create a new column core interview pattern Pattern
1 problems
Pattern pages help build reusable solving frames. Identify signals first, then explain state, transition, and edge handling.
Recognition Signals
- The candidate uses direct assignment to create the new column.
- The candidate understands DataFrame manipulation with methods like `assign()` or `apply()`.
Solve Flow
- 1. Define the active state/window.
- 2. Update state while preserving invariants.
- 3. Validate with edge-heavy examples.
Common Misses
- Incorrectly assigning the new column without ensuring it calculates the correct value.