NaN Is Weird
5 days ago
- #Python
- #Oddities
- #Programming
- float('nan') is hashable and can be added to sets and dictionaries.
- A set with multiple float('nan') entries will show duplicates because nan != nan.
- float('nan') does not equal itself, but 'is' comparison returns True for the same instance.
- Using float('nan') as a dictionary key is possible, but retrieving values requires the exact nan instance.
- Counting occurrences of float('nan') in an iterable with Counter does not work as expected.
- This behavior is a Python oddity, unlikely to be used deliberately in practice.