AI engineering glossary · Feature engineering data prep
What is rare category grouping?
Rare category grouping: Merging infrequent category values into a single 'Other' bucket before encoding. It reduces column count, stops the model overfitting to tiny groups and prepares for unseen categories at prediction time.
Rare category grouping: an example
Of 300 car brands in a dataset, all brands with under 50 rows are relabelled 'Other', leaving about 20 distinct values.
Related terms
More Feature engineering data prep terms
- Ratio feature
- Recursive feature elimination
- Robust scaling
- Rolling statistics
- Sample weights
- SMOTE
- Standardization
- Stemming
Where you learn it
Rare category grouping is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.