- [ ] [6.5.1. PCA: principal component analysis](https://scikit-learn.org/stable/modules/unsupervised_reduction.html#pca-principal-component-analysis) - [ ] [6.5.2. Random projections](https://scikit-learn.org/stable/modules/unsupervised_reduction.html#random-projections) - [ ] [6.5.3. Feature agglomeration](https://scikit-learn.org/stable/modules/unsupervised_reduction.html#feature-agglomeration)
