Linq列表的平均值及其所有嵌套列表值

Question

I have a List<A> . Each A has a List<B> where B has an int x . I am trying to calculate the average value of x for all A .

I have tried:

@Model.AList.ForEach(a => a.BList.Average(b => b.x))

This complains about missing a return value. I've experimented with something like:

@Model.Alist.ForEach(a =>
{
    return a.Blist.Average(b => b.x);
})

But this is incorrect syntax since ForEach expects void return.

How can I calculate the average value of x for all A usin a LINQ query?

Answer 1

First flatten the collection, then take the average. Something like this:

@Model.AList.SelectMany(a => a.BList).Average(b => b.x)

Answer 2

我不确定您是否要为每个BList均设置不同的平均值，所以这是解决方案：

@Model.AList.Select(a => a.BList.Average(b => b.x))