# grouped(by:transform:) Creates a grouping of rows that the method selects by choosing unique values the transform closure creates with elements of a column you select by name. ``` func grouped(by columnName: String, transform: (InputKey?) -> GroupingKey?) -> RowGrouping where GroupingKey : Hashable ``` ## Parameters `columnName` The name of a column. `transform` A closure that transforms a column’s elements into a hashable type. ## Return Value A collection of groups. ## Discussion Create groupings that group rows by: - Telephone area codes - The first letter of a person’s last name - A date’s year or quarter - Number ranges --- 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)