Original Data:
[
 [ 1  1  2  2  3]
 [10 15 13 11  6]
]

Groups: [1 2 3]
Transposed Groups:
[
 [1]
 [2]
 [3]
]

Masks:
[
 [1 1 0 0 0]
 [0 0 1 1 0]
 [0 0 0 0 1]
]

Group values:
[
 [10 15  0  0  0]
 [ 0  0 13 11  0]
 [ 0  0  0  0  6]
]

Max of each group: [15 13 6]
Final pdl:
[
 [ 1 15]
 [ 2 13]
 [ 3  6]
]