Hi I'm having issues with filtering the data

Developers Language Support
1

I’ve

public type Posts = {
    author : Text;
    title : Text;
    content : Text;
    category : Text;
    categoryId : Nat;
    likes : Nat;
    published : Bool;

  };

var map1 = HashMap.HashMap<Principal, List.List<Posts>>(1, Principal.equal, Principal.hash);
var map2 = HashMap.HashMap<categoryId, List.List<Principal>>(1, Nat.equal, Hash.hash);

public shared (msg) func fetchPosts(categoryId : Nat) : async [Posts] {
    var users : List.List<Principal> = switch (map2.get(categoryId)) {
      case null List.nil<Principal>();
      case (?result) result;
    };

    for (x in Iter.fromList(users)) {
 
    };
}

If user selects a category i want to get all the posts unique to that category by using categoryId

I want to filter the posts by likes in descending specific to the category how can i do it?