+-----+-----+----+------------+------------+
|   a |   b |  i |          x |          y |
+-----+-----+----+------------+------------+
| pan | pan |  1 | 0.34679014 | 0.72680286 |
| eks | pan |  2 | 0.75867996 | 0.52215111 |
| wye | wye |  3 | 0.20460331 | 0.33831853 |
| eks | wye |  4 | 0.38139939 | 0.13418874 |
| wye | pan |  5 | 0.57328892 | 0.86362447 |
| zee | pan |  6 | 0.52712616 | 0.49322129 |
| eks | zee |  7 | 0.61178406 | 0.18788492 |
| zee | wye |  8 | 0.59855401 | 0.97618139 |
| hat | wye |  9 | 0.03144188 | 0.74955076 |
| pan | wye | 10 | 0.50262601 | 0.95261836 |
+-----+-----+----+------------+------------+
