Nearest centroid classifier.
Each class is represented by its centroid, with test samples classified to the class with the nearest centroid.
Read more in the :ref:`User Guide <nearest_centroid_classifier>`.
Parameters ---------- metric : str or callable The metric to use when calculating distance between instances in a feature array. If metric is a string or callable, it must be one of the options allowed by metrics.pairwise.pairwise_distances for its metric parameter. The centroids for the samples corresponding to each class is the point from which the sum of the distances (according to the metric) of all samples that belong to that particular class are minimized. If the 'manhattan' metric is provided, this centroid is the median and for all other metrics, the centroid is now set to be the mean.
.. versionchanged:: 0.19 ``metric='precomputed'`` was deprecated and now raises an error
shrink_threshold : float, default=None Threshold for shrinking centroids to remove features.
Attributes ---------- centroids_ : array-like of shape (n_classes, n_features) Centroid of each class.
classes_ : array of shape (n_classes,) The unique classes labels.
Examples -------- >>> from sklearn.neighbors import NearestCentroid >>> import numpy as np >>> X = np.array([-1, -1], [-2, -1], [-3, -2], [1, 1], [2, 1], [3, 2]
) >>> y = np.array(1, 1, 1, 2, 2, 2
) >>> clf = NearestCentroid() >>> clf.fit(X, y) NearestCentroid() >>> print(clf.predict([-0.8, -1]
)) 1
See also -------- sklearn.neighbors.KNeighborsClassifier: nearest neighbors classifier
Notes ----- When used for text classification with tf-idf vectors, this classifier is also known as the Rocchio classifier.
References ---------- Tibshirani, R., Hastie, T., Narasimhan, B., & Chu, G. (2002). Diagnosis of multiple cancer types by shrunken centroids of gene expression. Proceedings of the National Academy of Sciences of the United States of America, 99(10), 6567-6572. The National Academy of Sciences.