Closed
Description
Describe the bug
NearestCentroid class throw a FutureWarning when using metric='cosine'.
Actually, the metric is use for two things:
- inside
.fit()for the computation of the centroids:- with euclidean: centroids are computed using the mean of features
- with manhattan: centroids are computed using the median
if self.metric == "manhattan":
# NumPy does not calculate median of sparse matrices.
if not is_X_sparse:
self.centroids_[cur_class] = np.median(X[center_mask], axis=0)
else:
self.centroids_[cur_class] = csc_median_axis_0(X[center_mask])
else:
# TODO(1.5) remove warning when metric is only manhattan or euclidean
if self.metric != "euclidean":
warnings.warn(
"Averaging for metrics other than "
"euclidean and manhattan not supported. "
"The average is set to be the mean."
)
self.centroids_[cur_class] = X[center_mask].mean(axis=0)- inside
.predict(): the metric is used for the pairwise distance
def predict(self, X):
...
return self.classes_[
pairwise_distances_argmin(X, self.centroids_, metric=self.metric)
]But, what if I want to use centroids computed with the mean of features and using cosine (or other) metric to compute the pairwise distance ?
Steps/Code to Reproduce
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(metric='cosine')
clf.fit(X, y)
print(clf.predict([[-0.8, -1]]))Expected Results
No error is thrown.
Actual Results
../sklearn/neighbors/_nearest_centroid.py:150: FutureWarning: Support for distance metrics other than euclidean and manhattan and for callables was deprecated in version 1.3 and will be removed in version 1.5.
warnings.warn(
../sklearn/neighbors/_nearest_centroid.py:201: UserWarning: Averaging for metrics other than euclidean and manhattan not supported. The average is set to be the mean.
Versions
System:
python: 3.8.3 (default, Jun 16 2021, 12:00:44) [Clang 12.0.5 (clang-1205.0.22.9)]
executable: /Users/yohanntvmbp/.pyenv/versions/tvmealvisionapi/bin/python
machine: macOS-14.0-x86_64-i386-64bit
Python dependencies:
sklearn: 1.3.1
pip: 22.3.1
setuptools: 62.1.0
numpy: 1.21.5
scipy: 1.7.3
Cython: None
pandas: 1.3.5
matplotlib: 3.6.2
joblib: 1.3.2
threadpoolctl: 3.1.0
Built with OpenMP: True