AI engineering glossary · Feature engineering data prep
What is unknown category handling?
Unknown category handling: The policy for categories seen at prediction time but absent from training data. Common options are ignoring them (all-zero one-hot row), mapping them to an 'unknown' bucket or raising an error. Without a plan, production pipelines crash or misbehave.
Unknown category handling: an example
A model trained before a new city launched sees 'Kochi' in production; with handle_unknown set to ignore, the one-hot row is simply all zeros.
Related terms
More Feature engineering data prep terms
- Variance threshold
- Weight of evidence
- Window feature
- Winsorization
- Wrapper method
- Yeo-Johnson transform
- ADASYN
- Aggregation feature
Where you learn it
Unknown category handling is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.