Pivot data using LINQ

Marc's answer gives sparse matrix that can't be pumped into Grid directly.
I tried to expand the code from the link provided by Vasu as below:

public static Dictionary<TKey1, Dictionary<TKey2, TValue>> Pivot3<TSource, TKey1, TKey2, TValue>(
    this IEnumerable<TSource> source
    , Func<TSource, TKey1> key1Selector
    , Func<TSource, TKey2> key2Selector
    , Func<IEnumerable<TSource>, TValue> aggregate)
{
    return source.GroupBy(key1Selector).Select(
        x => new
        {
            X = x.Key,
            Y = source.GroupBy(key2Selector).Select(
                z => new
                {
                    Z = z.Key,
                    V = aggregate(from item in source
                                  where key1Selector(item).Equals(x.Key)
                                  && key2Selector(item).Equals(z.Key)
                                  select item
                    )

                }
            ).ToDictionary(e => e.Z, o => o.V)
        }
    ).ToDictionary(e => e.X, o => o.Y);
} 
internal class Employee
{
    public string Name { get; set; }
    public string Department { get; set; }
    public string Function { get; set; }
    public decimal Salary { get; set; }
}
public void TestLinqExtenions()
{
    var l = new List<Employee>() {
    new Employee() { Name = "Fons", Department = "R&D", Function = "Trainer", Salary = 2000 },
    new Employee() { Name = "Jim", Department = "R&D", Function = "Trainer", Salary = 3000 },
    new Employee() { Name = "Ellen", Department = "Dev", Function = "Developer", Salary = 4000 },
    new Employee() { Name = "Mike", Department = "Dev", Function = "Consultant", Salary = 5000 },
    new Employee() { Name = "Jack", Department = "R&D", Function = "Developer", Salary = 6000 },
    new Employee() { Name = "Demy", Department = "Dev", Function = "Consultant", Salary = 2000 }};

    var result5 = l.Pivot3(emp => emp.Department, emp2 => emp2.Function, lst => lst.Sum(emp => emp.Salary));
    var result6 = l.Pivot3(emp => emp.Function, emp2 => emp2.Department, lst => lst.Count());
}

* can't say anything about the performance though.


I'm not saying it is a great way to pivot - but it is a pivot...

    // sample data
    var data = new[] {
        new { Foo = 1, Bar = "Don Smith"},
        new { Foo = 1, Bar = "Mike Jones"},
        new { Foo = 1, Bar = "James Ray"},
        new { Foo = 2, Bar = "Tom Rizzo"},
        new { Foo = 2, Bar = "Alex Homes"},
        new { Foo = 3, Bar = "Andy Bates"},
    };
    // group into columns, and select the rows per column
    var grps = from d in data
              group d by d.Foo
              into grp
              select new {
                  Foo = grp.Key,
                  Bars = grp.Select(d2 => d2.Bar).ToArray()
              };

    // find the total number of (data) rows
    int rows = grps.Max(grp => grp.Bars.Length);

    // output columns
    foreach (var grp in grps) {
        Console.Write(grp.Foo + "\t");
    }
    Console.WriteLine();
    // output data
    for (int i = 0; i < rows; i++) {
        foreach (var grp in grps) {
            Console.Write((i < grp.Bars.Length ? grp.Bars[i] : null) + "\t");
        }
        Console.WriteLine();
    }