如何使用linq对网格中的列中的所有单元格求和

Question

I have a requirement. like....

Sname Marks Percentage

aa    50     50
aa    60     60
bb    80     80
bb    60     60

here i want to add marks and display percentage like below

Sname Marks Percentage
aa    50     50
aa    60     60
-----------------
aa    110    55
----------------
bb    80     80
bb    60     60
-----------------
bb    140    70
-----------------

It should be done using the linq query I am using the follwing linq query which performs grouping for display.

List<Studentsmarkslist> mrksbrpby = (from n in lstmrks
     group n by new { n.StudentName,n.Total,n.Percentage }  
        into g  orderby g.Key.StudentName
     select new Studentsmarkslist
     {
         StudentName = g.Key.StudentName,
         Total = g.Key.Total,
         Percentage = g.Key.Percentage

    }).ToList();
return mrksbrpby

Please suggest me how to perform sum and percentage as mentioned above way using this linq query

Answer 1

you want to use the .Sum() method for summing all the Marks values, and .Average() for getting the average percentage.

Examples of usage can be found by following the MSDN links:

.Sum() read more here: http://msdn.microsoft.com/en-us/library/bb338442.aspx

.Average() read more here: http://msdn.microsoft.com/en-us/library/bb338413.aspx

Answer 2

You can group the list of entries by the students' name. Then iterate through each group to display:

• Individual entry belong to the student
• Aggregated result by LINQ's Sum() and Average()

Like this:

var groups = from n in lstmrks
             group n by n.StudentName;
foreach (var g in groups)
{
    foreach (var s in g)
        Console.WriteLine("{0}\t{1}\t{2}", s.StudentName, s.Total, s.Percentage);
    Console.WriteLine("-----------------");
    Console.WriteLine("{0}\t{1}\t{2}", g.Key, g.Sum(x => x.Total), g.Average(x => x.Percentage));
    Console.WriteLine("-----------------");
}