Linq query to get the distinct values in a list

Question

Suppose this is my member class

class Member 
{
    public string CategoryId { get; set; }
    public string MemberName { get; set; }
    public int Distance { get; set; }
}

And, this is list.

var list = new List<Member>();
list.Add(new { CategoryId = "01", MemberName="andy" Distance=3});
list.Add(new { CategoryId = "02", MemberName="john" Distance=5});
list.Add(new { CategoryId = "01", MemberName="mathew" Distance=7});
list.Add(new { CategoryId = "03", MemberName="bakara" Distance=2});

Can anyone please suggest the logic/ linq query to get the List having distinct/unique categoryID with Shortest distance.

The output should be :

list.Add(new { CategoryId = "01", MemberName="andy" Distance=3});
list.Add(new { CategoryId = "02", MemberName="john" Distance=5});
list.Add(new { CategoryId = "03", MemberName="bakara" Distance=2});

Answer 1

Group the list into categories, then order each grouping by distance, taking the first item (the lowest distance). Project the results into a new Member collection.

var query = from member in list 
            group member by member.CategoryId into memberGrouping
            let groupedMember = memberGrouping.OrderBy (mg => mg.Distance).First() 
            select new Member()
            { 
              CategoryId = memberGrouping.Key, 
              MemberName = groupedMember.MemberName, 
              Distance = groupedMember.Distance 
            };