sklearn.ensemble
.RandomTreesEmbedding¶
- class sklearn.ensemble.RandomTreesEmbedding(n_estimators=100, *, max_depth=5, min_samples_split=2, min_samples_leaf=1, min_weight_fraction_leaf=0.0, max_leaf_nodes=None, min_impurity_decrease=0.0, sparse_output=True, n_jobs=None, random_state=None, verbose=0, warm_start=False)[source]¶
An ensemble of totally random trees.
An unsupervised transformation of a dataset to a high-dimensional sparse representation. A datapoint is coded according to which leaf of each tree it is sorted into. Using a one-hot encoding of the leaves, this leads to a binary coding with as many ones as there are trees in the forest.
The dimensionality of the resulting representation is
n_out <= n_estimators * max_leaf_nodes
. Ifmax_leaf_nodes == None
, the number of leaf nodes is at mostn_estimators * 2 ** max_depth
.Read more in the User Guide.
- Parameters:
- n_estimatorsint, default=100
Number of trees in the forest.
Changed in version 0.22: The default value of
n_estimators
changed from 10 to 100 in 0.22.- max_depthint, default=5
The maximum depth of each 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_splitint 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 andceil(min_samples_split * n_samples)
is the minimum number of samples for each split.
Changed in version 0.18: Added float values for fractions.
- min_samples_leafint 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 andceil(min_samples_leaf * n_samples)
is the minimum number of samples for each node.
Changed in version 0.18: Added float values for fractions.
- min_weight_fraction_leaffloat, 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_leaf_nodesint, 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_decreasefloat, 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, andN_t_R
is the number of samples in the right child.N
,N_t
,N_t_R
andN_t_L
all refer to the weighted sum, ifsample_weight
is passed.New in version 0.19.
- sparse_outputbool, default=True
Whether or not to return a sparse CSR matrix, as default behavior, or to return a dense array compatible with dense pipeline operators.
- n_jobsint, default=None
The number of jobs to run in parallel.
fit
,transform
,decision_path
andapply
are all parallelized over the trees.None
means 1 unless in ajoblib.parallel_backend
context.-1
means using all processors. See Glossary for more details.- random_stateint, RandomState instance or None, default=None
Controls the generation of the random
y
used to fit the trees and the draw of the splits for each feature at the trees’ nodes. See Glossary for details.- verboseint, default=0
Controls the verbosity when fitting and predicting.
- warm_startbool, 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 the Glossary.
- Attributes:
- base_estimator_
ExtraTreeClassifier
instance The child estimator template used to create the collection of fitted sub-estimators.
- estimators_list of
ExtraTreeClassifier
instances The collection of fitted sub-estimators.
feature_importances_
ndarray of shape (n_features,)The impurity-based feature importances.
n_features_
intDEPRECATED: Attribute
n_features_
was deprecated in version 1.0 and will be removed in 1.2.- n_features_in_int
Number of features seen during fit.
New in version 0.24.
- feature_names_in_ndarray of shape (
n_features_in_
,) Names of features seen during fit. Defined only when
X
has feature names that are all strings.New in version 1.0.
- n_outputs_int
The number of outputs when
fit
is performed.- one_hot_encoder_OneHotEncoder instance
One-hot encoder used to create the sparse embedding.
- base_estimator_
See also
ExtraTreesClassifier
An extra-trees classifier.
ExtraTreesRegressor
An extra-trees regressor.
RandomForestClassifier
A random forest classifier.
RandomForestRegressor
A random forest regressor.
sklearn.tree.ExtraTreeClassifier
An extremely randomized tree classifier.
sklearn.tree.ExtraTreeRegressor
An extremely randomized tree regressor.
References
[1]P. Geurts, D. Ernst., and L. Wehenkel, “Extremely randomized trees”, Machine Learning, 63(1), 3-42, 2006.
