4_A_VBNET

Public Class Form1
    Dim NumOfElements As Integer = 100
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Me.RichTextBox1.Clear()

        Dim ItemList As New List(Of Integer)
        Dim DiscreteDistrDict As New SortedDictionary(Of Integer, Integer)
        Dim Mean As Double = 0

        Me.GenerateDataset(ItemList)
        Me.PrintDataset(ItemList)

        'MEAN
        Mean = Me.CalculateMean(ItemList)
        'Print MEAN Value
        Me.RichTextBox1.AppendText(vbCrLf & "MEAN (OnlineAlgo) = " & Mean.ToString("F") & vbCrLf)

        'DISCRETE DISTRIBUTION
        Me.CalculateDiscreteDistribution(ItemList, DiscreteDistrDict)
        Me.PrintDiscreteDistribution(DiscreteDistrDict)
    End Sub

    Private Sub GenerateDataset(ItemList As List(Of Integer))
        Dim R As New Random
        Dim RandItem As Integer

        For i As Integer = 1 To NumOfElements
            RandItem = R.Next(0, 11)  'Random Integer From 0 to 10
            ItemList.Add(RandItem)
        Next
    End Sub

    Private Sub PrintDataset(ItemList As List(Of Integer))
        Me.RichTextBox1.AppendText("DATASET:" & vbCrLf)
        For i As Integer = 0 To NumOfElements - 1
            Me.RichTextBox1.AppendText(("Item_" & i + 1 & ":").PadRight(12) & ItemList(i) & vbCrLf)
            REM NB:     The first element of a list is pointed by index i=0.
            REM NB2:    The last element of a list is pointed by index i=NumOfElements-1
        Next
    End Sub

    Private Function CalculateMean(ItemList As List(Of Integer)) As Double
        Dim CurrMean As Double = 0
        Dim ItemCount As Integer = 0
        Dim WrapperObj As Object    'Used to obtain multiple return values from function

        For Each s As Integer In ItemList
            WrapperObj = Me.ArithmeticMean_OnlineAlgo(CurrMean, s, ItemCount)
            CurrMean = WrapperObj(0)
            ItemCount = WrapperObj(1)
        Next

        Return CurrMean
    End Function

    Private Function ArithmeticMean_OnlineAlgo(CurrMean As Double, NextItem As Integer, ItemCount As Integer) As Object
        Return {CurrMean + (NextItem - CurrMean) / (ItemCount + 1), ItemCount + 1}
    End Function

    Private Sub CalculateDiscreteDistribution(ItemList As List(Of Integer), DiscreteDistrDict As SortedDictionary(Of Integer, Integer))
        For Each s As Integer In ItemList
            If DiscreteDistrDict.ContainsKey(s) Then
                DiscreteDistrDict(s) += 1
            Else
                DiscreteDistrDict.Add(s, 1)
            End If
        Next
    End Sub

    Private Sub PrintDiscreteDistribution(Dict As SortedDictionary(Of Integer, Integer))
        Me.RichTextBox1.AppendText(vbCrLf & "DISCRETE DISTRIBUTION:" & vbCrLf _
                                   & "VALUE".PadRight(8) & "COUNT".PadRight(8) _
                                   & "FREQ.".PadRight(8) & "PERC.".PadRight(8) & vbCrLf)
        For Each s As KeyValuePair(Of Integer, Integer) In Dict
            Me.RichTextBox1.AppendText(s.Key.ToString.PadRight(8) & s.Value.ToString.PadRight(8) _
                                   & (s.Value / NumOfElements).ToString().PadRight(8) _
                                   & ((s.Value / NumOfElements * 100).ToString & "%").PadRight(8) _
                                   & vbCrLf)
        Next
    End Sub

    Private Sub RichTextBox1_TextChanged(sender As Object, e As EventArgs) Handles RichTextBox1.TextChanged
        Me.RichTextBox1.ScrollToCaret()
    End Sub
End Class