Create Dictionary(of Dictionary) using Grouping in Linq

Question

I know I could do this with loops (as a matter of fact, I currently am, but I am trying to learn / imporve my Linq skills and i also hope it will provide a more efficent sol

Answer 1

This more or less Spender's solution, but this works.

In C#

var dict = lstTeachers.Zip(lstStudentsSex, (teacher, sex) => new { teacher, sex })
    .Zip(lstStudentName, (x, student) => new { x.teacher, x.sex, student })
    .GroupBy(x => x.teacher)
    .ToDictionary(g => g.Key, g => g.GroupBy(x => x.sex)
        .ToDictionary(p => p.Key, p => p.Select(x => x.student)));