LINQ: Distinct values

Question

I have the following item set from an XML:

id           category

5            1
5            3
5            4
5            3
5            3

<

Answer 1

Since we are talking about having every element exactly once, a "set" makes more sense to me.

Example with classes and IEqualityComparer implemented:

 public class Product
    {
        public int Id { get; set; }
        public string Name { get; set; }

        public Product(int x, string y)
        {
            Id = x;
            Name = y;
        }
    }

    public class ProductCompare : IEqualityComparer
    {
        public bool Equals(Product x, Product y)
        {  //Check whether the compared objects reference the same data.
            if (Object.ReferenceEquals(x, y)) return true;

            //Check whether any of the compared objects is null.
            if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))
                return false;

            //Check whether the products' properties are equal.
            return x.Id == y.Id && x.Name == y.Name;
        }
        public int GetHashCode(Product product)
        {
            //Check whether the object is null
            if (Object.ReferenceEquals(product, null)) return 0;

            //Get hash code for the Name field if it is not null.
            int hashProductName = product.Name == null ? 0 : product.Name.GetHashCode();

            //Get hash code for the Code field.
            int hashProductCode = product.Id.GetHashCode();

            //Calculate the hash code for the product.
            return hashProductName ^ hashProductCode;
        }
    }

Now

List originalList = new List {new Product(1, "ad"), new Product(1, "ad")};
var setList = new HashSet(originalList, new ProductCompare()).ToList();

setList will have unique elements

I thought of this while dealing with .Except() which returns a set-difference