Question

I have a class with an integer property. I have a list of them that are to be used in a charting application. I want to display this property as a cumulative total, while retaining all of the other class information.

Let’s call this class ProgressMeasurement and the property is OutstandingItems. Is there some method, using the Aggregate function where I can accomplish this?

For example:

progressMeasurementList.Aggregate((a, b) =>  b.OutstandingItems += a.OutstandingItems));

i.e. I want to update b‘s OutstandingItems value to be the current running total.

Cheers

Answer 1

There’s nothing built in but you can create your own extension method:

public static IEnumerable<TAccum> Scan<T, TAccum>(this IEnumerable<T> seq, TAccum init, Func<TAccum, T, TAccum> op)
{
    TAccum current = init;
    foreach(T item in seq)
    {
        current = op(current, item);
        yield return current;
    }
}

You can then calculate a sequence of cumulative sums as:

var runningTotals = progressMeasurementList.Scan((acc, b) =>  acc + b.OutstandingItems));