GroupDocs

Groups the specified columns within the DataFrame into column group.

This function does not immediately group the columns but instead selects columns to group and returns a GroupClause, which serves as an intermediate step. The GroupClause allows specifying the final destination of the selected columns using methods such as into and, that return a new DataFrame with grouped columns. Check out Grammar.

This can include column groups and nested columns.

See Selecting Columns.

For more information: See group on the documentation website.

Reverse operation: ungroup.

It is a special case of move operation.

Don't confuse this with groupBy, which groups the dataframe by the values in the selected columns!