How To Handle Missing DataPoints with MSChart (177685)

MORE INFORMATION

The SetData method has four arguments:

• Row - an integer that identifies the row containing the data point value.
• Column - an integer that identifies the column containing the data point value.
• DataPoint - a double that is the data point value.
• NullFlag - an integer flag that indicates if the data point value is a null value.

The last argument determines if the data point is displayed on the chart. If the NullFlag is true, the data point is a null value and the data point is omitted from the chart. If the NullFlag is set to False or is omitted, the data point is displayed as a zero value.

The next section illustrates how you can create a sample project that uses MS Chart to plot missing data points.

Steps to Create Sample Project

1. Start a new Standard EXE project in Visual Basic. Form1 is created by default.
2. Add a CommandButton, Check box, and an MS Chart Control to Form1.
3. Copy the following code to the Code window of Form1:

           Option Explicit
           Option Base 1
           Dim vArray(2, 6) As Variant
   
           Private Sub Form_Load()
              Dim i, j
              For i = 1 To 2
               For j = 1 To 6
                   vArray(i, j) = Int((Rnd(10) + Rnd(10) * 10) * 10)
               Next j
              Next i
   
             Command1.Caption = "SetData Method"
             Check1.Caption = "Null Data Point"
             Check1.Value = vbChecked
           End Sub
   
           Private Sub Command1_Click()
               Dim intCount As Integer, dataflag As Boolean
               Dim column As Integer, row As Integer, anumber As Variant
   
               If Check1.Value = vbChecked Then
                   vArray(1, 4) = vbNull
               Else
                   vArray(1, 4) = 0
               End If
   
               With MSChart1
                .chartType = VtChChartType2dLine
                .ColumnCount = 2
                .RowCount = 6
   
                  For column = 1 To .ColumnCount
                     For row = 1 To .RowCount
                     If (vArray(column, row)) <> vbNull Then
                        dataflag = False
                     Else
                        dataflag = True
                     End If
                     .DataGrid.SetData row, column, _
                                       vArray(column, row), _
                                       dataflag
                     Next row
                  Next column
   
                  With .DataGrid
                   .ColumnLabelCount = 1
                   .ColumnLabel(1, 1) = "abc"
                   .ColumnLabel(2, 1) = "xyz"
                   .RowLabelCount = 1
                   .RowLabel(1, 1) = "Jan"
                   .RowLabel(2, 1) = "Feb"
                   .RowLabel(3, 1) = "Mar"
                   .RowLabel(4, 1) = "Apr"
                   .RowLabel(5, 1) = "May"
                   .RowLabel(6, 1) = "Jun"
                  End With
   
                .ShowLegend = True
               End With
           End Sub
   
   						

4. Click Start on the Run menu, or press the F5 key to start the program. Click SetData Method to display a chart with a missing data point. Uncheck the Null Data Point check box and click SetData Method to display the chart without a Null data point (the data point is zero).

(c) Microsoft Corporation 1997. All Rights Reserved. Contributions by Arsenio Locsin, Microsoft Corporation