NearestNeighbors doesn't work with algorithm="auto" when using mahalanobis distance

When I use NearestNeighbors with mahalanobis distance, I find setting algorithm=‘auto’ (which defaults to ‘ball_tree’) doesn’t seem to work. This throw an error: ValueError: Mahalanobis dist: size of V does not match

import numpy as np from sklearn.datasets import make_classification from sklearn.neighbors import DistanceMetric X, y = make_classification() nn = NearestNeighbors(algorithm='auto', metric='mahalanobis', metric_params={'V': np.cov(X)}) nn.fit(X)

[jnothman]

I suspect it wants covariance between the features, not the samples. I.e. use rowvar=False​

[thomasjpfan]

Thank you @cmarmo for following up on this issue. From https://github.com/scikit-learn/scikit-learn/issues/11807#issuecomment-1302822458, I agree this issue can be closed.