# 4. Unsupervised Metric Learning¶

Unsupervised metric learning algorithms only take as input an (unlabeled) dataset X. For now, in metric-learn, there only is Covariance, which is a simple baseline algorithm (see below).

## 4.1. Algorithms¶

### 4.1.1. Covariance¶

Covariance does not “learn” anything, rather it calculates the covariance matrix of the input data. This is a simple baseline method. It can be used for ZCA whitening of the data (see the Wikipedia page of whitening transformation).

from metric_learn import Covariance