Shuffling while intializing a Observable Collection

Question

Hi,

I want to shuffle a content in ObservableCollection,

 public static ObservableCollection<whatsnewCompleteData> whatsnewCompleteList = new ObservableCollection<whatsnewCompleteData>();

 for (int i = 0; i < whatsnewfeed.feed.entry.Count; i++)
            {              
                    whatsnewCompleteList.Add(new whatsnewCompleteData(i, content[i]);

            }

If it is normal list I can easily perform a shuffle! but observablecollection is directly bound to UI. Only thing I can do is using a random number each time while initializing.

So here for the range of, 

0 < whatsnewfeed.feed.entry.Count

How do I generate a random number and that covers all values from 0 to whatsnewfeed.feed.entry.count?

---

Sivakumar

Answer 1

Hi,

This is how you can generate a random number:

Random random = new Random();
int randomNumber = random.Next(0, whatsnewfeed.feed.entry.Count);

(whatsnewfeed.feed.entry.Count not included)

Answer 2

But I may get repetitions in this way of approach! 

---

Sivakumar

Answer 3

Do something like this:

void ShuffleObservable<T>(ObservableCollection<T> target)
{
     ObservableCollection<T> intermediate = new ObservableCollection<T>();
     foreach(T item in target)
         Intermediate.Add(t);
     Target.Clear();

     Random R = new Random();
     while(intermediate.Count>0)
     {
          int index = R.Next(0, intermediate.Length-1);
          target.Add(intermediate[index]);
          intermediate.RemoveAt(index);
     }     
}

Then, call ShuffleObservable<MyItemType>(list), where MyItemType is the type of object stored in your observable collection.

This will work well with small collections.  If you have millions of items, it will take a long time.

I also haven't compiled it...  Ceck the Random.Next function- you may not have to subtract 1 from intermediate.Length IF .Next returns numbers between the two parameters.

---

Darin R.