对DataTable的DataRow做group

public void DataSetLinq41()
{
    var words4 = testDS.Tables["Words4"].AsEnumerable();
    var wordGroups =
        from w in words4
        group w by w.Field<string>("word")[0] into g
        select new { FirstLetter = g.Key, Words = g };
    foreach (var g in wordGroups)
    {
        Console.WriteLine("Words that start with the letter '{0}':", g.FirstLetter);
        foreach (var w in g.Words)
        {
            Console.WriteLine(w.Field<string>("word"));
        }
    }
    Console.ReadLine();
}


private static DataTable CreateWords4Table()
{
    string[] words = { "blueberry", "chimpanzee", "abacus", "banana", "apple", "cheese" };
    DataTable table = new DataTable("Words4");
    table.Columns.Add("word", typeof(string));

    foreach (string word in words)
    {
        table.Rows.Add(new object[] { word });
    }
    return table;
}

DataSetLinq41();