Imports System.Windows.Forms.DataVisualization.Charting
 
Public Class frmMonthChart
 
    Dim dt As New DataTable
    Dim cht As New Chart With _
        {.Parent = Me, .Size = New Size(500, 500)}
 
 
    Private Sub frmMonthChart_Load(sender As System.Object, _
                                e As System.EventArgs) Handles MyBase.Load
 
        Me.Size = New Size(520, 560)
 
        'Demo-Datensätze erzeugen
        With dt.Columns
            .Add("Date", GetType(Date))
            .Add("done", GetType(Boolean))
        End With
 
        Dim dx As Date, erl As Boolean
        Dim rndm As New Random(4321)
 
        For i As Integer = 1 To 1000
            With rndm
                dx = _
                New Date(.Next(2015, 2018), .Next(1, 13), .Next(1, 29))
            End With
            erl = (i Mod 2 = 0)
            dt.Rows.Add({dx, erl})
        Next i
 
        'Häufigkeitstabelle aus Demo-Datensätzen erstellen
        Dim dc As New DataTable
        With dc.Columns
            .Add("Month", GetType(String))
            .Add("Freq. done", GetType(Integer))
            .Add("Freq. todo", GetType(Integer))
        End With
 
        dc.PrimaryKey = {dc.Columns("Month")}
 
        For i As Integer = 0 To dt.Rows.Count - 1
            Dim dr As DataRow = dt.Rows(i)
 
            'sortierbarer Jahr-Monat-String
            Dim ym As String = _
             dr.Field(Of Date)("Date").Year.ToString & "-" & _
             dr.Field(Of Date)("Date").Month.ToString("00")
 
            Dim el As Boolean = dr.Field(Of Boolean)("done")
 
            'Datensatzsuche nach Monat in Häufigkeitstabelle
            'gemäß Primärschlüssel     
            Dim dcr As DataRow = dc.Rows.Find({ym})
            If dcr Is Nothing Then
                dcr = dc.Rows.Add({ym, 0, 0})
            End If
 
            Dim fcol As String
            If el Then
                fcol = dc.Columns(1).ColumnName
            Else
                fcol = dc.Columns(2).ColumnName
            End If
 
            'Häufigkeit bestimmen
            dcr(fcol) = CInt(dcr(fcol)) + 1
        Next i
 
        Dim bs As New BindingSource With {.DataSource = dc}
        bs.Sort = "Month ASC"
 
        'Chart für Häufigkeiten erstellen
        With cht
            .DataSource = bs
            .ChartAreas.Add("Base")
            With .ChartAreas("Base").AxisX
                .LabelStyle.Angle = 45
                .MajorTickMark.Interval = 1
                .LabelStyle.Interval = 3
            End With
 
            .Series.Add("Month-done")
            With .Series("Month-done")
                .XValueMember = "Month"
                .YValueMembers = dc.Columns(1).ColumnName
                .ChartType = SeriesChartType.StackedColumn
                .ChartArea = "Base"
            End With
 
            .Series.Add("Month-todo")
            With .Series("Month-todo")
                .XValueMember = "Month"
                .ChartType = SeriesChartType.StackedColumn
                .YValueMembers = dc.Columns(2).ColumnName
                .ChartArea = "Base"
            End With
        End With
    End Sub
End Class