juniorNumPy
What is np.ones in NumPy?
Updated May 17, 2026
Short answer
np.ones creates arrays filled with ones.
Deep explanation
It is commonly used for initializing masks, weights, or identity-like structures in preprocessing.
Real-world example
Feature scaling initialization.
Common mistakes
- Using ones instead of identity matrix when needed.
Follow-up questions
- How is ones different from eye?
- Can ones be used for boolean masks?