[2]Moosmann, F. and Triggs, B. and Jurie, F. “Fast discriminative visual codebooks using randomized clustering forests” NIPS 2007
Examples
>>> from sklearn.ensemble import RandomTreesEmbedding >>> X = [[0,0], [1,0], [0,1], [-1,0], [0,-1]] >>> random_trees = RandomTreesEmbedding( ... n_estimators=5, random_state=0, max_depth=1).fit(X) >>> X_sparse_embedding = random_trees.transform(X) >>> X_sparse_embedding.toarray() array([[0., 1., 1., 0., 1., 0., 0., 1., 1., 0.], [0., 1., 1., 0., 1., 0., 0., 1., 1., 0.], [0., 1., 0., 1., 0., 1., 0., 1., 0., 1.], [1., 0., 1., 0., 1., 0., 1., 0., 1., 0.], [0., 1., 1., 0., 1., 0., 0., 1., 1., 0.]])
Methods
apply
(X)Apply trees in the forest to X, return leaf indices.
Return the decision path in the forest.
fit
(X[, y, sample_weight])Fit estimator.
fit_transform
(X[, y, sample_weight])Fit estimator and transform dataset.
get_feature_names_out
([input_features])Get output feature names for transformation.
get_params
([deep])Get parameters for this estimator.
set_params
(**params)Set the parameters of this estimator.
transform
(X)Transform dataset.
- apply(X)[source]¶
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 sparsecsr_matrix
.
- Returns:
- X_leavesndarray 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(X)[source]¶
Return the decision path in the forest.
New in version 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 sparsecsr_matrix
.
- Returns:
- indicatorsparse 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_ptrndarray 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.
- property 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
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.
- fit(X, y=None, sample_weight=None)[source]¶
Fit estimator.
- Parameters:
- X{array-like, sparse matrix} of shape (n_samples, n_features)
The input samples. Use
dtype=np.float32
for maximum efficiency. Sparse matrices are also supported, use sparsecsc_matrix
for maximum efficiency.- yIgnored
Not used, present for API consistency by convention.
- sample_weightarray-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:
- selfobject
Returns the instance itself.
- fit_transform(X, y=None, sample_weight=None)[source]¶
Fit estimator and transform dataset.
- Parameters:
- X{array-like, sparse matrix} of shape (n_samples, n_features)
Input data used to build forests. Use
dtype=np.float32
for maximum efficiency.- yIgnored
Not used, present for API consistency by convention.
- sample_weightarray-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:
- X_transformedsparse matrix of shape (n_samples, n_out)
Transformed dataset.
- get_feature_names_out(input_features=None)[source]¶
Get output feature names for transformation.
- Parameters:
- input_featuresarray-like of str or None, default=None
Only used to validate feature names with the names seen in
fit
.
- Returns:
- feature_names_outndarray of str objects
Transformed feature names, in the format of
randomtreesembedding_{tree}_{leaf}
, wheretree
is the tree used to generate the leaf andleaf
is the index of a leaf node in that tree. Note that the node indexing scheme is used to index both nodes with children (split nodes) and leaf nodes. Only the latter can be present as output features. As a consequence, there are missing indices in the output feature names.
- get_params(deep=True)[source]¶
Get parameters for this estimator.
- Parameters:
- deepbool, default=True
If True, will return the parameters for this estimator and contained subobjects that are estimators.
- Returns:
- paramsdict
Parameter names mapped to their values.
- property n_features_¶
DEPRECATED: Attribute
n_features_
was deprecated in version 1.0 and will be removed in 1.2. Usen_features_in_
instead.Number of features when fitting the estimator.
- set_params(**params)[source]¶
Set the parameters of this estimator.
The method works on simple estimators as well as on nested objects (such as
Pipeline
). The latter have parameters of the form<component>__<parameter>
so that it’s possible to update each component of a nested object.- Parameters:
- **paramsdict
Estimator parameters.
- Returns:
- selfestimator instance
Estimator instance.
- transform(X)[source]¶
Transform dataset.
- Parameters:
- X{array-like, sparse matrix} of shape (n_samples, n_features)
Input data to be transformed. Use
dtype=np.float32
for maximum efficiency. Sparse matrices are also supported, use sparsecsr_matrix
for maximum efficiency.
- Returns:
- X_transformedsparse matrix of shape (n_samples, n_out)
Transformed dataset.
Examples using sklearn.ensemble.RandomTreesEmbedding
¶
Feature transformations with ensembles of trees
Hashing feature transformation using Totally Random Trees
Manifold learning on handwritten digits: Locally Linear Embedding, Isomap…