Reference · Python (pandas)
Map values with a dictionary in Python (pandas)
Replace each spelling with its approved value using a reviewed dictionary, and decide what happens to unmapped values.
When to use it
Categories with many spellings for one meaning.
How
Series.map with a function that returns None for unknown values.
s.map(lambda v: DICTIONARY.get(v) if isinstance(v, str) else None)
- Series.map(dict) also returns missing for unmapped keys; Series.replace keeps them unchanged.
Pitfalls
- Keeping unmapped values unchanged.
- Mapping before normalizing.
- Guessing mappings for unseen spellings.
Lesson: Map categories with an approved dictionary
Practise it: Map channels with an approved dictionary