Flag rows in Python (pandas)

When to use it

Unusual but possibly legitimate values that need human review.

How

A boolean Series assigned to a new column.

df["needs_review"] = df["amount"] > Decimal("5000.00")

• Convert to bool explicitly if the comparison can produce <NA>.

Pitfalls

• Deleting or capping instead of flagging.
• Getting the boundary wrong (> versus >=).