76 lines
2.3 KiB
Python
76 lines
2.3 KiB
Python
"""
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Feature agglomeration. Base classes and functions for performing feature
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agglomeration.
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"""
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# Author: V. Michel, A. Gramfort
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# License: BSD 3 clause
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import numpy as np
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from ..base import TransformerMixin
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from ..utils.validation import check_is_fitted
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from scipy.sparse import issparse
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###############################################################################
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# Mixin class for feature agglomeration.
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class AgglomerationTransform(TransformerMixin):
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"""
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A class for feature agglomeration via the transform interface.
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"""
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def transform(self, X):
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"""
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Transform a new matrix using the built clustering.
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Parameters
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----------
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X : array-like of shape (n_samples, n_features) or \
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(n_samples, n_samples)
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A M by N array of M observations in N dimensions or a length
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M array of M one-dimensional observations.
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Returns
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-------
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Y : ndarray of shape (n_samples, n_clusters) or (n_clusters,)
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The pooled values for each feature cluster.
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"""
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check_is_fitted(self)
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X = self._validate_data(X, reset=False)
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if self.pooling_func == np.mean and not issparse(X):
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size = np.bincount(self.labels_)
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n_samples = X.shape[0]
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# a fast way to compute the mean of grouped features
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nX = np.array(
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[np.bincount(self.labels_, X[i, :]) / size for i in range(n_samples)]
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)
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else:
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nX = [
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self.pooling_func(X[:, self.labels_ == l], axis=1)
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for l in np.unique(self.labels_)
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]
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nX = np.array(nX).T
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return nX
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def inverse_transform(self, Xred):
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"""
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Inverse the transformation and return a vector of size `n_features`.
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Parameters
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----------
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Xred : array-like of shape (n_samples, n_clusters) or (n_clusters,)
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The values to be assigned to each cluster of samples.
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Returns
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-------
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X : ndarray of shape (n_samples, n_features) or (n_features,)
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A vector of size `n_samples` with the values of `Xred` assigned to
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each of the cluster of samples.
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"""
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check_is_fitted(self)
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unil, inverse = np.unique(self.labels_, return_inverse=True)
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return Xred[..., inverse]
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