Summarize list by property

Question

I have a list of objects like this:

List list = new List();
list.Add(new ClassName()
{
    Name = 1,
    Amount = 5
});
list.Ad         


        

Answer 1

 var lst = list.GroupBy(g = > g.Name).Select(t = > new
 ClassName()
 {
     Amount = t.Sum(s=>s.Amount), Name = t.Key
 }).ToList();

Answer 2

Do it via LINQ:

var result = list.GroupBy(x => x.Name)
    .Select(x => new ClassName { Name = x.Key, Amount = x.Sum(i => i.Amount) })
    .ToList();

Read more about LINQ here: http://code.msdn.microsoft.com/101-LINQ-Samples-3fb9811b

Answer 3

var result = list.GroupBy(x => x.Name).Select(x => new MyClass() {Name=x.Key, Amount= x.Sum(y => y.Amount));

OR

List<MyClass> result = list.GroupBy(x => x.Name).Select(x => new MyClass() {Name=x.Key, Amount= x.Sum(y => y.Amount)).ToList();