sklearn.cluster
.FeatureAgglomeration¶

class
sklearn.cluster.
FeatureAgglomeration
(n_clusters=2, *, affinity='euclidean', memory=None, connectivity=None, compute_full_tree='auto', linkage='ward', pooling_func=<function mean>, distance_threshold=None, compute_distances=False)[source]¶ Agglomerate features.
Similar to AgglomerativeClustering, but recursively merges features instead of samples.
Read more in the User Guide.
 Parameters
 n_clustersint, default=2
The number of clusters to find. It must be
None
ifdistance_threshold
is notNone
. affinitystr or callable, default=’euclidean’
Metric used to compute the linkage. Can be “euclidean”, “l1”, “l2”, “manhattan”, “cosine”, or ‘precomputed’. If linkage is “ward”, only “euclidean” is accepted.
 memorystr or object with the joblib.Memory interface, default=None
Used to cache the output of the computation of the tree. By default, no caching is done. If a string is given, it is the path to the caching directory.
 connectivityarraylike or callable, default=None
Connectivity matrix. Defines for each feature the neighboring features following a given structure of the data. This can be a connectivity matrix itself or a callable that transforms the data into a connectivity matrix, such as derived from kneighbors_graph. Default is None, i.e, the hierarchical clustering algorithm is unstructured.
 compute_full_tree‘auto’ or bool, default=’auto’
Stop early the construction of the tree at n_clusters. This is useful to decrease computation time if the number of clusters is not small compared to the number of features. This option is useful only when specifying a connectivity matrix. Note also that when varying the number of clusters and using caching, it may be advantageous to compute the full tree. It must be
True
ifdistance_threshold
is notNone
. By defaultcompute_full_tree
is “auto”, which is equivalent toTrue
whendistance_threshold
is notNone
or thatn_clusters
is inferior to the maximum between 100 or0.02 * n_samples
. Otherwise, “auto” is equivalent toFalse
. linkage{‘ward’, ‘complete’, ‘average’, ‘single’}, default=’ward’
Which linkage criterion to use. The linkage criterion determines which distance to use between sets of features. The algorithm will merge the pairs of cluster that minimize this criterion.
ward minimizes the variance of the clusters being merged.
average uses the average of the distances of each feature of the two sets.
complete or maximum linkage uses the maximum distances between all features of the two sets.
single uses the minimum of the distances between all observations of the two sets.
 pooling_funccallable, default=np.mean
This combines the values of agglomerated features into a single value, and should accept an array of shape [M, N] and the keyword argument
axis=1
, and reduce it to an array of size [M]. distance_thresholdfloat, default=None
The linkage distance threshold above which, clusters will not be merged. If not
None
,n_clusters
must beNone
andcompute_full_tree
must beTrue
.New in version 0.21.
 compute_distancesbool, default=False
Computes distances between clusters even if
distance_threshold
is not used. This can be used to make dendrogram visualization, but introduces a computational and memory overhead.New in version 0.24.
 Attributes
 n_clusters_int
The number of clusters found by the algorithm. If
distance_threshold=None
, it will be equal to the givenn_clusters
. labels_arraylike of (n_features,)
cluster labels for each feature.
 n_leaves_int
Number of leaves in the hierarchical tree.
 n_connected_components_int
The estimated number of connected components in the graph.
New in version 0.21:
n_connected_components_
was added to replacen_components_
. children_arraylike of shape (n_nodes1, 2)
The children of each nonleaf node. Values less than
n_features
correspond to leaves of the tree which are the original samples. A nodei
greater than or equal ton_features
is a nonleaf node and has childrenchildren_[i  n_features]
. Alternatively at the ith iteration, children[i][0] and children[i][1] are merged to form noden_features + i
 distances_arraylike of shape (n_nodes1,)
Distances between nodes in the corresponding place in
children_
. Only computed ifdistance_threshold
is used orcompute_distances
is set toTrue
.
Examples
>>> import numpy as np >>> from sklearn import datasets, cluster >>> digits = datasets.load_digits() >>> images = digits.images >>> X = np.reshape(images, (len(images), 1)) >>> agglo = cluster.FeatureAgglomeration(n_clusters=32) >>> agglo.fit(X) FeatureAgglomeration(n_clusters=32) >>> X_reduced = agglo.transform(X) >>> X_reduced.shape (1797, 32)
Methods
fit
(X[, y])Fit the hierarchical clustering on the data
fit_transform
(X[, y])Fit to data, then transform it.
get_params
([deep])Get parameters for this estimator.
inverse_transform
(Xred)Inverse the transformation.
set_params
(**params)Set the parameters of this estimator.
transform
(X)Transform a new matrix using the built clustering

fit
(X, y=None, **params)[source]¶ Fit the hierarchical clustering on the data
 Parameters
 Xarraylike of shape (n_samples, n_features)
The data
 yIgnored
 Returns
 self

property
fit_predict
¶ Fit the hierarchical clustering from features or distance matrix, and return cluster labels.
 Parameters
 Xarraylike of shape (n_samples, n_features) or (n_samples, n_samples)
Training instances to cluster, or distances between instances if
affinity='precomputed'
. yIgnored
Not used, present here for API consistency by convention.
 Returns
 labelsndarray of shape (n_samples,)
Cluster labels.

fit_transform
(X, y=None, **fit_params)[source]¶ Fit to data, then transform it.
Fits transformer to X and y with optional parameters fit_params and returns a transformed version of X.
 Parameters
 X{arraylike, sparse matrix, dataframe} of shape (n_samples, n_features)
Input samples.
 yndarray of shape (n_samples,), default=None
Target values (None for unsupervised transformations).
 **fit_paramsdict
Additional fit parameters.
 Returns
 X_newndarray array of shape (n_samples, n_features_new)
Transformed array.

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
 paramsmapping of string to any
Parameter names mapped to their values.

inverse_transform
(Xred)[source]¶ Inverse the transformation. Return a vector of size nb_features with the values of Xred assigned to each group of features
 Parameters
 Xredarraylike of shape (n_samples, n_clusters) or (n_clusters,)
The values to be assigned to each cluster of samples
 Returns
 Xndarray of shape (n_samples, n_features) or (n_features,)
A vector of size n_samples with the values of Xred assigned to each of the cluster of samples.

set_params
(**params)[source]¶ Set the parameters of this estimator.
The method works on simple estimators as well as on nested objects (such as pipelines). 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
 selfobject
Estimator instance.

transform
(X)[source]¶ Transform a new matrix using the built clustering
 Parameters
 Xarraylike of shape (n_samples, n_features) or (n_samples,)
A M by N array of M observations in N dimensions or a length M array of M onedimensional observations.
 Returns
 Yndarray of shape (n_samples, n_clusters) or (n_clusters,)
The pooled values for each feature cluster.