df.groupBy { city }.count()

Input DataFrame: rowsCount = 7, columnsCount = 5

Step 1: GroupBy

Output DataFrame: rowsCount = 6, columnsCount = 2

df.pivot { city }.count { age > 18 }

Input DataFrame: rowsCount = 7, columnsCount = 5

Step 1: Pivot

Output DataRow

df.pivot { name.firstName }.groupBy { name.lastName }.count()

Input DataFrame: rowsCount = 7, columnsCount = 5

Step 1: Pivot

Step 2: PivotGroupBy

Output DataFrame: rowsCount = 7, columnsCount = 2