Removing unwanted records from a data set can be accomplished by using a ________ operator in RapidMiner.

• A. Map
• B. Sort
• C. Aggregate
• D. Filter

Answer: (D)

Filtering data to remove unwanted records is a common data cleaning step. In RapidMiner, the Filter operator lets you specify a criterion and then keeps only the rows that satisfy it (or, alternatively, drops those that do). This is exactly what removing unwanted records entails: you define what you want to keep and discard the rest. For example, you can filter to keep only rows where a value exceeds a threshold, or where a feature is not missing. Other operators do not remove rows: Map changes attribute values, Sort only reorders examples, and Aggregate summarizes or groups data. So using Filter is the appropriate choice to remove unwanted records.