How to iterate through unique ids

Question

I have a table like this

Id | Similarity
--‐-------------
1  | 40.68880
1  | 40.0090
1  | 38.6799
1  | 5.6789
1  | 5.2347
2  | 69.5680
2  | 34.6700
2  | 19.0007
2