# init(groups:groupKeysColumnName:) Creates a row grouping from a list of groups. ``` init(groups: [(GroupingKey?, D)], groupKeysColumnName: String) where D : DataFrameProtocol ``` ## Parameters `groups` An array of tuples. Each tuple pairs a key with a data frame type. `groupKeysColumnName` The name of the grouping key column the row grouping creates when it generates a data frame, such as its [`ungrouped()`](/documentation/TabularData/RowGrouping/ungrouped()) or [`counts(order:)`](/documentation/TabularData/RowGrouping/counts(order:)) methods. ## Discussion The member data frames must all have the same columns (count, names, and types). --- 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)