Question

How can I modify my method to check only indexes that are equal zero while modulo 17?
I would like to get from that indexes all items that are equal also zero.

My List<byte[]> listOfArrays is storing arrays with values 0,1

This is my method:

public List<int> Funct(List<byte[]> listOfArrays)
        {
            List<int> pixelsList = new List<int>();
            foreach (byte[] t in listOfArrays)
            {
                //count how many items with value 0
                var pixelsInArray = t.Count(n => n == 0);

                var firstElement = Array.FindIndex(t, i => i == 0);
                var lastElement = Array.FindLastIndex(t, i => i == 0);

                pixelsList.Add(pixelsInArray);
            }
            return pixelsList;
        }

In that method I search in all indexes.

I would appreciate your help.
PS. Please check my grammar if need to correct.

Answer 1

this should do the trick if i understand properly:

  public List<int> Funct(List<byte[]> listOfArrays)
  {
     List<int> pixelsList = new List<int>();
     foreach (byte[] t in listOfArrays)
     {
        int counter = 0;
        t.ForEachWithIndex((value, index) =>
                              {
                                 if (value == 0 && index % 17 == 0)
                                 {
                                  // your values
                                  counter++;                                      
                                 }
                              }); 

       pixelsList.Add(counter);
     }

     return pixelsList;
  }

Extension found in:
How do you get the index of the current iteration of a foreach loop?

namespace MyExtensions
{
   public static class ForEachExtensions
   {
      public static void ForEachWithIndex<T>(this IEnumerable<T> enumerable, Action<T, int> handler)
      {
         int idx = 0;
         foreach (T item in enumerable)
            handler(item, idx++);
      }
   }
}