被动扩展：事件发生的频率

Question

Lets say I have a class like MyClass { string id, string eventType, datetime ts}

ts is the timestamp of the event and Id is on which I want to calculate frequency

I have a hot observable of MyClass , I want to calculate number of events recvd per stringId in the last 30 seconds

If number of events is more than 5 , I raise another event of MyClass (with same Id, and eventType ="New" ) and if it falls down below 3 again , I need to update the previously raised event (with same Id, and eventType ="New" ).

I think I need to use sliding window, I have reached so far

public static IObservable<MyClass> CountFrequency(this IObservable<MyClass> source, TimeSpan withinPeriod, string marker)
{
    // var scheduler = new HistoricalScheduler();
    //  var driveSchedule = source.Subscribe(e => scheduler.AdvanceTo(e.Timestamp)); 
    return source.Window(TimeSpan.FromSeconds(30), TimeSpan.FromSeconds(5))
        .SelectMany(sl => sl)
        .GroupBy(a => a.id)
        .SelectMany(go => go
        .Aggregate(new MyClass(), (acc, evt) => CustomAggFrequency(acc, evt, marker))
        .Select(count => count)));
}

I am not able to understand

a) How to relate scheduler to the timestamp of the data not system time b) How to code the logic of CustomAggFrequency

Any suggestions

Answer 1

Will this not work? Your question is phrased such that it's hard to figure out what you want.

var span = TimeSpan.FromSeconds(30);
var shift = TimeSpan.FromSeconds(5);
var query = source
    .Window(span, shift)
    .Select(window => window
        .GroupBy(item => item.id)
        .ToDictionary(g => x.Key, g => g.Count() / span.TotalSeconds));

This query will emit a dictionary every 5 seconds that maps each id to its frequency in hertz during the last 30 seconds. Its type is IObservable<Dictionary<string, double>> .