---
title: "grouped(by:)"
framework: tabulardata
role: symbol
role_heading: Instance Method
path: "tabulardata/dataframeprotocol/grouped(by:)-77mq2"
---

# grouped(by:)

Creates a grouping of rows that the method selects by choosing unique values in a column.

## Declaration

```swift
func grouped<GroupingKey>(by columnID: ColumnID<GroupingKey>) -> RowGrouping<GroupingKey> where GroupingKey : Hashable
```

## Parameters

- `columnID`: A column identifier.

## Return Value

Return Value A collection of groups.

## See Also

### Creating a Row Grouping by a Column

- [grouped(by:timeUnit:)](tabulardata/dataframeprotocol/grouped(by:timeunit:)-7s782.md)
- [grouped(by:timeUnit:)](tabulardata/dataframeprotocol/grouped(by:timeunit:)-78cy.md)
- [grouped(by:transform:)](tabulardata/dataframeprotocol/grouped(by:transform:)-3cr4p.md)
- [grouped(by:transform:)](tabulardata/dataframeprotocol/grouped(by:transform:)-3aade.md)