Rx operator to distinct sequences

Question

IMPORTANT: for a description of the results and some more details, please have a look also to my answer

I need to group and filter a sequence of objects

Answer 1

I'm not sure if this does exactly what you'd like, but you may be to group the elements explicitly using the group keyword, and then to manipulate the various IObservables separately before recombining them.

E.g. if we have class definitions such as

class A
{
    public char Key { get; set; }
}

class X : A { }
...

and a Subject

Subject subject = new Subject();

then we can write

var buffered =
    from a in subject
    group a by new { Type = a.GetType(), Key = a.Key } into g
    from buffer in g.Buffer(TimeSpan.FromMilliseconds(300))
    where buffer.Any()
    select new
    {
        Count = buffer.Count,
        Type = buffer.First().GetType().Name,
        Key = buffer.First().Key
    };

buffered.Do(Console.WriteLine).Subscribe();

We can test this with the data you provided:

subject.OnNext(new X { Key = 'a' }); 
Thread.Sleep(100);
subject.OnNext(new X { Key = 'b' }); 
Thread.Sleep(100);
subject.OnNext(new X { Key = 'a' }); 
Thread.Sleep(100);
...
subject.OnCompleted();

To get the output you provided:

{ Count = 2, Type = X, Key = a }
{ Count = 1, Type = X, Key = b }
{ Count = 1, Type = Y, Key = b }
{ Count = 1, Type = Y, Key = c }
{ Count = 2, Type = Z, Key = a }
{ Count = 2, Type = Z, Key = c }
{ Count = 1, Type = Z, Key = b }