Is there an easier way to use Rx's GroupBy operator?

Question

I'm just playing with the concept of GroupBy inside Rx. So, I wondered how hard it would be to write a console application that continuously reads lines, groups them by similar words and just prints out the word among the current count of how often the word was written before. It really was a breeze to do that but I wonder if my attempt could be rewritten in a more elegant way. Especially if I can get rid of the nested Subscribes.

Here is what I have:

static void Main(string[] args)
{
    var subject = new Subject<string>();

    var my = subject.GroupBy(x => x);

    my.Subscribe(x => x.Scan(new { Chars = string.Empty, Count = 0},
                                 (a, chars) => new { Chars = chars, Count = a.Count + 1})
      .Subscribe(result => Console.WriteLine("You typed {0} {1} times", result.Chars, 
                 result.Count)));

    while (true)
    {
        subject.OnNext(Console.ReadLine());
    }
}

---

Result

test
you typed test 1 times
test
you typed test 2 times
hallo
you typed test 1 times
test
you typed test 3 times
...

Answer 1

Ok, this looks a lot better! Can anyone even do better than that?

    static void Main(string[] args)
    {
        var subject = new Subject<string>();

        subject
            .GroupBy(x => x)
            .SelectMany(x => x.Scan(new { Chars = string.Empty, Count = 0},(a, chars) => new { Chars = chars, Count = a.Count + 1}))
            .Subscribe(result => Console.WriteLine("You typed {0} {1} times", result.Chars, result.Count));

        while (true)
        {
            subject.OnNext(Console.ReadLine());
        }
    }

Answer 2

Ok, here is another one! I think this one is easier to read since we don't depend on the Scan method to carry the string through the computation:

    static void Main(string[] args)
    {
        var subject = new Subject<string>();

        subject
          .GroupBy(x => x)
          .SelectMany(x => x.Scan(0, (count, _) => ++count).Zip(x, (count, chars) => new { Chars = chars, Count = count}))
          .Subscribe(result => Console.WriteLine("You typed {0} {1} times", result.Chars, result.Count));

        while (true)
        {
            subject.OnNext(Console.ReadLine());
        }
    }

Can anyone do even better?

Answer 3

This looks a lot cleaner to me. Should also showcase how much more helpful it is when you give more descriptive names to your variables.

static void Main(string[] args)
{
    var lineReader = new Subject<string>();

    lineReader.GroupBy(line => line)
        .Subscribe(lineGroup =>
        {
            lineGroup.Scan(0, (acc, _) => ++acc)
                .Subscribe(count =>
                {
                    var line = lineGroup.Key;
                    var timeSuffix = count == 1 ? "" : "s";
                    Console.WriteLine("You typed {0} {1} time{2}.", line, count, timeSuffix);
                });
        });

    String readLine;
    while ((readLine = Console.ReadLine()) != null)
        lineReader.OnNext(readLine);
}