Saving parallell loop results to a list

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How do I save the results of the method called in the parallel loop that returns a double result to a list? Each time the method is run it returns a result. I want to add that specific result to a list.

Stopwatch sw = new Stopwatch();
     sw.Start();
     for (int i = 0; i < 10; i++)
     {
         SumRootN(i,"t");
     }
     sw.Stop();

     Stopwatch sw2 = new Stopwatch();
     sw2.Start();


     //NEED TO SAVE RESULTS TO LIST
     Parallel.For(0, 10, i => SumRootN(i,"t"));


     sw2.Stop();
     double t = sw2.ElapsedTicks;
     Console.WriteLine("Seq " + sw.ElapsedMilliseconds);
     Console.WriteLine("Parallel " + sw2.ElapsedMilliseconds);

C#

public static double SumRootN(int root,string test)
       {

           double result = 0;
           for (int i = 1; i < 1000000; i++)
           {
               result += Math.Exp(Math.Log(i) / root);

           }
           return result;
       }

Posted 5-Dec-12 2:03am

shekarchee

Updated 5-Dec-12 4:27am

v2

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2 solutions

Solution 1

I'm not entirely sure if this is exactly what you need, but Parallel Aggregation[^] might be your solution.

Posted 5-Dec-12 2:57am

fjdiewornncalwe

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Matt T Heffron · Accepted Answer · 2012-12-05T14:00:00

shekarchee is close, but if you need to keep the results in the same sequence as if it was NOT performed in parallel, then the simplest is to use an array instead of the List<double>.

C#

const int count = 10;
double[] results = new double[count];
Parallel.For(0, count, i => { results[i] = SumRootN(i, "t"); });