可观察序列Rx c＃的多个订阅

Question

I am trying to learn Rx framework in .NET and in the process of applying it one of the tasks that I am working on. The functionality that I am trying is explained in this simple use case below.

I have a sequence of IEnumerable which I need to process in parallel and apply a function( async function ) to it which returns an int. based on the value returned. In the code below the new sequences oddSequence and evenSequence are created only after the original "sequence" is created, so there is not real "fire and forget" happening here. What is correct way to approach this problem using Rx?

    public void TestRx()
    {
        IEnumerable<string> inputs = new string[] { "T-1", "T-2", "T-3"};

        var sequence = inputs.ToObservable().Select(x => ReturnResult(x)).Merge();

        var oddSequence = sequence.Where(x => (x%2) != 0);
        var evenSequence = sequence.Where(x => (x%2) == 0);

        oddSequence.Subscribe(i => Console.WriteLine($"ODD VALUE {i}"));
        evenSequence.Subscribe(i => Console.WriteLine($"EVEN VALUE {i}"));
    }

    public async Task<int> ReturnResult(string s)
    {
        int result = -1;
        Int32.TryParse(s.Split('-')[1], out result);
        return result;
    }

Thank you helping me out

Answer 1

This will do the job:

private Random random = new Random();

public void TextRx()
{
    new[] {"T-1", "T-2", "T-3"}
        .Select(s => ReturnResult(s).ToObservable())
        .Merge()
        .GroupBy(i => i % 2 == 0)
        .SelectMany(g => g.Select(i => (g.Key, Value: i)))
        .Subscribe(o => Console.WriteLine($"{(o.Key ? "EVEN" : "ODD")} VALUE {o.Value}"));
}

public async Task<int> ReturnResult(string s)
{
    await Task.Delay(random.Next(5000));
    int.TryParse(s.Split('-')[1], out var result);
    return result;
}

• It uses ValueTuple , which is a C# 7 feature. You'd need to grab it with Nuget. Of course you could use an anonymous object, but I prefer ValueTuple . It's also using out variables from C#7 and string interpolation from C# 6.