims = max_patch_dims
        self.dim_contiguous = dim_contiguous
        self.data_dims = data_dims
        self.boundary = boundary
        self.feature_weight = feature_weight

        # unused by oblique forests
        self.min_weight_fraction_leaf = min_weight_fraction_leaf
        self.max_leaf_nodes = max_leaf_nodes
        self.min_impurity_decrease = min_impurity_decrease
