# Group / ungroup / flatten columns

> For the complete documentation index, see [llms.txt](https://kotlin.github.io/dataframe/llms.txt).

* [group](group.html) — groups given columns into [ColumnGroups](datacolumn.html#columngroup).

* [ungroup](ungroup.html) — ungroups given [ColumnGroups](datacolumn.html#columngroup) by replacing them with their children columns

* [flatten](flatten.html) — recursively removes all column groupings under given [ColumnGroups](datacolumn.html#columngroup), leaving only [ValueColumns](datacolumn.html#valuecolumn) and [FrameColumns](datacolumn.html#framecolumn)

These operations are special cases of general [move](move.html) operation.