Binaryworld - A For Each statement that visits items in random order ... [ VB.net -> Arrays ]

At times you may need to process elements of an array, a collection, or a dictionary object in random order, for example when sampling a population or (more often) when writing a game, such as a card game. Here's a class that you can use in a For Each statement to randomly process all the elements of any data structure that implements the IEnumerable interface:

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Class RandomIterator
  Implements IEnumerable

  ' a low-overhead ArrayList to store references
  Dim items As New ArrayList()

  Sub New(ByVal collection As IEnumerable, ByVal seed As Integer)
    ' load all the items in the ArrayList, but in random order
    Dim rand As New Random(seed)
    Dim o As Object
    For Each o In collection
      Items.Insert(Rand.Next(0, Items.Count + 1), o)
    Next
  End Sub

  Public Function GetEnumerator() As System.Collections.IEnumerator _
    Implements System.Collections.IEnumerable.GetEnumerator
    ' return the enumerator of the inner ArrayList
    Return items.GetEnumerator()
  End Function
End Class

This code shows how you can use the RandomIterator class to randomly process all the elements in a string array, but you can use it with collection and dictionaries alike:

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Dim arr() As String = {"one", "two", "three", "four", "five" }
Dim s As String
' the sequence you obtain depends on the seed you pass as the 2nd argument
For Each s In New RandomIterator(arr, 1234)
Console.WriteLine(s)
Next

This code produces the following sequence:
three
five
two
four
one