Help on class RandomForestClassifier in module sklearn.ensemble._forest:
class RandomForestClassifier(ForestClassifier)
| RandomForestClassifier(n_estimators=100, *, criterion='gini', max_depth=None, min_samples_split=2, min_samples_leaf=1, min_weight_fraction_leaf=0.0, max_features='auto', 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, ccp_alpha=0.0, max_samples=None)
|
| A random forest classifier.
|
| A random forest is a meta estimator that fits a number of 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 <forest>`.
|
| Parameters
| ----------
| n_estimators : int, default=100
| The number of trees in the forest.
|
| .. versionchanged:: 0.22
| The default value of ``n_estimators`` changed from 10 to 100
| in 0.22.
|
| 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.
|
| .. versionchanged:: 0.18
| Added float values for fractions.
|
| 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.
|
| .. versionchanged:: 0.18
| Added float values for fractions.
|
| 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 : {"auto", "sqrt", "log2"}, int or float, default="auto"
| 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)` (same as "auto").
| - 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.
|
| .. versionadded:: 0.19
|
| 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 :obj:`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.
|
| ccp_alpha : non-negative float, default=0.0
| Complexity parameter used for Minimal Cost-Complexity Pruning. The
| subtree with the largest cost complexity that is smaller than
| ``ccp_alpha`` will be chosen. By default, no pruning is performed. See
| :ref:`minimal_cost_complexity_pruning` for details.
|
| .. versionadded:: 0.22
|
| 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]`.
|
| .. versionadded:: 0.22
|
| Attributes
| ----------
| base_estimator_ : DecisionTreeClassifier
| The child estimator template used to create the collection of fitted
| sub-estimators.
|
| estimators_ : list of DecisionTreeClassifier
| 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.
|
| .. deprecated:: 1.0
| Attribute `n_features_` was deprecated in version 1.0 and will be
| removed in 1.2. Use `n_features_in_` instead.
|
| n_features_in_ : int
| Number of features seen during :term:`fit`.
|
| .. versionadded:: 0.24
|
| 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.
| .. versionadded:: 1.0
|
| 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
| --------
| sklearn.tree.DecisionTreeClassifier : A decision tree classifier.
| sklearn.ensemble.ExtraTreesClassifier : Ensemble of extremely randomized
| tree classifiers.
|
| 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 sklearn.ensemble import RandomForestClassifier
| >>> 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 = RandomForestClassifier(max_depth=2, random_state=0)
| >>> clf.fit(X, y)
| RandomForestClassifier(...)
| >>> print(clf.predict([[0, 0, 0, 0]]))
| [1]
|
| Method resolution order:
| RandomForestClassifier
| ForestClassifier
| sklearn.base.ClassifierMixin
| BaseForest
| sklearn.base.MultiOutputMixin
| sklearn.ensemble._base.BaseEnsemble
| sklearn.base.MetaEstimatorMixin
| sklearn.base.BaseEstimator
| builtins.object
|
| Methods defined here:
|
| __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='auto', 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, ccp_alpha=0.0, max_samples=None)
| Initialize self. See help(type(self)) for accurate signature.
|
| ----------------------------------------------------------------------
| Data and other attributes defined here:
|
| __abstractmethods__ = frozenset()
|
| ----------------------------------------------------------------------
| Methods inherited from ForestClassifier:
|
| predict(self, X)
| Predict class for X.
|
| The predicted class of an input sample is a vote by the trees in
| the forest, weighted by their probability estimates. That is,
| the predicted class is the one with highest mean probability
| estimate across the trees.
|
| Parameters
| ----------
| X : {array-like, sparse matrix} of shape (n_samples, n_features)
| The input samples. Internally, its dtype will be converted to
| ``dtype=np.float32``. If a sparse matrix is provided, it will be
| converted into a sparse ``csr_matrix``.
|
| Returns
| -------
| y : ndarray of shape (n_samples,) or (n_samples, n_outputs)
| The predicted classes.
|
| predict_log_proba(self, X)
| Predict class log-probabilities for X.
|
| The predicted class log-probabilities of an input sample is computed as
| the log of the mean predicted class probabilities of the trees in the
| forest.
|
| Parameters
| ----------
| X : {array-like, sparse matrix} of shape (n_samples, n_features)
| The input samples. Internally, its dtype will be converted to
| ``dtype=np.float32``. If a sparse matrix is provided, it will be
| converted into a sparse ``csr_matrix``.
|
| Returns
| -------
| p : ndarray of shape (n_samples, n_classes), or a list of such arrays
| The class probabilities of the input samples. The order of the
| classes corresponds to that in the attribute :term:`classes_`.
|
| predict_proba(self, X)
| Predict class probabilities for X.
|
| The predicted class probabilities of an input sample are computed as
| the mean predicted class probabilities of the trees in the forest.
| The class probability of a single tree is the fraction of samples of
| the same class in a leaf.
|
| Parameters
| ----------
| X : {array-like, sparse matrix} of shape (n_samples, n_features)
| The input samples. Internally, its dtype will be converted to
| ``dtype=np.float32``. If a sparse matrix is provided, it will be
| converted into a sparse ``csr_matrix``.
|
| Returns
| -------
| p : ndarray of shape (n_samples, n_classes), or a list of such arrays
| The class probabilities of the input samples. The order of the
| classes corresponds to that in the attribute :term:`classes_`.
