C# - Check DataTable form same field

Question

I would like to check the same field in Datatable, and I want to setup a number for each row which starts from Zero, if same field found, number + 1

Original Table

Name
==========
John
John
John
Tommy
Tommy
Andy

How to setup number like :

Name  | Number
=================
John  |   0
John  |   1
John  |   2
Tommy |   0
Tommy |   1
Andy  |   0

Any ideas for this? Thanks for your help.

Answer 1

Try this:

var Rank = datatable1.GroupBy(x => x.Name)
.Select(g => new {g, count= g.Count()})
.SelectMany(t => t.g.Select(b => b)
.Zip(Enumerable.Range(1,t.count), (j,i) => new {j.Name, rn = i}));

foreach (var i in Rank)
{
    Console.WriteLine("{0} {1}",i.Name, i.rn);
}

Output:

John  |   1
John  |   2
John  |   3
Tommy |   1
Tommy |   2
Andy  |   1