Q177685: HOWTO: Handle Missing DataPoints with MSChart

Article: Q177685
Product(s): Microsoft Visual Basic for Windows
Version(s): 
Operating System(s): 
Keyword(s): kbGrpDSVB
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 
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SUMMARY
=======

The last argument of the SetData method determines if the data point is a null
value. When this flag is True, the data point is null and the value is omitted
from the chart. It is often desirable that a data point is omitted rather than
treated as zero. This article illustrates how to use the MS Chart control to
create data points that are omitted, or missing, from the plot.

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


Additional query words: kbVBp500 kbVBp600 kbVBp kbdsd kbDSupport kbControl

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Keywords          : kbGrpDSVB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600
Issue type        : kbhowto

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