# filter(on:_:) Returns a selection of rows that satisfy a predicate in the columns you select by column identifier. ``` func filter(on columnID: ColumnID, _ isIncluded: (T?) throws -> Bool) rethrows -> DataFrame.Slice ``` ## Parameters `columnID` The identifier of a column in the slice. `isIncluded` A predicate closure that receives an element of the column as its argument, and returns a Boolean that indicates whether the slice includes the element’s row. ## Return Value A data frame slice that contains the rows that satisfy the predicate. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)