- [ ] [6.3.1. Standardization, or mean removal and variance scaling](https://scikit-learn.org/stable/modules/preprocessing.html#standardization-or-mean-removal-and-variance-scaling) - [ ] [6.3.2. Non-linear transformation](https://scikit-learn.org/stable/modules/preprocessing.html#non-linear-transformation) - [ ] [6.3.3. Normalization](https://scikit-learn.org/stable/modules/preprocessing.html#normalization) - [ ] [6.3.4. Encoding categorical features](https://scikit-learn.org/stable/modules/preprocessing.html#encoding-categorical-features) - [ ] [6.3.5. Discretization](https://scikit-learn.org/stable/modules/preprocessing.html#discretization) - [ ] [6.3.6. Imputation of missing values](https://scikit-learn.org/stable/modules/preprocessing.html#imputation-of-missing-values) - [ ] [6.3.7. Generating polynomial features](https://scikit-learn.org/stable/modules/preprocessing.html#generating-polynomial-features) - [ ] [6.3.8. Custom transformers](https://scikit-learn.org/stable/modules/preprocessing.html#custom-transformers)