|
| ----------------------------------------------------------------------
| Methods inherited from sklearn.base.ClassifierMixin:
|
| score(self, X, y, sample_weight=None)
| Return the mean accuracy on the given test data and labels.
|
| In multi-label classification, this is the subset accuracy
| which is a harsh metric since you require for each sample that
| each label set be correctly predicted.
|
| Parameters
| ----------
| X : array-like of shape (n_samples, n_features)
| Test samples.
|
| y : array-like of shape (n_samples,) or (n_samples, n_outputs)
| True labels for `X`.
|
| sample_weight : array-like of shape (n_samples,), default=None
| Sample weights.
|
| Returns
| -------
| score : float
| Mean accuracy of ``self.predict(X)`` wrt. `y`.
|
| ----------------------------------------------------------------------
| Data descriptors inherited from sklearn.base.ClassifierMixin:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)
|
| ----------------------------------------------------------------------
| Methods inherited from BaseForest:
|
| apply(self, X)
| Apply trees in the forest to X, return leaf indices.
|
| Parameters
| ----------
| X : {array-like, sparse matrix} of shape (n_samples, n_features)
| The input samples. Internally, its dtype will be converted to
| ``dtype=np.float32``. If a sparse matrix is provided, it will be
| converted into a sparse ``csr_matrix``.
|
| Returns
| -------
| X_leaves : ndarray of shape (n_samples, n_estimators)
| For each datapoint x in X and for each tree in the forest,
| return the index of the leaf x ends up in.
|
| decision_path(self, X)
| Return the decision path in the forest.
|
| .. versionadded:: 0.18
|
| Parameters
| ----------
| X : {array-like, sparse matrix} of shape (n_samples, n_features)
| The input samples. Internally, its dtype will be converted to
| ``dtype=np.float32``. If a sparse matrix is provided, it will be
| converted into a sparse ``csr_matrix``.
|
| Returns
| -------
| indicator : sparse matrix of shape (n_samples, n_nodes)
| Return a node indicator matrix where non zero elements indicates
| that the samples goes through the nodes. The matrix is of CSR
| format.
|
| n_nodes_ptr : ndarray of shape (n_estimators + 1,)
| The columns from indicator[n_nodes_ptr[i]:n_nodes_ptr[i+1]]
| gives the indicator value for the i-th estimator.
|
| fit(self, X, y, sample_weight=None)
| Build a forest of trees from the training set (X, y).
|
| Parameters
| ----------
| X : {array-like, sparse matrix} of shape (n_samples, n_features)
| The training input samples. Internally, its dtype will be converted
| to ``dtype=np.float32``. If a sparse matrix is provided, it will be
| converted into a sparse ``csc_matrix``.
|
| y : array-like of shape (n_samples,) or (n_samples, n_outputs)
| The target values (class labels in classification, real numbers in
| regression).
|
| sample_weight : array-like of shape (n_samples,), default=None
| Sample weights. If None, then samples are equally weighted. Splits
| that would create child nodes with net zero or negative weight are
| ignored while searching for a split in each node. In the case of
| classification, splits are also ignored if they would result in any
| single class carrying a negative weight in either child node.
|
| Returns
| -------
| self : object
| Fitted estimator.
|
| ----------------------------------------------------------------------
| Data descriptors inherited from BaseForest:
|
| feature_importances_
| 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.
|
| Returns
| -------
| feature_importances_ : ndarray of shape (n_features,)
| The values of this array sum to 1, unless all trees are single node
| trees consisting of only the root node, in which case it will be an
| array of zeros.
|
| n_features_
| DEPRECATED: Attribute `n_features_` was deprecated in version 1.0 and will be removed in 1.2. Use `n_features_in_` instead.
|
| Number of features when fitting the estimator.
|
| ----------------------------------------------------------------------
| Methods inherited from sklearn.ensemble._base.BaseEnsemble:
|
| __getitem__(self, index)
| Return the index'th estimator in the ensemble.
|
| __iter__(self)
| Return iterator over estimators in the ensemble.
|
| __len__(self)
| Return the number of estimators in the ensemble.
|
| ----------------------------------------------------------------------
| Data and other attributes inherited from sklearn.ensemble._base.BaseEnsemble:
|
| __annotations__ = {'_required_parameters': typing.List[str]}
|
| ----------------------------------------------------------------------
| Methods inherited from sklearn.base.BaseEstimator:
|
| __getstate__(self)
|
| __repr__(self, N_CHAR_MAX=700)
| Return repr(self).
|
| __setstate__(self, state)
|
| get_params(self, deep=True)
| Get parameters for this estimator.
|
| Parameters
| ----------
| deep : bool, default=True
| If True, will return the parameters for this estimator and
| contained subobjects that are estimators.
|
| Returns
| -------
| params : dict
| Parameter names mapped to their values.
|
| set_params(self, **params)
| Set the parameters of this estimator.
|
| The method works on simple estimators as well as on nested objects
| (such as :class:`~sklearn.pipeline.Pipeline`). The latter have
| parameters of the form ``<component>__<parameter>`` so that it's
| possible to update each component of a nested object.
|
| Parameters
| ----------
| **params : dict
| Estimator parameters.
|
| Returns
| -------
| self : estimator instance
| Estimator instance.
