Remove duplicates with a survivor rule in Python (pandas)

When to use it

Repeated records at the table's grain: re-sent rows, versions, the same customer from several systems.

How

Sort by the survivor rule with a stable sort, then Series.duplicated on the key.

df = df.sort_values(["version"], ascending=False, kind="mergesort")
loser = df.duplicated(["order_id", "line_id"])

• duplicated keeps the first occurrence in the current order.

Pitfalls

• Deduplicating at the wrong grain.
• An incomplete order that leaves ties to chance.
• Comparing numbers or timestamps as text.