I knew the general idea immediately but fumbled the month-to-quarter mapping under pressure.
Start by clarifying the data format and edge cases, then demonstrate both SQL and Python solutions. In SQL, use integer arithmetic to extract year and quarter; in Python, parse the integer as a string or use datetime. Finally, discuss performance and scalability considerations.
Pro tip: Mention that you would validate the conversion with a few sample rows and consider using vectorized operations in Python for large datasets, as Point72 deals with high-frequency data.
Confirm the format (YYYYMMDD) and ask about invalid dates, nulls, or out-of-range values. Discuss how to handle them (e.g., filter or flag).
Extract year as date_int / 10000 and month as (date_int % 10000) / 100, then compute quarter as (month - 1) / 3 + 1. Concatenate to form 'YYYY_QX'.
Convert integer to string, slice year and month, compute quarter, and format. Alternatively, use pandas.to_datetime with format='%Y%m%d' and then extract quarter.
In SQL, avoid functions on columns if possible; in Python, use vectorized operations (e.g., pandas) instead of row-wise apply. Mention that integer arithmetic is faster than string parsing.
Test with edge cases like January (Q1), December (Q4), and invalid dates. Show sample output to confirm correctness.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.