C# LINQ Ignoring empty values in datatable

I have a datatable that I have grouped as follows:

var result = from data in view.AsEnu开发者_如何学Pythonmerable()
                     group data by new {Group = data.Field<string>("group_no")}
                     into grp
                     select new
                     {
                         Group = grp.Key.Group,
                         PRAS = grp.Average(c => Convert.ToDouble(c.Field<string>("pAKT Total")))

                     };

Now, the average function is also counting the empty cells in it's calculation. For example, there are 10 cells with only 5 populated with values. I want the average to be the sum of the 5 values divided by 5.

How can I ensure that it does what I want?

Thanks.

Maybe something like this:

PRAS = grp.Select(row => row.Field<string>("pAKT Total"))
          .Where(s => !String.IsNullOrEmpty(s))
          .Select(Convert.ToDouble)
          .Average()

To my knowledge, that's not possible with the Average method.
You can however achieve the result you want to, with the following substitute:

PRAS = grp.Sum(c => Convert.ToDouble(c.Field<string>("pAKT Total"))) / grp.Count(c => !c.IsDBNull)

This only makes sense, when you want to select the "empty" rows in the group, but just don't want to include them in your average. If you don't need the "empty" rows at all, don't select them in the first place, i.e. add a where clause that excludes them.